Infections - Soft Tissue - Hand Flashcards

Question

A 25-year-old man is brought to the emergency department four hours after being bitten by a raccoon. He has not been previously vaccinated for rabies. In addition to irrigation of the wound, which of the following is the most appropriate management?

Answer 1

The correct response is Option D. In a patient who has been bitten by a potentially rabid animal and who has not been previously vaccinated, management should include wound care and administration of both rabies immune globulin (RIG) and rabies vaccine. Because rabies incubation periods of more than one year have been reported in humans, the prophylactic regimen should be initiated immediately in any person who has been bitten by an animal with suspected or proven rabies regardless of the length of the delay, as long as clinical signs of rabies are not present. Studies have shown that a regimen of one dose of RIG and five doses of human diploid cell vaccine (HDCV) over a 28-day period is a safe treatment protocol that induces an excellent antibody response. Immediate, thorough washing of all bite wounds and scratches with soap and water and irrigation with a virucidal agent (such as a povidone-iodine solution) are also important for preventing rabies. Experimental animal studies have shown that thorough wound cleansing alone without other postexposure prophylaxis markedly decreased the likelihood of rabies. In addition, tetanus prophylaxis and measures to control bacterial infection should be administered as indicated. Suturing of large wounds should be based on cosmetic factors and the potential for bacterial infection. Prophylactic administration of both passive antibody and vaccine is indicated in all exposed patients except for those who have previously received complete vaccination regimens (preexposure or postexposure) with a cell culture vaccine or those persons who have been vaccinated with other types of vaccines and have had documented rabies antibody titers. Instead, these persons should receive the vaccine only. This combination of RIG and vaccine is also recommended for patients who have been exposed to rabies without specifically being bitten.

Answer 2

The correct response is Option C. In this clinical scenario of a snakebite to the upper extremity, the patient meets criteria for moderate envenomation, which can also yield orthostatic changes and mild coagulation parameter changes. Guidelines for management include the administration of 10 to 20 vials of antivenin after skin testing with horse serum for possible hypersensitivity reaction. Criteria for minimal envenomation include fang marks, local swelling or pain, and no systemic reaction; therapy includes delivery of up to five vials of antivenin. Severe envenomation can produce subcutaneous ecchymosis, marked swelling of the extremity, coagulopathy, shock, and compartment syndrome; therapy includes delivery of 20 or more vials of antivenin (without delaying for skin testing), resuscitation with correction of acidosis and coagulopathy, and fasciotomy for compartment pressures greater than 30 mmHg or worsening findings on neurologic examination. Tourniquets and cryotherapy, although used in the past, are controversial and may be associated with increased tissue damage. Resuscitation should be performed with lactated Ringer’s solution. Normal saline is contraindicated because this solution will exacerbate metabolic acidosis due to its high chloride load (154 mEq/l). In a series of 107 patients with pit viper snakebites managed at a university teaching hospital in the southeastern U.S., 27% of patients underwent surgical debridement and 4% of patients required fasciotomies. Antivenin was administered to 34 patients, and serum sickness developed in nine patients. Coagulopathy was present in 4% of patients, and no deaths were reported. Copperhead bites accounted for 68% of all envenomations.

Answer 3

The correct response is Option D. Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are in the spectrum of the same disease process, characterized by a severe drug-induced immune reaction. The drug or its metabolite acts as a hapten and provides antigenic stimulation for a T-cell–mediated delayed hypersensitivity reaction. The list of offending medications is extensive and includes antibiotics, anticonvulsants and NSAIDs. Onset is within the first 8 weeks of starting the medication, and is characterized by fever, mucositis and a painful generalized vesiculobullous rash. Histology of skin specimens reveals keratinocyte apoptosis, full-thickness necrosis of the epidermis, and minimal dermal inflammation. Mucosal inflammation can involve any mucosal surface. Cutaneous involvement consists of blisters and erosions, with skin separation. Application of shear forces on the skin results in separation of the epidermis (Nikolsky sign). Skin separation of less than 10% of total body surface area is classified as SJS, greater than 30% of total body surface area as TEN, and 10 to 30% of total body surface area as SJS-TEN overlap. Multisystem organ dysfunction can occur. Treatment is supportive, with the best outcomes in patients treated early in a burn center. Intravenous corticosteroids are usually given, although their use is controversial. Mortality is 1 to 5% in SJS and 25 to 40% in TEN. Survivors are often left with skin scarring, mucosal strictures, and ocular complications. Toxic shock syndrome (TSS) is caused by toxin-producing strains of Staphylococcus aureus and Streptococcus pyogenes. The toxin acts as a super antigen and causes widespread immune stimulation. Staphylococcal Toxic Shock Syndrome can occur after surgical or traumatic skin break or from colonization of a foreign body. Onset is within 48 hours of surgery and consists of influenza-like symptoms, fevers, and shock. Multisystem organ failure can occur. Skin desquamation usually occurs 2 to 3 weeks later. Treatment consists of source control, antibiotic therapy, and in some cases, immunoglobulins. Acute generalized exanthematous pustulosis (AGEP) is a T-cell–mediated cutaneous drug reaction. Onset is usually within 48 hours and consists of fever, leukocytosis, and a rash consisting of many small sterile non-follicular pustules distributed predominantly on the trunk and intertriginous areas. Mucous membrane involvement is uncommon and occurs mostly in the lips and buccal mucosa. Internal organ involvement occurs in a minority of cases but can lead to multisystem organ dysfunction. Histology shows intracorneal, sub-corneal, and intraepidermal pustules and a dermal neutrophilic and eosinophilic infiltrate. Treatment is discontinuation of the offending drug, after which the condition quickly resolves. Prognosis is excellent. Drug reaction with eosinophilia and systemic symptoms (DRESS) is a severe drug reaction of unclear pathogenesis that is characterized by fever, hematological abnormalities (leukocytosis, eosinophilia), and internal organ dysfunction. Onset is typically 2 to 8 weeks after drug exposure. Antiepileptics are most commonly implicated, although a variety of drugs, including antibiotics, can be the causative agent. Cutaneous involvement consists of a morbilliform rash. Mucosal involvement is frequent. Facial edema can be severe. Blood leukocytes are markedly elevated, with 30% of cases having eosinophilia. Multisystem organ dysfunction can occur. Histopathology reveals a perivascular lymphocytic infiltrate in the papillary dermis and dermal edema with extravasated erythrocytes and eosinophils. Treatment consists of cessation of the offending drug, systemic glucocorticoids and supportive care.

Answer 4

The correct response is Option E. This patient has developed infection with Aeromonas hydrophila after undergoing leech therapy for five days. Medicinal leeches such as the Hirudo medicinalis species (which is the most commonly used leech and is endemic to Southeast Asia and Europe) can be applied to flaps or replanted limbs in order to relieve venous congestion. However, a common complication of leech therapy is the development of infectious organisms such as Aeromonas hydrophila, a gram-negative rod that can be detected in as many as 20% of persons within the first 10 days of therapy. Infiltration of Aeromonas hydrophila organisms can result in a rapidly progressive infection with gas in the soft tissues that can resemble clostridial myonecrosis. If infection does develop, trimethoprim-sulfamethoxazole is recommended for first-line therapy. Fluoroquinolones such as ciprofloxacin are also effective. Antibiotics that are still effective but less frequently recommended include antipseudomonal aminoglycoside, imipenem, meropenem, tetracycline, and second-, third-, or fourth-generation cephalosporins.

Answer 5

The correct answer is option a. This patient has developed an infection caused by a member of the poxvirus family that is endemic in sheep and goats. In humans the infection is known as human orf infection. An identical infection may occur from contact with infected cattle in which case it is known as milkers’ nodule. In either case the disease is self limiting and typically resolves within six weeks in immunocompetent hosts. Failure to recognize the correct diagnosis may lead to unnecessary surgical interventions including amputation.

Answer 6

The correct response is Option D. Infections of the head and neck should not be ignored, as many of them can evolve into life-threatening emergencies, some of them very quickly. Rhinocerebral mucormycosis is a rare opportunistic infection of the nasal cavity and sinuses that can rapidly spread to the orbits and brain by erosion of bone and invasion of blood vessels. Mucormycosis is caused by saprophytic fungi, and usually affects individuals with diabetes mellitus and those who are immunocompromised. The mainstay of treatment includes reversal of immunosuppression when possible, systemic antifungals, and surgical debridement. Timely treatment is critical and usually dependent on rapid diagnosis by history and physical examination, imaging, and intraoperative biopsy with frozen section pathology, since waiting for cultures causes unnecessary delay in severe cases. Mucormycosis can also present in the oral cavity, lungs, ears, and other sites less commonly. Epiglottitis is an infection of the supraglottic region causing inflammation and swelling of the epiglottis. It is most commonly caused by Haemophilus influenzae type b and has become rare since the introduction of the vaccine against this bacteria. Swelling of the epiglottis can cause airway obstruction. Mastoiditis is infection of the mastoid air cells, which are in continuity with the middle ear. The mastoid process behind the ear is also usually swollen and tender. Infections usually start from untreated otitis media. Risks include spreading to the surrounding structures, including the brain. Necrotizing fasciitis is a soft tissue infection that rapidly spreads through the subcutaneous fat and fascia with necrosis of the overlying skin. In the head and neck, the infection is usually spread from infection of the teeth or pharynx. The plaque-like infection of candidiaisis does not present in this fashion.

Answer 7

The correct response is Option D. The history and presentation are classic for an atypical mycobacterial infection. Unlike bacterial infections, atypical mycobacteria rarely produce systemic signs of infection and often manifest as a nonhealing (sometimes progressive) wound. Given the history of injury on a boat dock, the most likely causative organism is Mycobacterium marinum, an acid-fast bacillus that lives in water environments. This pathogen results in localized granulomas such as the one seen in this patient. Staphylococcus aureus is the most common source of skin infections but typically results in a more pronounced and acute immune reaction with localized redness and purulence. These findings are not present in this patient. Cutaneous infections with Group A beta-hemolytic Streptococcus and Vibrio vulnificus tend to increase rapidly and are often accompanied by severe systemic response (i.e., necrotizing fasciitis). Candida tropicalis is a fungus that is often part of normal skin flora. It is related to Candida albicans and can produce opportunistic internal infections in susceptible individuals.

Answer 8

**The correct answer is option E.** **Rationale:** The 2023 Evidence-Based Consensus Conference Statement provides specific, procedure-driven recommendations. For tissue expander breast reconstruction, antibiotic prophylaxis is recommended. For patients with a penicillin allergy, clindamycin is the appropriate alternative agent. The guideline specifies a total prophylactic duration of one day, which includes a preoperative dose and postoperative continuation for up to 24 hours (e.g., clindamycin 600 mg IV every 8 hours postoperatively). This one-day regimen is supported by level I evidence. Option E correctly specifies the correct agent, preoperative dose, and the evidence-based one-day postoperative duration. Option B is incorrect because it describes a single preoperative dose only, which does not fulfill the recommended duration. Options C and D recommend prolonged durations (until drain removal or for 48 hours), which are not supported by evidence and are associated with increased risks of adverse effects and antimicrobial resistance without reducing surgical site infection rates. Option A is incorrect, as prophylaxis is recommended for prosthetic-based breast reconstruction. **References:** 1. Klifto KM, Rydz AC, Biswas S, Hultman CS, Erdmann D, Phillips BT. Evidence-based medicine: systemic perioperative antibiotic prophylaxis for prevention of surgical-site infections in plastic and reconstructive surgery. *Plast Reconstr Surg.* 2023;152(6):1154e-1182e. (See Tables 2, 3, and associated clinical recommendations for Breast Reconstruction: Tissue Expansion).

