Microbiology

Question 1

____ ___ is the most common cause of osteomyelitis in the general population. In the intravenous drug using population, __ ___ should also be considered, although it is still less than ___ ____.

Answer 1

S. Aureus is the most common cause of osteomyelitis in the general population. In the intravenous drug using population, P. Auriginosa should also be considered, although it is still less than S. Aureus

Question 2

__ ___ can cause Pott’s Disease

Answer 2

M. Tuberculosis

Question 3

__ __ can cause white thick discharge and lead to PID in women. It is a rare cause of osteomyelitis in sexually active people, but more often results in septic arthritis

Answer 3

N. Gonorrhea

Question 4

___ is osten seen as a cause of osteomyelitis in people with sickle cell disease

Answer 4

Salmonella

Question 5

A 5-year-old girl visiting from Nicaragua is brought to the emergency department by her aunt because of a sore throat and general malaise for the past 3 days. Physical examination reveals temperature of 38°C (100.4°F) and a grayish-white membrane on the pharynx that bleeds on attempted dislodgement.

What is the most appropriate culture media for diagnosing this patient?

Answer 5

Loeffler’s Media or Tellurite Media

This patient has diptheria, and infection caused by a gram posittive rod.

C. Dip presents as a gray-whte exudate on oral-pharynx. Fever is usually mild or absent. It is rarely seen in the U.S. because of vaccination.

Question 6

What is the most appropriate culture for:

1. Bordatella
2. Neisseria Gonorrhoaea
3. Fungi
4. Chocolate agar with factors V and X

Answer 6

What is the most appropriate culture for:

1. Bordatella - Bordet-Gengou
2. Neisseria - Thayer-Martin (VPN)
3. Fungi - Sabourand Agar (Sab’s a FUN GUY)
4. Chocolate agar with factors V and X - H. Influenza (Phyliss’ Chocolate Shop)

Question 7

A 23-year-old woman returns from a week swimming at the beach and presents to her physician with a complaint of pain in her right ear. Her temperature is 38.7°C (101.7°F), pulse is 98/min, and blood pressure is 128/85 mm Hg. Physical examination reveals an area of redness extending from her right ear toward her right mandible that is warm to the touch. There is tenderness on manipulation of the right pinna but not of the left. The right tympanic membrane is not visualized because of pain, but the left tympanic membrane is normal. The patient’s oropharynx is without exudates or erythema.

What is the most likely pathogen causing these symptoms?

Answer 7

P. Auriginosa

The patient has otitis externa, which often occurs after swimming. Otitis externa typically presents with ear pain, pruritis, discharge and pain on manipulation of the pinna. Periauricular cellulitis and fever are signs of more serious infection. As opposed to otitis media, there is typically no evidence of middle ear fluid. Pseudomonas aeruginosa is the most common cause of otitis externa (39% of cases), followed by Staphylococcus epidermidis (around 9% of cases).

Question 8

Moraxaella Catarrhalis cause otitis ___

Answer 8

interna

Question 9

___ ___ is a gram-positive organism that is the most common cause of otitis media, not otitis externa.

Answer 9

Streptococcus pneumoniae is a gram-positive organism that is the most common cause of otitis media, not otitis externa. Although it can indeed cause otitis externa, S. pneumonias is a much less common causal organism than P. aeruginosa (only observed in around 9% of cases).

Question 10

__ __ is the most common cause of otitis externa

Answer 10

P. Auriginosa

Question 11

A 12-year-old boy presents to his pediatrician with a 3-day history of watery, nonbloody, foul-smelling diarrhea. He has had some nausea, malaise, and bloating but remained afebrile during this period. His family recently returned from a vacation during which they spent a day in Tijuana, Mexico. The pediatrician suspects infection with ___ ___

The physician can diagnose this by seeing which of the following?

Answer 11

Giardia

Trophozoite in stool

Question 12

T/F

Amebic colitis increaed eosinophilia

Answer 12

False

This patient has dysenteric colitis caused by infection with the parasite Entamoeba histolytica. Amebiasis (indicated in the image by the typical flask-shaped ulcer in the intestinal mucosa) is transmitted via the fecal-oral route and is prevalent in tropical countries with poor sanitation. It can affect the intestines and/or liver by invading the portal vein and producing hepatic abscesses, which cause right upper quadrant pain. Intestinal manifestations include recurrent episodes of diarrhea containing mucus and/or blood, and abdominal pain. In severe colitis, patients can have fever, ileus, peritonitis, and hemorrhage. Laboratory diagnosis is achieved by detecting amoebas or E. histolytica antigen in a stool sample or liver abscess aspirate. Though eosinophilia is seen in helminth infections, it is not associated with E. histolytica infection.

Question 13

Diverticulitis presents with __ ___ quadrant pain, constipation, and rectal bleedig.

Answer 13

Lower left quandrant pain

Question 14

__ __ is the most common cause of bloody diarrhea in the U.S. Epidemics have been assoxiated with the consumption of raw chicken and unpasteurized milk.

Infection will cause loose, bloody stools, fever, and abdominal pain. It can also redust in asending paralysis.

Mucus in the stool and eosinophilia are/are not a common feature.

Answer 14

C. Jejuni is the most common cause of bloody diarrhea in the U.S. Epidemics have been assoxiated with