Answer 9

The correct response is Option C. For the patient described with a penicillin or cephalosporin allergy, trimethoprim-sulfamethoxazole (TMP/SMX) and clindamycin or metronidazole, or a fluoroquinolone and clindamycin or metronidazole, are good antibiotic therapy combinations. Cat bites account for 5 to 15% of animal bites and occur more often in women and adults (median age is 20 years). Most cat bite injuries occur on the upper extremity with 'scratches' on the finger or hand. Infection rates after cat bites range from 50 to 75%. This is typically attributed to the fine, sharp teeth of cats, which produce puncture wounds and penetrate deeply into the soft tissues and joint capsules of the hand. Wounds to the hand demonstrate an increased risk of infection; closed fist injuries have the highest risk. Initial medical management of bite wounds includes ascertaining the rabies status of the animal and updating the tetanus immunization of the patient if necessary. If rabies is suspected, irrigation with povidone-iodine solution will reduce the development by up to 90%. A careful examination of the affected hand/extremity should address the surrounding soft tissues and potential spaces of the hand, tendons, joint and joint capsules, and underlying bone. The wound should be irrigated with saline after obtaining wound cultures. Necrotic tissue should be debrided, and any cat bite with worsening pain will require incision and irrigation of the puncture site. All cat bite wounds should be left open, although large gaping wounds can be loosely approximated. Before definitive surgical treatment of any associated abscess or debridement of devitalized tissue, empiric antibiotic therapy should be started. The majority of cat bite wounds are polymicrobial and the anaerobic organisms are often overlooked. Common aerobic pathogens include Staphylococcus aureus, viridans streptococcus, Corynebacterium, Pasteurella multocida, and various gram-negative enteric organisms. The most common anaerobic pathogens include Bacteroides, Fusobacterium, Peptostreptococcus, and Actinomyces species. Pasteurella multocida, an aerobic, facultative anaerobic gram-negative pathogen, is the most commonly isolated pathogen in cat bites and is present in up to 50% of infected wounds. Symptoms of Pasteurella multocida infection develop rapidly within 24 hours and typically include cellulitis and seropurulent drainage. Other uncommon infections have been reported after cat bites, including tularemia (Francisella tularensis) and cat-scratch disease (Bartonella henselae). Patients with severe wounds (crush injury, joint involvement, deep space infection), cellulitis, sepsis, diabetes, immunosuppression, or other high-risk factors for treatment failure should receive parenteral antibiotics. Alternatives to amoxicillin and clavulanate potassium or ampicillin and sulbactam include other penicillins or cephalosporins, provided they display adequate anaerobic coverage. In the scenario described, the choices containing amoxicillin, ampicillin, and cefazolin are not appropriate because of the patient’s penicillin allergy. Additionally, this patient will require intravenous antibiotics because of the wound severity, so amoxicillin and clavulanate potassium would not be appropriate. The combination of tetracycline and TMP/SMX alone does not provide adequate anaerobic coverage.

Answer 10

The correct response is Option B. Oral metronidazole is the most appropriate treatment for this patient with a mild/moderate form of Clostridium difficile infection. Oral vancomycin is recommended for treatment of those with severe disease, or with mild/moderate disease who did not respond to metronidazole. Patients who cannot tolerate oral medications (eg, postoperative ileus) or who have an intestinal diversion (eg, ileostomy) can be treated with intravenous metronidazole or with vancomycin enemas. Vancomycin is not excreted into the colon and therefore should not be given intravenously to treat C. difficile infection. Oral fidaxomicin has been shown to be as effective as oral vancomycin in the treatment of C. difficile infections. Although further clinical experience is still needed, this drug has been associated with increased cure rate in patients receiving concomitant antibiotics and decreased infection recurrence when compared to vancomycin. Teicoplanin and rifaximin are not generally recommended for treatment of C. difficile, although isolated reports of successful therapy can be found in the literature.

Answer 11

The correct answer is option C. Herpetic whitlow is most commonly caused by herpes simplex virus type 1. Herpetic whitlow can be extremely painful. In contradistinction to a true felon, the pulp space with HSV infection remains soft. Frequently the diagnosis is made on clinical rounds, but confirmation can be obtained with a Tzanck smear (lesion scraping and staining with toluidine blue, which reveals multinucleated giant cells with ground glass chromatin appearance, which is specific for HSV). Incision and drainage is contraindicated as the process usually is self-limited and surgical treatment may cause a secondary bacterial infection. The most infectious time period of the disease process is the late phase (beginning with 12–14 days for pain, blistering and ulceration formation, followed by 7–10 days for symptoms to subside, followed by approximately 12 days of viral shedding).

Answer 12

The correct response is Option A. This patient has compartment syndrome due to a snake bite. Pain is the hallmark of compartment syndrome and is accentuated by passive stretching of the involved muscle compartment, which is the most consistent early sign. Patients with injuries of the upper and lower extremities should be closely monitored for the presence of muscle, nerve, and tissue ischemia. However, compartment syndrome occurring in conjunction with a pit viper or other snake bite is often worse than other types of compartment syndrome. Because the venom is injected directly into the tissues, tissue destruction occurs rapidly, leading to the immediate onset of edema, ecchymosis, and swelling. Measurement of compartment pressures is an important step in the diagnosis of compartment syndrome, especially in patients who have sustained head trauma or spinal cord injuries. Decompressive fasciotomy should be performed in normotensive patients when compartment pressures are greater than 30 mmHg and the duration of symptoms is longer than eight hours or is unknown or the patient is unconscious or uncooperative. Patients with hypotension and compartment pressures greater than 20 mmHg should also undergo surgery within six hours. In some patients with compartment syndrome, central or peripheral sensory deficits or late nerve ischemia may preclude the presence of pain as a diagnostic finding. In compartment syndrome, distal pulses may still be present. The affected extremity may appear cyanotic, pale, or normal. Sensation may be normal or diminished. Tenseness and tenderness of the closed compartments are nonspecific findings that are not necessarily associated with ischemic tissue damage.

Answer 13

The correct response is Option B. Vibrio vulnificus is a common Vibrio species causing soft-tissue infections of the hand. Vibrio species are ubiquitous in aquatic environments including saltwater bodies. Immunocompromised hosts are at greater risk for amputation and death. The best chance for patient survival includes early diagnosis and initiation of appropriate antibiotics, as well as urgent surgical debridement for any evidence of necrotizing infection. A broad range of antibiotics are effective against Vibrio species, including V. vulnificus. Agents effective against gram-negative rods, including quinolones, aminoglycosides, and aminopenicillins, are all effective against V. vulnificus. While all cephalosporins are effective against Vibrio species, third-generation cephalosporins are up to 130 times more potent than first- or second-generation cephalosporins. Vancomycin, nafcillin, and linezolid are all narrow-spectrum antibiotics, primarily effective against gram-positive cocci, and are not effective against Vibrio species.

Answer 14

The correct response is Option D. The brown recluse spider (Loxosceles reclusa) is one of two species of North American spider capable of envenomation. It is generally found throughout the southern United States. This spider is believed to be nocturnal but may also be active during the day; it does not weave a web. Features include long slender legs and a distinctive fiddle-shaped marking on its dorsal cephalothorax. Both male and female brown recluse spiders are venomous. Most patients are unaware that they have been bitten by this spider until pain develops or the wound becomes noticeable. Blistering, ischemia, and ulceration may be seen and can ultimately lead to necrosis. Conservative treatment with administration of dapsone 100 mg daily for 14 days is advocated as the injury is often more extensive than initially thought. There is no antivenin to brown recluse spider venom. Dapsone is a leukocyte inhibitor that has both bacteriostatic and bacteriocidal properties and is frequently used in the treatment of leprosy. Hemolysis is the most common adverse effect of dapsone therapy. Because of the risk for hemolysis and other hematologic side effects, including methemoglobinemia, blood counts should be measured weekly. In addition, dapsone should not be administered to patients who have glucose-6 phosphate dehydrogenase deficiency. Diarrhea, diplopia, headache, and peripheral neuropathy are not complications of dapsone therapy.

Answer 15

The correct response is Option D. This patient's findings are most consistent with toxic shock syndrome. This condition should be suspected in any patient who has fever, hypotension, and erythroderma following surgery, trauma, or infection of structures related to the skin or nares. Symptoms include a temperature greater than 38.9%C (102%F), a diffuse macular rash, and a systolic blood pressure of less than 90 mmHg in adults or less than the fifth percentile for children younger than 16 years. Syncope and orthostatic hypotension are also common. Desquamation of the palms and soles typically occurs one to two weeks after the onset of illness. Appropriate management should include supportive treatment for multisystem organ involvement, antibiotics effective against Staphylococcus aureus, and identification and treatment of the focus of bacterial toxin production. Although the Staphylococcus organisms that produce toxic shock syndrome toxin typically do not produce purulent wounds and the surgical wound may appear normal, an undrained focus of infection may be present in the wound. Therefore, the wound should be debrided to locate any potential source of toxin-producing organisms and to provide tissue for bacterial culture. Acute gastroenteritis is associated with the abrupt onset of hypotension and abdominal symptoms such as nausea and diarrhea. Erythroderma is not an associated finding. Kawasaki disease is a multisystem disease typically seen in children younger than 7 years and characterized by prolonged fever, lymphadenitis, conjunctivitis, and erythema of the mucous membranes. Thrombocytosis and desquamation of the distal digits occur during the recovery phase. Hypotension is rare. Infection with Staphylococcus aureus and/or Streptococcus pyogenes is not associated. Patients with Stevens-Johnson syndrome have a systemic, widespread rash that also affects the mucous membranes. This condition can result from infection, illness, or an allergic reaction to medication. Systemic symptoms are typically severe. In patients with urosepsis, the onset of septic shock can be typically distinguished from toxic shock syndrome by the absence of erythroderma. Profuse watery diarrhea is uncommon in patients with urosepsis but occurs frequently in patients with toxic shock syndrome.

Answer 16

The correct response is Option A. Cat and dog bite infections have a complex microbiologic mix, with Pasteurella as the most frequent isolate. Common aerobes isolated include streptococci, staphylococci, Moraxella, and Neisseria; common anaerobes include Fusobacterium, Bacteroides, Porphyromonas, and Prevotella. Patients are most often treated with a combination of a β-lactam antibiotic and a β-lactamase inhibitor, such as amoxicillin and clavulanic acid. Alternative treatments include clindamycin plus fluoroquinolone for adults and clindamycin and trimethoprim/sulfamethoxazole for children. Ciprofloxacin does not provide adequate coverage for expected pathogens. In general, cat bites tend to be small puncture wounds that seal almost immediately; thus, wounds should be opened sufficiently to be cleaned and allowed to drain. Dog bite wounds tend to be longitudinal lacerations that are more likely to stay open by themselves. However, canine lacerations, as compared to cat bite punctures, are more likely to result in direct structural damage to nerves, tendons, vessels, and joint structures. Rabies is uncommon in dogs and cats in the United States. Because the cat owner is known, the vaccination record is obtainable. An animal that appears healthy and has been vaccinated should still be quarantined for 10 days to ensure it does not show signs of rabies. If the animal is found to have rabies, postexposure prophylaxis should be started as soon as possible. If the animal is a stray, the animal should be located so it can be tested for rabies. If, however, the animal cannot be located, postexposure prophylaxis is reasonable. Administration of tetanus immune globulin is recommended only for patients with tetanus-prone wounds who have never completed a primary immunization series. If a patient with an acute soft-tissue injury has not been immunized previously, a tetanus toxoid booster is required. The patient must complete the series. If the patient has been immunized previously, a booster dose is given if the last dose was more than five years previously (for a tetanus-prone wound) or more than 10 years previously (for a nontetanus-prone wound). Patients with a contraindication to tetanus toxoid must be managed with tetanus immune globulin alone. Observation alone would not be appropriate for a deep puncture wound with purulent drainage and a mildly elevated leukocyte count. After adequate drainage of the wound and treatment with oral antibiotics, the patient requires follow-up to ensure the infection does not progress, possibly requiring intravenous antibiotics and further surgical drainage.

Answer 17

The correct response is Option E. **Necrotizing fasciitis** is a rapidly progressive soft-tissue infection characterized by necrosis of the fascia and subcutaneous fat with subsequent necrosis of the overlying skin. Although complication rates associated with liposuction are not unduly increased, infection is a major concern, and cases of prolonged inflammation, septic shock, and infections have been documented. Likewise, cases of necrotizing fasciitis following liposuction have been reported on several occasions and, according to data reported in the literature, the overall incidence of necrotizing fasciitis is equal to 0.4 per 100,000 patients. There are two common forms that are reported: infections caused by Streptococcus pyogenes and mixed infections caused by a variety of microbes, including Escherichia coli, Proteus, Serratia, and Staphylococcus aureus. A detailed case of necrotizing fasciitis sustained by Mycobacterium chelonae after a combined procedure of liposuction and lipofilling has also been described. The progressive necrosis of the tissues typically involves the superficial fascia and the subcutaneous layer, but is limited in extension to the skin; the extent of the gangrene at the fascial layer is usually more severe and greater than at the skin level. Necrotizing fasciitis is virtually unnoticeable in the first 48 hours with nonspecific symptoms. In the days that follow, an extensive, hardened region forms, which is often dark in the center. Severe pain and necrosis follow at the level of the infection. Drainage of “dishwater fluid” is often pathognomonic. Metabolic changes occur, ending with respiratory distress, oliguria, acidosis, increased troponin concentrations, and sepsis. Diagnosis and treatment consist of surgical exploration and debridement that reveal necrotic, edematous, subcutaneous fat. Bacteriologic analysis of exudate, cultures, and histologic evaluation complete the diagnosis. Early diagnosis is imperative to avoid a fatal outcome. Treatment is based on immediate and aggressive surgical debridement with combined antibiotic therapy. Because necrotizing fasciitis is a progressive, rapid infection, the wound typically is left open for a planned “second-look” operation and additional debridement if necessary. The mortality rates are increased and range up to 70% but decrease to 4.2% after immediate surgical intervention. Delay in debridement increases mortality. Necrotizing fasciitis is differentiated into types primarily by microbiology and clinical context. The two main types are: **Type I (polymicrobial):** Caused by a mix of aerobic and anaerobic bacteria, often seen in older adults or those with comorbidities (e.g., diabetes, immunosuppression). It frequently follows breaches in the gastrointestinal or genitourinary tract (e.g., perineal infections, Fournier’s gangrene) and is more likely to present with gas in tissues. Clinical features may include insidious onset and association with chronic wounds or surgical sites. **Type II (monomicrobial):** Most commonly due to group A Streptococcus (GAS), but can also be caused by Staphylococcus aureus (including MRSA), Aeromonas hydrophila, or Vibrio vulnificus. This type can affect healthy individuals of any age, often after minor trauma, and typically presents with rapid progression, severe pain out of proportion to exam, and systemic toxicity. - Some experts propose a **Type III** for infections caused by specific organisms such as Vibrio or Aeromonas, but this classification is not universally adopted.[1][2] The Infectious Diseases Society of America emphasizes that, while microbiologic differentiation is important for epidemiology and targeted therapy, the initial management (surgical debridement and broad-spectrum antibiotics) is similar for all types and should not be delayed for definitive classification.[2] 1. Necrotizing Soft-Tissue Infections. Stevens DL, Bryant AE. The New England Journal of Medicine. 2017;377(23):2253-2265. doi:10.1056/NEJMra1600673. 2. Practice Guidelines for the Diagnosis and Management of Skin and Soft Tissue Infections: 2014 Update by the Infectious Diseases Society of America. Stevens DL, Bisno AL, Chambers HF, et al. Clinical Infectious Diseases : An Official Publication of the Infectious Diseases Society of America. 2014;59(2):147-59. doi:10.1093/cid/ciu296.

Answer 18

The correct response is Option D. Necrotizing fasciitis is a severe soft-tissue infection affecting the skin, subcutaneous tissue, and fascia. It characteristically spares the underlying muscle, progresses quickly, and is associated with high morbidity and mortality rates and severe systemic sepsis. The inciting event is often trauma, even minor trauma and small puncture wounds, but hematogenous spread is also a recognized etiology. The vast majority of patients have some form of chronic debilitating disease that weakens the immune system. Diabetes mellitus appears to be the most common disease, but these may include substance abuse and renal failure. These patients are at higher risk for increased mortality. Two types of necrotizing fasciitis have been described. Type I are mixed aerobic and anaerobic infections, with facultative anaerobic bacteria and non-group A streptococci being present. This is the most common type and is present in about 75% of cases. Type II infections are monomicrobic and are caused by group A Streptococcus species alone or in combination with staphylococcal species. For this reason, antibiotic coverage should be broad. The disease progresses quickly but does evolve through several stages. Initial symptoms include tenderness, erythema, edema, warm skin, and fever; however, symptoms may vary depending on patient characteristics. Initial lab findings may include leukocytosis, thrombocytopenia, and hyperkalemia, but these are variable. When critical skin ischemia occurs, blisters or bullae are formed. In the late stage, lesions turn black and necrotic and are anesthetic as the nerves become involved. Diagnosis begins with a high clinical suspicion in all patients, particularly those with risk factors. Appropriate treatment is surgical debridement, broad-spectrum intravenous antibiotic therapy covering gram-positive, gram-negative, and anaerobic organisms, and careful monitoring and correction of fluid and electrolytes in an intensive care setting. Most authorities agree that hyperbaric oxygen is to be recommended for the treatment of necrotizing fasciitis as an adjunct, if facilities are available and there is no delay in surgical debridement. However, most studies regarding the efficacy of hyperbaric oxygen are anecdotal with a distinct lack of properly designed prospective randomized controlled trials. Mortality rates are reported to be 10 to 75% and are increased in patients with underlying immune compromise, delayed treatment, or involvement of the chest wall.

Answer 19

The correct response is Option D. The patient described has cervical necrotizing fasciitis (CNF) that likely extends into the mediastinum. Pharyngeal and tonsillar infections, along with dental abscesses, are the most common sources of infection. Diabetes and other immunocompromised states are frequent comorbidities in this disease. Early presentation may be clinically indistinguishable from a superficial soft-tissue infection and, therefore, requires a high index of suspicion. Skin necrosis is often a late finding, as the infection begins in the fascial and deep tissues of the neck. CT scan is usually obtained to define the extent of the disease and may or may not show gas within the soft tissues. Patients are treated with broad-spectrum antibiotics and aggressive surgical debridement. Mastoiditis is an infection of the mastoid air cells usually arising in the setting of untreated otitis media. Mastoiditis can spread to surrounding structures, including the brain. Meningitis is an infection of the meninges that is associated with neck pain as well as fever, headache, and photophobia. It does not present with unilateral neck erythema and swelling. Parotitis is an infection of the parotid gland that usually arises in the setting of an obstructed parotid duct and is a very rare but potential cause of CNF. Sinusitis is not usually associated with CNF but may spread to the orbit, resulting in orbital cellulitis or orbital abscess, and, occasionally, cavernous sinus thrombosis. Cavernous sinus thrombosis is a life-threatening condition.

Answer 20

The correct response is Option B. Bacterial resistance to host defense peptides is an unfortunate reality that is clinically and experimentally observed. The significant diversity of host defense peptide mechanisms requires the resistance strategies to use equally numerous solutions based on the specific peptide or target organism. Common resistance mechanisms used by bacteria against host defense peptides include: 1) decreased carotenoid content in cell membranes (not increased) 2) increased protease expression (not inhibition) 3) biofilm production (not reduction) 4) increased expression of binding ligands to host defense peptides (not suppression) Esterification of cell membrane lipoteichoic acid with D-alanine is a commonly used mechanism of gram-positive bacterial antimicrobial resistance. REFERENCES: 1. DeLong MR, Tandon VJ, Da Lio AL, Deming TJ, Cederna PS. Overview of host defense peptides and their applications for plastic and reconstructive surgeons. Plast Reconstr Surg. 2020;146(1):91-103. doi:10.1097/PRS.0000000000006910 2. Kraus D, Peschel A. Molecular mechanisms of bacterial resistance to antimicrobial peptides. Curr Top Microbiol Immuno. 2006;306:231-235. doi: 10.1007/3-540-29916-5_9

Answer 21

The correct response is Option E. The patient described has signs and symptoms of a rapidly progressive and advancing soft-tissue infection, which is characteristic of necrotizing fasciitis. The treatment of choice is prompt operative debridement and excision of infected soft tissues and fascia. Necrotizing fasciitis is commonly polymicrobial; Group A hemolytic streptococcus and Staphylococcus aureus are the most common offending agents, although other aerobic and anaerobic bacteria are frequently involved. The infection travels along fascial planes and induces local hypoxia and profound overlying soft-tissue necrosis. Patients with necrotizing fasciitis often require repeat debridements early in the course of treatment to limit the spread of infection. Obtaining blood cultures, adding antifungal antibiotics, elevation, and ice compression do not directly address the surgical emergency of necrotizing fasciitis and would potentially delay treatment. Increasing the dosage of intravenous antibiotics would have little effect on the progression of necrotizing fasciitis. Fasciotomy of compartments is useful for a case of compartment syndrome, but not necrotizing fasciitis.

Answer 22

The correct response is Option B. Hidradenitis suppurativa (HS), also known as acne inversa, is a chronic inflammatory disease of the skin and subcutaneous structures. Initially presenting as tender, subcutaneous nodules, the disease can advance to cause abscesses and large areas of subcutaneous scarring and draining sinus tracts. Historically, HS has been thought to originate from the apocrine sweat glands. However, research in recent years has demonstrated that the mechanism is one of follicular occlusion: hair follicles become occluded due to an overproliferation of ductal keratinocytes, rupture, and subsequently re-epithelialize. As this cycle continues, sinus tracts form that house bacteria and cause chronic, painful infections and inflammation that can involve the skin and subcutaneous structures including muscle, fascia, and lymph nodes. HS lesions typically occur predominately in the apocrine-gland bearing areas of the axillary, inguinal, perianal, and perineal areas. Lesions typically correspond with the “milk-line” pattern of apocrine-related mammary tissue in mammals. Eccrine, or merocrine, sweat glands are found throughout the body, but their highest concentrations are in the palms and soles. These areas are typically spared by HS. Follicular pyodermas, including folliculitis, furuncles, and carbuncles, arise primarily from the infection of hair follicles. They do not cause the sinus tracts, comedones, and scarring caused by HS. Granuloma inguinale is a sexually transmitted infection of the genitalia, perineum, and/or perineal area caused by Klebsiella granulomatis. Pyoderma gangrenosum is a dermatologic condition mediated by neutrophils that causes skin ulceration and breakdown.

Answer 23

The correct response is Option C. The radial and ulnar bursas are connected through the Parona space, which lies between the pronator quadratus fascia and the flexor digitorum profundus tendon sheath. The flexor tendon sheath of the small finger often connects with the ulna bursa, which extends proximal to the transverse carpal ligament. This connection can give rise to a €œhorseshoe abscess. € This abscess results when an infection starting in the thumb or small finger progresses proximal through the wrist and then into the opposite flexor tendon sheath through the Parona space. The Parona space can be explored by performing an extended carpal tunnel release. Another potential space in the hand is the thenar space, which is bordered ulnarly by the vertical septum between the flexor sheath and metacarpal of the long finger, dorsally by the fascia of the adductor pollicis, and radially by the thenar muscle fascia. It should be noted that this space does not include the thenar muscles. The midpalmar space is bordered radially by the vertical septum between the flexor sheath and metacarpal of the long finger, dorsally by the fascia over the interossei of the third and fourth web spaces, ulnarly by the fascia over the hypothenar muscles, and volarly by the flexor tendons. The posterior adductor space is defined as the space dorsal to the adductor pollicis and volar to the first dorsal interosseous. The dorsum of the hand contains the posterior interosseous space, which is dorsal to the first dorsal interosseous. The ring finger would be explored if the patient had displayed signs of tenosynovitis of this digit.

Answer 24

The correct response is Option A. Medicinal leeches are still commonly used as an adjunct in the treatment of venous congestion. They secrete a powerful anticoagulant called hirudin that promotes bleeding in the congested tissues until venous outflow can be reestablished. Leeches are also known to harbor the gram-negative bacterium Aeromonas. Because leeches can be exposed to open wounds on the patient for several days during treatment, antibiotic prophylaxis against Aeromonas is recommended. Ciprofloxacin, tetracycline, trimethoprim-sulfamethoxazole (Bactrim), and third-generation cephalosporins have all been shown to be effective against Aeromonas. However, in the scenario above, all of these antibiotics have a contraindication except cefotaxime, a third-generation cephalosporin. Ciprofloxacin is contraindicated in children when a suitable alternative exists secondary to the risk of arthropathy and arthrotoxicity. Similarly, the use of tetracycline is relatively contraindicated in children owing to the potential for abnormalities with the teeth, including permanent staining and growth retardation. While Bactrim is often used in children to treat various infections, this child has an allergy to sulfa drugs and should not be given this antibiotic. Clindamycin does not provide effective antibiotic coverage against Aeromonas.

Answer 25

The correct response is Option E. The most likely diagnosis is tenosynovitis, an infection involving the gliding surface of the flexor tendon sheath that typically develops following a puncture wound. Staphylococcus aureus is the most likely causative organism. The four essential signs of tenosynovitis are fusiform swelling, partial flexed posturing of the digit, tenderness along the flexor tendon sheath, and pain with passive extension of the digit. Cellulitis is a common superficial infection that typically affects the dorsal aspect of the hand and is characterized by erythema, edema, and lymphangitis. Beta-hemolytic streptococcus is most frequently associated. Felons are infections of the pulp space (which is compartmentalized by septa) typically caused by Staphylococcus aureus. Although tenosynovitis may develop in a patient with an advanced felon, the infection is more likely to be localized at the pulp initially, and the patient would have throbbing pain, especially when the finger is placed in a dependent position. Patients with osteomyelitis have localized pain, swelling, and erythema along the course of one of the long bones of the hand. This condition often develops secondary to localized infection by hematogenous spread. In patients with paronychia, the structures surrounding the proximal and lateral nail become infected. This condition is characterized by pain, especially in the region of the nail fold, and erythema. Staphylococcus aureus is the most frequently identified cause of acute paronychia, and Candida albicans is most likely to cause chronic paronychia.

Answer 26

The correct response is Option B. The **midpalmar space** is one potential site of infection of the palm; others include the subcutaneous tissue, tendon sheaths, and thenar and hypothenar eminences. The midpalmar space is located deep to the flexor tendon. It extends dorsally to the fascia over the second and third volar interossei and the third and fourth metacarpals. The midpalmar space is bordered radially by a fascial septum extending from the third metacarpal to the flexor sheath of the flexor digitorum profundus tendon of the long finger, and ulnarly by the fascia of the hypothenar musculature. The proximal margin of the midpalmar space is a thin layer of fascia that lies just distal to the carpal canal. The distal margin of the midpalmar space is bordered by vertical septa of the palmar fascia, which extend almost to the web spaces. In patients with infection of the midpalmar space, diagnosis is often delayed. Affected patients typically exhibit swelling of the dorsal aspect of the hand, loss of palmar concavity, and difficulty extending and flexing the fingers. Marked tenderness in the midpalmar area is characteristic, and cellulitis is often associated. The thenar space is located radial to the vertical septum between the third metacarpal and the flexor digitorum profundus tendon of the long finger; it extends to the radial edge of the abductor pollicis brevis tendon. The hypothenar space contains the hypothenar muscles and is enveloped within the fascia of these muscles. It is bordered radially by a fascial septum extending from the fifth metacarpal bone to the palmar fascia.

Answer 27

The correct response is Option C. The patient described has a severe, necrotizing soft-tissue infection, as suggested by tenderness and swelling of the entire limb compartment. Urgent debridement is required. Necrotizing fasciitis must be suspected in any patient with a compromised immune system, even when he or she has a relatively small surface wound. The infection spreads along deep tissue planes €”in this scenario, the muscle fascia. Severe inflammation may result in elevated compartment pressures, requiring fasciotomy. Intraoperative bacterial cultures should guide specific antibiotic therapy. Patients with severe continued or extensive necrosis may benefit from hyperbaric oxygen (HBO) therapy. After all of the necrotic tissue is removed, vacuum-assisted compression (VAC) dressings may be applied to expedite granulation. Definitive closure may involve healing by second intention, skin grafts, or flaps as clinically indicated.

Answer 28

The correct answer is C. The patient is diagnosed with necrotizing fasciitis (type 2, monomicrobial), caused by Group A Streptococcus pyogenes. While this condition is rare following aesthetic surgery, most reported cases are associated with liposuction, and S. pyogenes is the predominant organism involved. The cornerstone of treatment includes surgical debridement and targeted antibiotic therapy with clindamycin and penicillin. Clindamycin is effective in inhibiting streptococcal toxin and cytokine production; however, it is not recommended as monotherapy initially due to the risk of clindamycin resistance. Therefore, it should be used in combination with penicillin until antimicrobial susceptibility testing guides de-escalation of therapy. Other less common type 2 infections caused by a single microorganism include methicillin-resistant Staphylococcus aureus (MRSA), Aeromonas hydrophilia, and Vibrio vulnificus. Type 1 necrotizing fasciitis is typically polymicrobial and may involve both aerobic and anaerobic bacteria. The presence of gas gangrene in type 1 infections often suggests clostridial species. Initial treatment for type 1 infections typically involves a combination of vancomycin or linezolid with piperacillin-tazobactam, a carbapenem, ceftriaxone, metronidazole, or a fluoroquinolone with metronidazole. Therapy should then be adjusted according to culture sensitivities. Vancomycin monotherapy is not recommended as an initial treatment for either type 1 or type 2 necrotizing fasciitis. 1. Marchesi, A., Marcelli, S., Parodi, P. C., Perrotta, R. E., Riccio, M., & Vaienti, L. (2017). Necrotizing fasciitis in aesthetic surgery: A review of the literature. Aesthetic Plastic Surgery, 41(2), 352-358. https://doi.org/10.1007/s00266-016-0754-2 2. Stevens, D. L., & Bryant, A. E. (2017). Necrotizing soft-tissue infections. New England Journal of Medicine, 377(23), 2253-2265. https://doi.org/10.1056/NEJMra1600673 3. Stevens, D. L., Bisno, A. L., Chambers, H. F., et al. (2014). Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the Infectious Diseases Society of America. Clinical Infectious Diseases.

Answer 29

The correct response is Option D. Infections of the index finger drain from the flexor sheath proximally into the thenar space. Infections of the long, ring, and small fingers drain into the midpalmar space. The radial and ulnar bursae communicate by Parona’s space, which lies deep to the pronator muscle.

Answer 30

The correct response is Option A. A prospective, randomized study has shown that antibiotic prophylaxis is superior to placebo in decreasing infections after human bites that are less than 24 hours old. The most common pathogens in human bite wounds are S aureus, E corrodens, H influenzae, and beta lactamase-producing anaerobic bacteria. Eikenella species are resistant to clindamycin. Meanwhile, doxycycline and trimethoprim-sulfamethoxazole are not effective against anaerobes. Of the options mentioned, only amoxicillin-clavulanate has good activity against all common oral pathogens.

Answer 31

The correct answer is option C. A recent retrospective review of 45 patients with diabetes and surgically treated hand infections noted that insulin dependence, present in 31 patients, was not statistically related to a higher likelihood of amputation. Forty-six percent of the cultures were polymicrobial, which was associated with higher amputation rate. Other factors associated with a higher amputation rate were renal failure, deep infection, and gram-negative infection.

Answer 32

The correct answer is option a. The thenar space extends from the third metacarpal to the thumb. It is contiguous with and separated from the midpalmar space by the midpalmar oblique septum. A collar-button abscess in the second web space will, like flexor tenosynovitis of the index finger, drain into the thenar space. Flexor tenosynovitis of the long and ring fingers and third web space infections will drain into the midpalmar space. Finally, small finger flexor tenosynovitis will track through the ulnar bursa and not the midpalmar space. The dorsal subaponeurotic space is just deep to the extensor tendons of the hand and does not communicate with the thenar or midpalmar spaces. Parona’s space is in the forearm between the superficial and deep flexor compartments. The natatory space is not a named space.

Answer 33

The correct response is Option C. This patient has a dystrophic nail resulting from a fungal infection (onychomycosis). The diagnosis of onychomycosis can be confirmed by positive findings on fungal culture. Fungal infections are the underlying cause of dystrophic nails in approximately 50% of affected patients; the remaining 50% are caused by other factors, including psoriasis, lichen planus, and trauma. Although they are more common in the foot, fungal infections can cause functional and aesthetic deformities in the fingernails. In the past, long-term administration of antifungal agents was recommended; however, this treatment course was associated with significant toxicity, requiring monitoring of hepatic function, and often disappointing results. More recently, terbinafine and itraconazole have offered new treatment options. This agents are administered for six weeks, and hepatic function is monitored only in those patients who have a history of hepatitis, liver disease, or heavy alcohol use. However, adverse effects associated with terbinafine use include Stevens-Johnson syndrome, neutropenia, hepatotoxicity, hepatic failure, erythema multiforme, toxic epidermal neurolysis, and anaphylaxis. In addition, terbinafine is far more costly than previously used antifungal agents. Topical or oral administration of antibiotics would not be expected to improve this fungal infection. In addition, topical antibiotics may aggravate the nail matrix. Resection of the sterile matrix and replacement with a graft is associated with a high incidence of recurrence and morbidity. Removal of the nail would not eliminate the fungal infection within the underlying matrix.

Answer 34

The correct response is Option C. This patient has chronic paronychia, which is a recurrent abscess beneath the eponychial edge of the fingernail associated with repeated exposure to a moist environment. In patients with this condition, Candida albicans is the most frequently cultured organism. Chronic paronychia can evolve following an acute episode if drainage of the abscess is inadequate or inappropriate antimicrobial agents are prescribed. Removal of a segment of nail plate is indicated in patients with acute paronychia if there is drainage beneath the plate. In a patient who has paronychia that appears to be caused by a fungal organism, management should focus on administering oral and topical antifungal agents, such as itraconazole and ketoconazole, and minimizing the moist environmental conditions that have predisposed the patient to the infection. If the infection does not respond to treatment, radiographs should be obtained to determine bony involvement. In addition, biopsy specimens and cultures of soft tissue and/or bone may be indicated to identify the pathology of the condition, as the underlying cause may be a misdiagnosed malignant tumor. If radiographs, biopsy specimens, and cultures show no disease, appropriate management is excision of the thickened dorsal nail roof (ie, marsupialization), typically a crescent-shaped piece with a width of 3 to 5 mm. Simple repeat incision and drainage alone will not prevent recurrence. Obliteration of the nail matrix or amputation of the fingertip will not address the symptoms.

Answer 35

The correct response is Option A. Adjunctive treatment in this patient should include antibiotic prophylaxis against Aeromonas hydrophila organisms. This is a symbiotic bacteria found in the intestines of medicinal-grade leeches of the Hirudo medicinalis species, which can be applied to flaps or replanted limbs in order to alleviate venous congestion. The Aeromonas bacteria produces digestive enzymes that act to break down hemoglobin within the intestines of the leech. However, patients with devitalized vascular tissue are particularly susceptible to infection with this gram-negative organism. Affected patients will develop a rapidly progressive infection with gas in the soft tissues that can resemble clostridial myonecrosis. Appropriate management consists of debridement of the affected area and administration of aminoglycoside, trimethoprim-sulfamethoxazole, or a third-generation cephalosporin. Eikenella corrodens is a facultative anaerobic gram-negative rod typically associated with human bite wounds. Penicillin or ampicillin is recommended for treatment. Histoplasma capsulatum is a fungus that results in arthralgia and arthritis in affected patients. Administration of amphotericin B is indicated. Pasteurella multocida is an anaerobic gram-negative bacillus, typically associated with cat bites and best treated with penicillin or amoxicillin with clavulanate. Staphylococcus aureus is an anaerobic gram-positive coccus present on the skin that is a frequent cause of skin and soft-tissue infections.

Answer 36

The correct response for Item 198 is Option B and for Item 199 is Option E. Septic arthritis may result from extension of an adjacent subcutaneous abscess or by intra-articular contamination caused by a laceration or puncture wound. The joint is a poorly vascularized potential space, favoring colonization. Early diagnosis and drainage are crucial to treatment, as a joint infection can progress rapidly to destruction of articular cartilage. The two most common organisms that cause hand infections are Staphylococcus aureus and B €‘hemolytic streptococci. Minor staphylococcal and streptococcal infections are treated with first-generation cephalosporins. More significant infections of the interphalangeal joint should be performed through a midaxial incision. Neisseria gonorrhoeae usually manifests as a primary venereal infection. However, it can disseminate and sometimes present as a secondary hand infection, which is often confused with a purulent tenosynovitis or arthritis. It is important to distinguish gonococcal from pyogenic infection because, unlike a pyogenic infection, a gonococcal infection does not usually destroy tendon or articular cartilage. Therefore, incision, drainage, and debridement are unnecessary and should be avoided. Disseminated gonococcal infection is the most common cause of acute infectious arthritis in sexually active adults. A history or evidence of trauma are lacking. Fluid aspiration with Gram staining for gram €‘negative diplococci allows definitive diagnosis. Hospitalization and intravenous administration of a third €‘generation cephalosporin is recommended. Manifestations of Sweet syndrome can masquerade as acute hand infections. Sweet syndrome, originally described as an acute febrile neutrophilic dermatosis, belongs to a class of skin lesions that histologically have intense epidermal and/or dermal inflammatory infiltrate of neutrophils without evidence of infection or vasculitis. The lesions can erupt at sites of minor trauma. The clinical picture is consistent with infection initially. The unresponsiveness of these lesions to antimicrobial therapy and the lack of associated cellulitis is a clue to the diagnosis. The treatment of choice involves a tapering dose of corticosteroids. Herpetic whitlows are often confused with paronychia or felon and are treated mistakenly as such. Initial signs include intense pain and erythema of the fingertip, followed by edema and tenderness. A Tzanck smear of vesicular fluid may show multinucleated giant cells. Primary herpes simplex infections typically resolve without treatment within three weeks. Incision and drainage of herpetic whitlow is contraindicated because surgical treatment converts a closed wound to open and may result in a secondary bacterial infection or viral superinfection. To date, there have been no controlled studies that assess the efficacy of acyclovir for the treatment of herpetic whitlow, but case reports suggest that it both suppresses and decreases the length and severity of recurrent infections when taken orally.

Answer 37

The correct response is Option D. The most likely diagnosis is Fournier disease. Diabetes mellitus, alcoholism, heavy smoking, leukemia, and AIDS can predispose to this condition. Common sources of infection include urogenital disease, trauma, or recent manipulation (iatrogenic trauma, ie, endoscopic procedures). Key steps in treatment include early diagnosis, intravenous hydration, and broad-spectrum antibiotics (anaerobic coverage for Clostridium perfringens should continue as it is difficult to culture this). Immediate surgical debridement along fascial plains is of utmost importance. Orchiectomy is rarely needed, as testicles have their own blood supply and are protected by external spermatic fascia. Mortality rate is quoted to be 7% to 75%, with the higher rate in patients with diabetes, alcoholism, and in cases of delayed diagnosis.

Answer 38

The correct response is Option B. Field management for frostbite includes rapid rewarming of the affected area with circulating water at 104 to 107.6 °F (40 to 42 °C) for a period of 15 to 30 minutes, protection from mechanical trauma, and appropriate analgesia. Next steps in management include elevation, antitetanus prophylaxis, debridement of clear blisters, leaving hemorrhagic blisters intact, and application of aloe vera. Penicillin should be administered for cellulitis. Adjuvant therapies can include anticoagulation, thrombolytics, hyperbaric oxygen, and sympathetic blockade; however, data to support these therapies are scant and equivocal at best. Definitive surgical amputation should be delayed for at least 3 weeks to allow for tissues to demarcate, in terms of viability.

Answer 39

The correct response is Option E. The most appropriate prophylactic regimen to prescribe in this clinical scenario is trimethoprim-sulfamethoxazole and clindamycin. Dog bites to the hand are potentially dangerous bites that could lead to serious hand infections. The common microorganisms that cause infections in such bites are Pasteurella species, anaerobes, Staphylococcus aureus, and Streptococcus. The ideal antibiotic would have been amoxicillin-clavulanic acid, which covers most of these microorganisms. However, the child is allergic to penicillin, and, therefore, this drug is contraindicated. Another good option would have been amoxicillin and clindamycin (for the anaerobic coverage). However, for the same reason described above, it too cannot be used. Tetracyclines are contraindicated in children under 8 years of age owing to the ill effects on growing teeth and bones. Quinolones are also contraindicated in children under 18 years of age owing to their harmful effects on cartilage and joints. Although this is debatable, currently the use of quinolones in children is restricted by the Food and Drug Administration to certain specific conditions (cystic fibrosis, multidrug-resistant urinary tract infection, and inhalational anthrax). Clindamycin alone does not adequately cover most of the organisms involved, including Pasteurella, which is gram-negative.

Answer 40

The correct answer is option E. Warts are more common in childhood. The rate of occurrence of common to plane warts is 20 to 1. Both can spontaneously resolve but the plana type is more likely to do so. The pathologic findings are different. Both have koilocytes, large keratinocytes with eccentric nuclei and perinuclear halo. The verruca plana lack parakeratosis and papillomatosis which are present in the vulgaris. Transformation to carcinoma has been reported with verruca vulgaris. Persons with immunosuppression are at increased risk for this change. Both forms are caused by epidermal infection with the HPV virus, the common wart from HPV types 1, 2, 4, and 7, and the plane wart from HPV types 3, 10, 27, and 41.

Answer 41

The correct response is Option C. The venom of the black widow spider (Latrodectus mactans) is a neurotoxic agent that causes the hallmark findings of muscle pain and cramping that appear within 15 minutes after the bite. This common species of spider is found throughout the United States. Most patients with latrodectism are bitten by female spiders; in contrast, the bite of the male spider rarely penetrates the skin. Affected patients have sharp pain at the wound site with two small red spots marking the location of puncture. Late findings include pain and cramping of the striated muscles, abdominal pain, vomiting, tremor, excessive salivation, and shock. In a patient who is bitten by a black widow spider, the most appropriate therapy is administration of 10 mL of 10% calcium gluconate solution over a period of 15 to 20 minutes; 1 ampule of methocarbamol or 5 mg to 10 mg of diazepam can be administered additionally. Improvement of the patient's symptoms following treatment is diagnostic of latrodectism. In immunocompromised patients, a diluted dose of black widow spider antivenin (Lyovac) should be administered intravenously at a slow rate. In contrast, the brown recluse spider produces a toxin known as sphingomyelinate, a dermonecrotic factor. Envenomation with sphingomyelinate results in hemolysis, coagulation, and platelet aggregation, often affecting fatty tissue. Symptoms can range from mild irritation to severe necrosis. Hemotoxins, such as cobra venom, are exotoxins that result in hemolysis.

Answer 42

The correct response in Option B. Staphylococcal folliculitis is the most common form of infectious folliculitis. One or more pustules may appear, usually without fever or other systemic symptoms, on any body surface. Staphylococcal folliculitis may occur because of injury, abrasion, or nearby surgical wounds or draining abscesses. The two gram-positive cocci, Staphylococcus aureus and Streptococcus pyogenes (group A), account for the majority of skin and soft tissue infections. The streptococci are secondary invaders of traumatic skin lesions and cause impetigo, erysipelas, cellulitis, and lymphangitis. S. aureus invades skin and causes impetigo, folliculitis, cellulitis, and furuncles. Elaboration of toxins by S. aureus causes the lesions of bullous impetigo and staphylococcal scalded skin syndrome.

Answer 43

The correct response is Option E. A paronychia is an infection occurring in the space between the nail plate and the paronychial or eponychial fold. Common causes include nail biting and aggressive manicuring. In an otherwise healthy individual, Staphylococcus aureus and Streptococcus species are the most common pathogens causing a paronychia. The remaining bacteria listed would only be expected to cause a paronychia in special circumstances. Enterococcus is an enteric bacterium. Mycobacterium marinum can be present in aquatic environments including fish tanks and has also been reported in the Chesapeake Bay. Pasteurella multocida is a common flora of cat mouths. Pseudomonas occurs in areas with moist environments and can be problematic in a burn unit.

Answer 44

The correct answer is option C. The diagnosis is consistent with necrotizing fasciitis with an isolate of group A strep. The primary treatment includes adequate debridement, resuscitation and metabolic support. **Pencillin** is appropriate for treating the infection and clindamycin is beneficial to the resuscitative process. Large incolums of group A Strep cause significant muscle injury due to toxin production. **Clindamycin** prevents protein toxin synthesis at the ribosomal level. It also suppresses the growth of pencillin binding proteins.

Answer 45

**The correct answer is option B.** **Rationale:** The clinical presentation is characteristic of chronic paronychia, which is primarily an irritant or contact dermatitis of the nail fold, not an infectious process. First-line treatment involves avoiding irritants and using topical corticosteroids, which have proven superior efficacy compared to topical or systemic antifungal agents. Since the patient has already failed a topical antifungal, initiating a topical corticosteroid is the logical next step. Oral antifungals (option A) and combination creams (option C) are not more effective than steroids alone. Surgical interventions (option D) and biopsy (option E) are reserved for cases refractory to medical management. **References:** 1. Tosti A, Piraccini BM, Ghetti E, Colombo MD. Topical steroids versus systemic antifungals in the treatment of chronic paronychia: an open, randomized double-blind and double dummy study. J Am Acad Dermatol. 2002;47(1):73-76. doi:10.1067/mjd.2002.122191 2. Lee DK, Lipner SR. Optimal diagnosis and management of common nail disorders. Ann Med. 2022;54(1):694-712. doi:10.1080/07853890.2022.2044511

Answer 46

The correct response is Option E. The patient described has necrotizing fasciitis and sepsis. Vibrio vulnificus is a gram-negative bacillus, a cause of necrotizing fasciitis, and is commonly associated with warm saltwater environments (Florida). It also tends to present with hemorrhagic bullae. Staphylococcus aureus is a gram-positive coccus, is not associated with watery environments, and is more commonly associated with pustules rather than hemorrhagic bullae. Clostridium perfringens is a gas-forming, gram-positive bacillus, and is associated with marine sediment. Pseudomonas aeruginosa, also a gram-negative bacillus, although associated with moist environments, is more typically associated with less aggressive soft-tissue infections. Mycobacterium marinum is also associated with watery environments, but tends to affect aquarium owners with an indolent granulomatous process.

Answer 47

The correct response is Option D. Tenosynovitis is a bacterial infection within the sheath of the extrinsic flexor tendons of the hand. Suppurative infection of the sheath can develop over time. Classic signs of tenosynovitis include fusiform swelling, partial flexed posturing of the digit, and tenderness along the flexor tendon sheath; however, other inflammatory processes can cause these findings. In contrast, the fourth classic sign, pain with passive extension of the digit, is the most sensitive test for flexor tenosynovitis. Aspiration of the affected tendon sheath will yield purulent drainage. Diagnosis can be confirmed with Gram's stain. In patients with established tenosynovitis, the most appropriate management is surgical irrigation and/or drainage of the tendon sheath. This is best accomplished with a proximal incision at the level of the A1 pulley and a distal incision at the distal flexor crease; the fibroosseous canal is then irrigated copiously. In patients with more extensive infection, open drainage and debridement may be required. Drainage from a finger wound is more likely to be caused by local wound infection than by tenosynovitis.

Answer 48

The correct response is Option A. Tuberculosus tenosynovitis is the most frequent tuberculosus infection in the hand. It may clinically simulate rheumatoid tenosynovitis. The most common pathogen is Mycobacterium marinum. Radiographs often show no abnormalities and pathology alone will often show only nonspecific tenosynovitis, but granulomas may be present. Cultures must be requested at 30 degrees Celsius to identify M. marinum. There are several diagnostic clues for tuberculous tenosynovitis, such as proliferative synovitis occurring in the absence of a known rheumatoid or collagen vascular disease as well as the presence of rice bodies during surgical exploration. Rice bodies are infected villous bodies on the synovial surface that break off and become trapped within the inflammatory mass. CT scan of the abdomen is sometimes recommended for women with palmar fibromatosis and arthritis because this condition may be associated with ovarian cancer. Amyloidosis can cause tenosynovitis and carpal tunnel syndrome but does not commonly produce rice bodies. Allopurinol is a treatment for gout, and potassium hydroxide stains are used to identify fungus.

Answer 49

The correct response is Option B. The most appropriate next step in management is to update this patient €™s tetanus status and observe closely for signs and symptoms of envenomation. The area of involvement should be outlined with a marking pen and the patient observed closely for progression of local tissue injury, clinical evidence of coagulopathy, and hemodynamic instability. In the United States, 99% of snake bites are caused by the Crotalidae (pit viper) family of snakes, which includes rattlesnakes, copperheads, and cottonmouths. Rattlesnake bites deliver the most potent venom and are responsible for the majority of fatalities from snake bites; however, 10% to 50% of snake bites have been reported as dry bites. Acute first aid interventions include avoiding excessive activity of the affected site, immobilization in a neutral position, and expeditious transportation to a hospital. Antivenin is not recommended for dry bites (ie, no clinical evidence of envenomation) or if envenomation appears to be mild. Anaphylaxis and serum sickness are potential significant complications of equine antivenin. The general indication for antivenin administration is progressive venom injury. This is defined as worsening local injury (eg, swelling, pain, or ecchymosis), the onset of clinical coagulopathy, or the development of systemic effects including hypotension or changes in mental status. The patient should be monitored closely because the clinical presentation can change rapidly. Antivenin therapy should be instituted if signs or symptoms of envenomation develop or progress. Debridement of the bite site and suction therapy have not been shown to be beneficial in reducing the effects of envenomation and can cause additional necrosis to the tissue under the suction cup. Arterial tourniquets are contraindicated because they may worsen tissue ischemia and necrosis. Fasciotomy should be performed only for clinical signs and symptoms of compartment syndrome. Compartment syndrome and infection from extremity bites are extremely rare.

Answer 50

The correct response for Item 198 is Option B and for Item 199 is Option E. Septic arthritis may result from extension of an adjacent subcutaneous abscess or by intra-articular contamination caused by a laceration or puncture wound. The joint is a poorly vascularized potential space, favoring colonization. Early diagnosis and drainage are crucial to treatment, as a joint infection can progress rapidly to destruction of articular cartilage. The two most common organisms that cause hand infections are Staphylococcus aureus and B €‘hemolytic streptococci. Minor staphylococcal and streptococcal infections are treated with first-generation cephalosporins. More significant infections of the interphalangeal joint should be performed through a midaxial incision. Neisseria gonorrhoeae usually manifests as a primary venereal infection. However, it can disseminate and sometimes present as a secondary hand infection, which is often confused with a purulent tenosynovitis or arthritis. It is important to distinguish gonococcal from pyogenic infection because, unlike a pyogenic infection, a gonococcal infection does not usually destroy tendon or articular cartilage. Therefore, incision, drainage, and debridement are unnecessary and should be avoided. Disseminated gonococcal infection is the most common cause of acute infectious arthritis in sexually active adults. A history or evidence of trauma are lacking. Fluid aspiration with Gram staining for gram €‘negative diplococci allows definitive diagnosis. Hospitalization and intravenous administration of a third €‘generation cephalosporin is recommended. Manifestations of Sweet syndrome can masquerade as acute hand infections. Sweet syndrome, originally described as an acute febrile neutrophilic dermatosis, belongs to a class of skin lesions that histologically have intense epidermal and/or dermal inflammatory infiltrate of neutrophils without evidence of infection or vasculitis. The lesions can erupt at sites of minor trauma. The clinical picture is consistent with infection initially. The unresponsiveness of these lesions to antimicrobial therapy and the lack of associated cellulitis is a clue to the diagnosis. The treatment of choice involves a tapering dose of corticosteroids. Herpetic whitlows are often confused with paronychia or felon and are treated mistakenly as such. Initial signs include intense pain and erythema of the fingertip, followed by edema and tenderness. A Tzanck smear of vesicular fluid may show multinucleated giant cells. Primary herpes simplex infections typically resolve without treatment within three weeks. Incision and drainage of herpetic whitlow is contraindicated because surgical treatment converts a closed wound to open and may result in a secondary bacterial infection or viral superinfection. To date, there have been no controlled studies that assess the efficacy of acyclovir for the treatment of herpetic whitlow, b

Answer 51

The correct response is Option B. The most appropriate antibiotic prophylaxis for this patient with a Gustilo grade III fracture is a third generation cephalosporin. Although much debate exists regarding antibiotic prophylaxis in open tibial fractures, it is generally accepted that antibiotic prophylaxis reduces the rate of infection. When antibiotic prophylaxis is not used, infection occurs in approximately 24% of open fractures. Thus, selecting the appropriate antibiotic, as well as duration, is of utmost importance. Antibiotic prophylaxis should be administered as soon as possible after injury and should be limited to a 72-hour course. In general, broad-spectrum antibiotics and multiple antibiotics should be avoided because they have been shown to increase the risk of nosocomial infections, including pneumonia. Of the antibiotics listed, the most appropriate choice for a patient with no drug allergies is ceftriaxone. Clindamycin and vancomycin should be reserved for cases of true penicillin allergy. Ciprofloxacin alone has been shown to be inferior to prevent infection after open tibial fractures.

Answer 52

The correct response is Option C. The currently accepted decolonization protocol from the Infectious Diseases Society of America is a combination of topical nasal mupirocin ointment and a chlorhexidine body wash for 5 days. The most robust data for decolonization are in the cardiac surgery literature; the Society of Thoracic Surgeons guidelines recommend routine prophylaxis for all patients undergoing cardiac surgery. These guidelines are based on studies that show a decreased rate of sternal wound infections. The carriage rate of methicillin-resistant Staphylococcus aureus for health care workers is approximately 5% based on large review studies. As a substantial portion of cases originate from nasal colonization, routine screening and decolonization are recommended in areas where the carriage rate exceeds 10% (Centers for Disease Control and Prevention recommendation). The other antibiotics listed are reserved for the treatment of infection rather than as part of a decontamination protocol.

Answer 53

The correct response is Option B. Rhinocerebral mucormycosis is a rare opportunistic infection of the sinuses, nasal passages, oral cavity, and brain caused by saprophytic fungi. The infection can rapidly result in death. Rhinocerebral mucormycosis commonly affects individuals with diabetes and those in immunocompromised states. The diagnosis of mucormycosis is established by obtaining a biopsy specimen of the involved tissue, and frozen tissue samples should be immediately evaluated for signs of infection. Microscopic characterization of non-septate hyphae, rhizoids, columellae, sporangia, and sporangiospores helps to define genus and species within the order Mucorales. Optimal therapy requires a multidisciplinary approach that relies on prompt institution of appropriate antifungal therapy with amphotericin B (AmB), reversal of underlying predisposing conditions, and, where possible, surgical debridement of devitalized tissue. Surgery should be considered early, and if possible, emergently with the goal of removing all necrotic tissue. Repeated debridements are frequently necessary and the extent of surgery should ideally be guided by evaluation of frozen tissue sections examined histologically. In the scenario provided, orbital involvement will most likely require sacrifice of the eye.

Answer 54

The correct answer is option C. The organism most likely involved is atypical mycobacteria, mycobacterium marinum. It histologically has noncaseating granulomas and stains positive on Ziehl-Neelsen staining. It is grown for four to six weeks on Löwenstein-Jensen medium at 30°C. Several months of treatments are required.

Answer 55

The correct response is Option B. The patient described has an occupation that exposes him to contaminated water and raw seafood. Infections from Mycobacterium marinum and Vibrio vulnificus are both possible. Mycobacterium marinum is the most common atypical mycobacterium seen in hand infections, often seen after penetration by aquatic equipment, colonized marine life, or contact with contaminated water. The most common deep infection is flexor tenosynovitis, and may present as a chronic tenosynovitis. Sporothrix schenckii is a fungus found in plants and soil. Inoculation with the pathogen results in a papule at the entry site, followed by development of lesions along the lymphatic chain. Suppurative flexor tenosynovitis typically presents with pain over the tendon sheath, semiflexed position of the involved digit, pain on passive extension, and symmetrical swelling of the finger. This classic presentation is commonly caused by pathogens such as Staphylococcus aureus or Eikenella corrodens (often seen in association with human bite injuries). In tenosynovitis infections involving atypical mycobacterium, however, there is absence of pain. Vibrio vulnificus is a species of gram-negative, motile, curved bacterium found in the coastal waters of the United States. Infections from V vulnificus may be caused by direct exposure of an open wound to warm seawater containing the organism or from handling raw seafood or marine wildlife. Infections caused by V vulnificus result in painful cellulitis that progresses rapidly and presents with marked local tissue swelling with hemorrhagic bullae. Bacteremia with systemic symptoms is commonly seen.

Answer 56

The correct response is Option E. The Centers for Disease Control and Prevention support criteria indicate that toxic shock syndrome may be diagnosed when patients present with a temperature exceeding 102°F (38.9°C), multisystems organ failure, rash, and/or multiple constitution symptoms. Exotoxin1 and exfoliative toxin-producing Staphylococcus aureus are the most common pathogen, but enterotoxin A, B, and C, producing Streptococcus pyogenes infections, yield a worse prognosis. Blood cultures may be negative for the causitive organism. Although Clostridium, Enterobactor, Pseudomonas, and Bacteroides species are polymicrobial species associated with necrotozing fasciitis, the description of this otherwise healthy patient is not consistent with its typical presentation of discolored blistered skin and crepitus.

Answer 57

The correct response is Option E. Bite injuries resulting from fistfights usually occur over the dorsal aspect of the third, fourth, or fifth metacarpophalangeal joint where a tooth penetrates the skin, extensor tendon, potentially the joint capsule, and even bone. When the hand is opened, the inoculating bacteria are dragged proximally by the extensor tendon and soft tissue. The patient may present acutely before clinical signs of an infectionCwith what appears to be a simple laceration or abrasion over the metacarpophalangeal jointCbut more typically after signs of infection have developed. If there are no signs of infection, it is prudent to explore the wound to rule out injury to the extensor tendon, joint capsule, and cartilage. To do so, the hand must be examined through the entire range of motion, particularly with the fingers flexed as in a clenched fist position. If there is no injury to the deeper structures, the wound can be washed out and the skin left open to heal by second intention. The patient can then be discharged with prophylactic antibiotics to cover the most common bacteria isolated from human bite wounds, i.e., Staphylococcus aureus, followed by Streptococcus species, Corynebacterium species, and Eikenella corrodens. Follow-up within 24 to 48 hours is important in outpatient management of these injuries. If injury is noted to the tendon, joint capsule, or joint cartilage, then operative washout and admission for intravenous antibiotics is appropriate. When the patient presents with a well-developed infection, antibiotic therapy alone is insufficient. Careful exploration must be performed to rule out injury and infection to deeper structures, most importantly the joint. Unrecognized or untreated pyarthrosis can lead to joint destruction and osteomyelitis. Inadequate exploration in the emergency department is usually due to inadequate anesthesia. Formal washout and drainage is sometimes best performed in the operating room. Elevation and immobilization are important in the management of edema in patients with hand infections. In the clinical scenario presented, however, this alone would be insufficient treatment because surgical drainage of the joint is required.

Answer 58

The correct response is Option B. Necrotizing soft-tissue infections are rapidly progressive, polymicrobial infections that require prompt diagnosis, debridement of devitalized tissue, and administration of appropriate antibiotics. Some studies have shown that mortality rates in necrotizing infections can be reduced with the addition of hyperbaric oxygen treatment. High-dose corticosteroids, intravenous gamma globulin, and topical papain-urea ointment have not been shown to increase survival rates of necrotizing soft-tissue infections.

Answer 59

The correct answer is option E. Septic arthritis may result from extension of an adjacent subcutaneous abscess or by intra-articular contamination caused by a laceration or puncture wound. The joint is a poorly vascularized potential space, favoring colonization. Early diagnosis and drainage are crucial to treatment, as a joint infection can progress rapidly to destruction of articular cartilage. The two most common organisms that cause hand infections are Staphylococcus aureus and B-hemolytic streptococci. Minor staphylococcal and streptococcal infections are treated with first-generation cephalosporins. More significant infections of the interphalangeal joint should be performed through a midaxial incision. Neisseria gonorrhoeae usually manifests as a primary venereal infection. However, it can disseminate and sometimes present as a secondary hand infection, which is often confused with a purulent tenosynovitis or arthritis. It is important to distinguish gonococcal from pyogenic infection because, unlike a pyogenic infection, a gonococcal infection does not usually destroy tendon or articular cartilage. Therefore, incision, drainage, and debridement are unnecessary and should be avoided. Disseminated gonococcal infection is the most common cause of acute infectious arthritis in sexually active adults. A history or evidence of trauma are lacking. Fluid aspiration with Gram staining for gram-negative diplococci allows definitive diagnosis. Hospitalization and intravenous administration of a third-generation cephalosporin is recommended. Manifestations of Sweet syndrome can masquerade as acute hand infections. Sweet syndrome, originally described as an acute febrile neutrophilic dermatosis, belongs to a class of skin lesions that histologically have intense epidermal and/or dermal inflammatory infiltrate of neutrophils without evidence of infection or vasculitis. The lesions can erupt at sites of minor trauma. The clinical picture is consistent with infection initially. The unresponsiveness of these lesions to antimicrobial therapy and the lack of associated cellulitis is a clue to the diagnosis. The treatment of choice involves a tapering dose of corticosteroids. Herpetic whitlows are often confused with paronychia or felon and are treated mistakenly as such. Initial signs include intense pain and erythema of the fingertip, followed by edema and tenderness. A Tzanck smear of vesicular fluid may show multinucleated giant cells. Primary herpes simplex infections typically resolve without treatment within three weeks. Incision and drainage of herpetic whitlow is contraindicated because surgical treatment converts a closed wound to open and may result in a secondary bacterial infection or viral superinfection. To date, there have been no controlled studies that assess the efficacy of acyclovir for the treatment of herpetic whitlow, but case reports suggest that it both suppresses and decreases the length and severity of recurrent infections when taken orally.

Answer 60

The correct answer is option D. The lesion demonstrated represents **pyoderma gangrenosum**, which is a cutaneous lesion manifested by skin ulceration and necrosis. The onset is acute and rapid, affecting adults 25–54 years of age. In 30%–60% of cases there is an association with ulcerative colitis. It is much more common in the lower extremity and somewhat rare in the hands. Because of the unusual nature of the lesions, appropriate treatment is often delayed. Treatment is supportive including local wound care and sometimes the use of steroids, dapsone or cyclosporine. Surgical debridement may actually cause the lesions to proliferate. Skin grafting is occasionally needed, but never done during active disease. Treatment of the ulcerative colitis, when present, will also help to resolve the lesions. The etiology is not infectious, hence antibiotic therapies are not helpful.

Answer 61

The correct response is Option B. Necrotizing fasciitis is a severe form of subcutaneous infection that tracks along fascial planes often extending beyond the superficial signs of infections. Early diagnosis and treatment are critical in reducing mortality. Early surgical intervention is often required for diagnosis and treatment. Initial antibiotic therapy is directed at the most likely pathogens. Two clinical subtypes of necrotizing fasciitis have been identified. Type I is a polymicrobial infection caused by aerobic and anaerobic bacteria occurring primarily in patients who are immunocompromised or have certain chronic diseases like diabetes. Type II is a monomicrobial infection that can occur in healthy individuals in any age group. Often, the individual has a history of blunt trauma, penetrating injuries or lacerations (often minor), surgical procedures, childbirth, or burns. In Type II fasciitis, the most common causative organisms are group A streptococci. Clindamycin and penicillin in combination are recommended. Clindamycin has been shown to suppress toxin production, whereas metronidazole has not. Clindamycin also facilitates phagocytosis of Streptococcus pyogenes. Penicillin is added because of increasing resistance of group A streptococci to clindamycin. Infection with Staphylococcus aureus is a less common cause of Type II necrotizing fasciitis. Oxacillin could be used to treat susceptible S. aureus infection, whereas vancomycin is appropriate therapy for methicillin-resistant S. aureus (MRSA). Type I necrotizing fasciitis requires a multiple antibiotic regimen to cover aerobic and anaerobic bacteria. Therefore, broad €‘spectrum coverage with ampicillin €‘sulbactam, clindamycin, ciprofloxacin, or gentamicin is recommended.

Answer 62

A) Administration of acyclovir

Answer 63

The correct response is Option E. Of the listed factors relating to risk of postoperative infection in this scenario, the strongest correlation is with contamination type. The Gustilo–Anderson fracture classification has been found to have some correlation with open fracture infection rates, but this relationship is not as strong in the distal radius as it is in long bones of the lower extremity. Recent studies by Glueck, et al, and Swanson, et al, have shown that contamination is a much stronger correlate. A history of systemic illness, such as diabetes mellitus, and the type of fracture fixation seem to have a modest correlation to postoperative infections in distal radius fractures, but the findings are generally not statistically significant. The timing of the initial debridement, as long as it occurs within the first 24 hours of injury, does not significantly affect infection rate. In contrast, there is evidence to suggest that performing multiple serial debridements in significantly contaminated wounds is of benefit in preventing postoperative infection.

Answer 64

The correct answer is option C. This is an example of a chronic paronychial infection. There is usually no single causative organism hence long term antibiotics may not be successful. Although diabetes may be implicated, control of the blood sugars by itself will not be curative. Similarly, avoidance of maceration is important but not enough by itself. In this case Zook recommends a marsupialization of the nail fold ,which consists of excision an ellipse of skin proximal to the nail bed with secondary healing. Avoiding chronic water immersion and controlling abnormal blood glucose levels are appropriate measures but they will not by themselves result in a resolution of this chronic condition.

Answer 65

The correct response is Option A. Cat bites usually result in puncture wounds because of their long, slender, sharp teeth. It has been reported that as many as 80% of cat bites become infected. Pasteurella species are the most common, occurring in as many as 75% of cat bite infections. Other types of bacteria can also be involved as well, including Streptococci, Staphylococci, and anaerobes. Appropriate antimicrobial treatment for bite wounds must take into account the usual bacteriology of these infections. Pasteurella species are susceptible to penicillin, ampicillin, second- and third-generation cephalosporins, doxycycline, trimethoprim-sulfamethoxazole, fluoroquinolones, clarithromycin, and azithromycin, but are resistant to cephalexin, dicloxacillin, erythromycin, and clindamycin. Appropriate choices for prophylaxis and treatment of cat bite wounds would include amoxicillin and clavulanate or a combination of penicillin plus cephalexin. For those patients who have an allergy to penicillin, moxifloxacin or combination therapy with ciprofloxacin and clindamycin are appropriate choices. Azithromycin may also be effective for the penicillin-allergic patient, but it has less activity against anaerobes. Coverage for community-acquired MRSA (CA-MRSA) infection is not recommended because oral colonization of the human and animal mouth with CA-MRSA is unlikely. Cefazolin, an intravenous form of a first-generation cephalosporin, is not an appropriate treatment for this wound as Pasteurella species are resistant, just as they are to cephalexin, the oral form.

Answer 66

The correct response is Option D. The specific treatment of an extravasation injury is dependent on the drug infused. Application of topical dimethyl sulfoxide has been advocated for the treatment of extravasation of anthracyclines and is supported by several studies. The value of hyperbaric oxygen therapy has not been proven. In the case of doxorubicin extravasation injury, cold compresses may exacerbate the complication by venous constriction, which localizes the drug, whereas hot packs may cause vasodilatation with further extravasation. Inflammation and pain can be managed with anti-inflammatory analgesics. Early excision is rarely performed without evidence of at least ulceration, and the main indication would then be for pain control. In the scenario described, an option would be early surgical debridement and delayed closure of the wound; however, some of the surrounding skin may heal. Thus, a conservative initial approach with later excision after 2 to 3 weeks is recommended since this will give a better cosmetic result.

Answer 67

The correct response is Option E. Infectious flexor tenosynovitis can spread from the tendon sheath of the fifth digit to the flexor tendon sheath of the thumb by way of the space of Parona: the potential space in the volar wrist, deep to the flexor tendons but superficial to the pronator quadratus muscle. In this area, the proximal extent of the tendon sheaths of both the small finger and the thumb are in close proximity. This has been termed the “horseshoe abscess” of the upper extremity.

Answer 68

The correct response is Option E. Staphylococcus is still the most common organism in hand infections. The most common in felons is Staphylococcus aureus. Methicillin-resistant Staphylococcus aureus community-acquired (MRSA-CA) infections are now the most predominant strain in hand infections, comprising 60% of Staphylococcus aureus infections. Pasteurella multocida should be considered with most animal bites, although it is most common with cat bites. Eikenella corrodensis associated with human bites. There is no history of bites in this case. Listeria monocytogenes has been reported in flexor tenosynovitis in immunocompromised patients. Candida albicans is usually associated with chronic paronychia.

Answer 69

The correct response is Option E. This 48-year-old nurse has findings consistent with streptococcal toxic shock syndrome caused by invasive infection with Streptococcus organisms. This condition is characterized by pain disproportionate to the level of injury. Affected patients typically have other minor symptoms, in addition to pain, and have been known to seek treatment frequently before the correct diagnosis is established. Streptococcal toxic shock syndrome is confirmed by the presence of coagulation difficulties and hepatic and renal abnormalities. Clostridial necrotizing fasciitis has symptoms similar to streptococcal toxic shock syndrome but is differentiated by subcutaneous emphysema and air in the tissues on radiographs. With anthrax contamination, primary routes of inoculation are cutaneous and inhalational. Cutaneous anthrax is characterized by a single lesion that initially resembles an insect bite but then becomes ulcerated. Skin trauma is not associated. Pseudomonas ecthyma gangrenosum is an infection that demonstrates rapid progression and is frequently fatal. It occurs in patients with febrile neutropenia, and is often a complication of chemotherapy administered for lymphoreticular malignancies. Although staphylococcal cellulitis is not associated with systemic manifestations, patients with staphylococcal toxic shock syndrome can have failure of multiple organ systems.

Answer 70

The correct response is Option B. Necrotizing fasciitis is a rapidly progressive soft-tissue infection. Patients usually present with systemic sepsis, fever, high leukocytosis (higher than 25,000), skin findings of edema with blue discoloration, weeping blisters and cellulitis. The more severe cases can present with multisystem organ failure and altered mental status. Polymicrobial infections are most common. Streptococcal species are isolated in more than 60% of polymicrobial infections. Other organisms identified include Staphylococcus aureus, Escherichia coli, Pseudomonas, Enterobacter, Klebsiella, Proteus, Bacteroides, Clostridium, and Peptostreptococcus. Multiple studies have reported a mortality rate of approximately 20% from necrotizing fasciitis. Mortality is directly proportional to time of intervention. Delayed surgical debridement has been shown to significantly increase the mortality risk. After diagnostic delay, the most common pitfall in treatment is inadequacy and delay in surgical debridement. Type 2 diabetes mellitus is incorrect. Comorbid conditions such as diabetes, vascular disease and venous insufficiency are very common in these patients. Diabetes specifically is associated with higher morbidity and mortality. Studies have shown that patients with diabetes have a higher chance of a negative outcome compared to patients without diabetes. However, it has not been shown to be the most severe risk factor associated with mortality. Smoking is incorrect. Smoking is a risk factor for delayed healing, but there are no studies that show smoking alone to be a risk factor in the progression of necrotizing fasciitis. After delay of operative debridement, immunosuppression is the second most significant risk factor for mortality. Patients with solid organ transplantation or undergoing treatment for hematologic malignancies are most at risk. Age has been reported as another risk factor of mortality in patients with necrotizing fasciitis. Studies have shown that extremes of age, younger than 1 year or older than 60 years, were associated with mortality, but age is not the strongest risk factor among the others reported.

Answer 71

The correct response is Option C. Orbital cellulitis may be caused by local extension of a superficial infection such as a hordeolum, or from adjacent infected sinuses, or by hematogenous seeding from a dental or facial abscess. It is important to distinguish between preseptal and orbital cellulitis, which should be suspected when unilateral proptosis is present, and to identify the presence of an intraorbital abscess. Infection within the orbit has implications for management and prognosis due to the effect of high mechanical pressures generated in an unyielding compartment, which will manifest as proptosis, and other symptoms including diplopia, ophthalmoplegia, and chemosis. Orbital cellulitis requires hospitalization and prompt initiation of parenteral antibiotics. An intraorbital abscess can form if treatment is delayed, further compounding the intraorbital pressure and causing tissue necrosis. An intraorbital abscess requires immediate surgical drainage due to risk of blindness. Preseptal cellulitis is an infection of periorbital tissues superficial to the orbital septum, and if the source is from a nearby superficial skin infection, then initial management may be done with oral antibiotics and close follow-up. Preseptal cellulitis from a hematogenous source is more likely to become complicated with orbital cellulitis and abscess if it is not managed with parenteral antibiotics. Infections inside the orbit may extend to the central nervous system and may also cause cavernous sinus thrombosis. CT scan or MRI will confirm intraorbital infection, and related sources such as a facial or dental abscess or a sinusitis, and can direct the surgeon to areas requiring surgical drainage. Blood cultures are useful in identifying the causative organism of the infection during periods of bacteremia, and are an appropriate test in the general workup of the patient; however, blood cultures alone do not diagnose or exclude intraorbital infection. Cell counts are also useful in the general workup of the patient to characterize the systemic impact of the infection, and to be used as a guide in the responsiveness to treatment. The counts do not diagnose or exclude intraorbital infection specifically. On Waters view x-ray studies, increased facial or eyelid edema may be seen as a slight diffuse opacification, but they are unable to delineate orbital and periorbital soft tissues individually. Sinus opacification can be suggestive of active sinusitis and a potential cause of orbital cellulitis. In general, plain x-ray study offers far less information than CT scan or MRI and is not diagnostic of intraorbital infection. Wound swabs are helpful in identifying the causative organism of the infection when there is an obvious source, and are an appropriate test in the general workup of the patient; however, wound swabs alone do not diagnose, exclude, or characterize the extent of intraorbital infection.

Answer 72

The correct response is Option A. Apocrine glands are associated with sweat production and when mixed with bacteria produce body odor, which can be malodorous. There are two types of sweat glands, eccrine and apocrine. Eccrine glands are located throughout the body and secrete primarily water and salt. Apocrine glands are located in hair-bearing areas such as the axilla and groin and secrete watery fluid that is higher in protein. There are three types of exocrine secretion. Merocrine glands secrete via exocytosis and no part of the glands is damaged or lost. Eccrine glands are a type of merocrine gland. Apocrine glands secrete via membrane budding and loss of cytoplasm. The mammary glands are a type of apocrine gland. Finally, holocrine glands secrete via membrane rupture, which destroys the cell. Examples include sebaceous glands, which contain remnants of dead cells, as well as meibomian glands of the eyelids. Hyperhidrosis describes excessive sweating through the eccrine glands where there is an increase in number and size of these glands. Osmidrosis, or bromhidrosis, involves excess secretion of the apocrine glands combined with bacterial proliferation with corynebacterium. Enzymatic breakdown of the glandular secretions results in the malodor.

Answer 73

The correct response is Option C. Given the patient’s history of diabetes and necrotizing non-purulent infection after minimal trauma, he is likely to have mucormycosis, a life-threatening fungal infection caused by organisms from the class Zygomycetes. On microscopy, tissue samples from patients with mucormycosis demonstrate right-angle nonseptate branching hyphae. Grape-like clusters of gram-positive bacteria is not appropriate. This option describes the characteristic appearance of a staphylococcal infection. Given the patient’s lack of cellulitis or purulent infection, it is an unlikely mechanism for this necrotizing ulceration. Septate nonbranching hyphae and yeast forms is not appropriate. This option describes the characteristic appearance of a candidal infection. Given the patient’s lack of marked erythema and excoriation, and location of the infection on the face, rather than in skin folds, the likelihood of Candida as the primary pathogen is extremely low. Chain-like collections of gram-positive bacteria is not appropriate. This option describes the characteristic appearance of a streptococcal infection. Although streptococcal infections are common in the head and neck region, the patient’s history and appearance of the lesion do not support Streptococcus as the causative organism. Tiny yeast forms with occasional unequal bud formation is not appropriate. This option describes the characteristic appearance of Histoplasma capsulatum, an opportunistic fungus, which may cause marked pulmonary infections in immunocompromised patients. Often emergent debridement is required, and that decision will need to be made on Gram stain, not on final culture.

Answer 74

The correct response is Option D. In this patient who has septic arthritis affecting the proximal interphalangeal joint of the index finger, the most likely cause is infection with Staphylococcus aureus organisms. Staphylococcus aureus is an anaerobic gram-positive coccus that is present on the skin and is a frequent cause of skin and soft-tissue infections. It is the most common cause of septic arthritis of the hand and wrist. Eikenella corrodens, an anaerobic gram-negative rod, is present in the human mouth and is more likely to be cultured from a human bite wound. Septic arthritis resulting from Neisseria gonorrhoeae is more likely to occur in young men who are sexually active. Affected patients typically have a history of migratory polyarthralgia. Serratia species are a frequent cause of infection in persons who abuse intravenous drugs as well as patients with diabetes mellitus or immune system compromise. Streptococcus species, including viridans streptococcus, are the second most common causative organism in patients with septic arthritis of the hand.

Answer 75

The correct response is Option C. This 6-year-old boy has purpura fulminans, an uncommon illness that typically affects young children but can also occur in adults. Purpura fulminans often develops in association with a predisposing condition. It manifests as severe hemorrhage and necrosis of skin associated with disseminated intravascular coagulation. Affected patients have petechial rashes, which progress to confluent areas of ecchymosis, and then to necrotic, hard, full-thickness eschar. Bilateral symmetric gangrene of the extremities necessitates amputation in as many as 20% of patients. Reconstructive procedures, including free tissue transfer, are frequently required to resurface necrotic areas and salvage extremities with exposed joints. Septic shock and organ failure may also result. Mortality rates have been reported to be as high as 60%. Purpura fulminans is associated with endotoxin-producing bacteria. Although Neisseria meningitidis is the most common causative organism, Streptococcus pneumoniae, Haemophilus influenzae, and Rickettsia have also been implicated. The mechanism of this condition is believed to be liposaccharide-mediated endothelial damage caused by bacteria, leading to decreased serum levels of proteins C and S. Skin necrosis results from a low-flow coagulative state and microemboli. Management of affected patients includes general hemodynamic support, intravenous administration of an appropriate antibiotic, wound care, eventual soft-tissue reconstruction, and amputation when necessary.

Answer 76

The correct response is Option E. Given the obvious devitalized tissue in the associated photograph, the most appropriate next step would be further debridement. This is an often overlooked, but still critical, cornerstone to reconstruction, because without it, complication rates from infection are significantly increased. Debridement involves the removal of nonviable or contaminated tissue that impedes normal tissue growth. It renews the wound and surrounding tissue to promote normal healing by removing infection, biofilm, and senescent cells. Different debridement options are available, including mechanical, biologic, technical, and surgical methods. In this acute scenario with an otherwise healthy patient and a large amount of devitalized tissue, surgical debridement is the most appropriate choice. All other modalities/choices are not appropriate until the wound bed is stabilized. Negative pressure wound therapy may be used in conjunction with debridement, but is not a replacement for it.

Answer 77

The correct response is Option E. The CDC defines a surgical site infection as an infection that occurs at the incision site or within the organ or space operated on within 30 days after surgery or within 1 year if a prosthetic implant is placed. Infection requires at least one of the following: Purulent drainage from the surgical site Organisms isolated from an aseptically obtained culture of fluid or tissue at the surgical site Spontaneous dehiscence of a deep incision or deliberate opening of the incision by a surgeon when the patient has at least one of the following signs or symptoms: fever (greater than 100.4°F [38.0°C]), localized pain or tenderness, localized swelling, redness, or heat, unless site is culture-negative An abscess or other evidence of infection involving the incision or operative site that is found on direct examination, during reoperation, or by histopathologic or radiologic examination Diagnosis of a surgical site infection by a surgeon or attending physician

Answer 78

The correct response is Option C. The patient described has a web space (collar-button) abscess. Pus resides dorsal to and volar to the natatory fibers of the palmar fascia with a small connection between the two spaces passing through the natatory fibers. It is drained through proximal dorsal and volar incisions in the web space. One should not incise through the apex of the web space, as this may lead to a web space contracture. Incisions are allowed to heal by secondary intention. Cleland ligament is a separate portion of the palmar fascia located within the finger dorsal to the neurovascular bundle. It is distal to the purulence in a web space abscess. Absence of pain with axial loading of the digits makes a joint space infection unlikely, so drainage of the metacarpophalangeal joint is unnecessary. Some approaches to drainage of flexor tenosynovitis involve release of the proximal sheath through the A1 pulley; the appearance in the photo (lack of fusiform swelling), and absence of pain with passive extension of the fingers, make flexor tenosynovitis unlikely in this patient. Infection of the mid-palmar space would produce more proximal pain and swelling in the palm, which is not present in this patient.

Answer 79

The correct response is Option D. The most appropriate next step in management is to surgically explore the wound in the operating room. The clinical picture is of a severe, rapidly progressing infection, possibly necrotizing fasciitis. A high index of suspicion and early treatment are vital for successful outcomes. Necrotizing fasciitis is a rare and rapidly progressive infection of the deeper layers of skin and subcutaneous tissues, easily spreading across the superficial fascial plane, with subsequent death of the overlying skin and severe systemic toxicity. Liposuction is the most frequently associated cosmetic surgery with this infection. Signs and symptoms are insidious, nonspecific, or virtually unnoticeable early in the course of the disease. Later, erythema, prominent edema, and induration appear, accompanied by intense or intolerable pain. The clinical picture evolves into systemic toxicity and eventually multiple organ failure. Risk factors for necrotizing fasciitis include diabetes mellitus, immunosuppression, age older than 50 years, malnutrition, and peripheral vascular disease. There are two forms of the disease: one caused by Streptococcus pyogenes, and the other by mixed infections caused by a variety of microbes, including Escherichia coli, Proteus, Serratia, and Staphylococcus aureus. The progressive necrosis of the tissues typically involves the superficial fascia and the subcutaneous layer. The extent of the gangrene at the fascial layer is typically more severe and greater than at the skin level. This insidious infection is virtually unnoticeable and nonspecific in the first 24 to 48 hours; however, in the following days, an extensive, hardened area appears, which is often dark colored in the center. Intense pain and skin necrosis follow at the level of the infection. Metabolic changes occur, ending with respiratory distress, oliguria, acidosis, increased creatine kinase activity, increased troponin concentrations, and toxic syndrome. Diagnosis and treatment consists of surgical exploration and debridement that reveal necrotic, edematous subcutaneous fat. Bacteriologic analysis of exudate, cultures, and histologic evaluation complete the diagnosis. Early diagnosis is imperative to avoid a fatal outcome. Because necrotizing fasciitis is a progressive, rapid infection, a staged “second-look” operation and, if necessary, additional debridement should be performed. The mortality rates are high and range from 20 to 70%, but decrease to 4.2% after immediate surgical intervention. Though antibiotic therapy is an integral part of the treatment, surgical exploration is key. CT scans and ultrasonography will not change the treatment plan and are therefore not the appropriate next step in management.

Answer 80

The correct response is Option B. The most appropriate next step in management is to initiate intravenous dexrazoxane. Recent data support the use of this agent in extravasation of anthracyclines (e.g., doxorubicin) as an antidote. It has been shown to decrease the frequency and severity of tissue injury. The mechanism by which dexrazoxane diminishes tissue damage is unknown. However, two mechanisms of action are hypothesized: 1) reduction of oxidative stress due to complexes of metal ions and anthracyclines by chelating metal ions; 2) and blockade of topoisomerase II poisons by catalytic inhibition of topoisomerase II. Patients receive treatment with dexrazoxane 1000 mg/m2 administered intravenously on days 1 and 2, and 500 mg/m2 on day 3. The infusion is given in the opposite arm of the extravasation site and is administered as soon as possible and no longer than 6 hours after the extravasation accident. Flushing the port is not indicated because the port may be malfunctioning and this action could extravasate the flushing agent. Adding more fluid to the area (extravasation of saline from the port, subcutaneous saline injection, etc.) will only add to the pressure on the overlying skin, injuring the skin further. Removal of the port is not indicated until it has been ascertained it is malfunctioning. Dimethyl sulfoxide (DMSO) is a known treatment option for anthracycline extravasations. However, it is used as a topical agent with or without cortisone, not as a subcutaneous injection. Additionally, it should not be used in patients who are receiving dexrazoxane because it has been shown to decrease the efficacy of the dexrazoxane therapy.

Answer 81

Correct answer is option C. When disseminated to the hand, *coccidiomycosis* usually presents as tenosynovitis in adults and osteomyelitis in children. Anywhere from 100 to 500 new disseminated cases per year come from *Arizona, New Mexico, and surrounding area*. *The Mississippi & Ohio River valley* is endemic for both *blastomycosis and histoplasmosis*. Most patients with blastomycosis present with skin lesions, typically to the dorsum of the hand, and histoplasmosis may present as flexor tenosynovitis. *Sporothrix schenckii* is a ubiquitous soil saprophyte, which is not restricted to northern latitudes but often encountered among farmers, gardeners and florists. Distal puncture wounds cause local subcutaneous nodules that may ulcerate. More proximal lesions appear along lymphatic channels over a course of several weeks. Bone involvement does not usually occur in sporotrichosis. Chromomycosis represents infections from five genera of dematiacious fungi, which typically cause superficial mycosis of the upper extremities in the tropics.

Answer 82

The correct response is Option E. The infection described is most likely caused by a subset of Staphylococcus aureus, which is methicillin €‘resistant. Although methicillin €‘resistant S. aureus (MRSA) has traditionally been iatrogenic in its etiology, community €‘acquired MRSA is becoming more prevalent. In the Emergency Department population, the proportion of soft tissue infections presenting with MRSA is increasing. MRSA is not sensitive to penicillin €‘related antibiotics such as piperacillin/tazobactam and typically requires vancomycin or linezolid for effective treatment. Older antibiotics such as clindamycin and trimethoprim €‘sulfamethoxazole may also be effective in treating MRSA. MRSA takes longer than the other bacteria listed to grow out in culture. Bacteroides fragilis, Escherichia coli, group B streptococcus, and Pseudomonas aeruginosa are all common bacteria found in abscesses of the hand; however, they are all sensitive to penicillin €‘related antibiotics such as piperacillin/tazobactam.

Infections - Soft Tissue - Hand Flashcards

(106 cards)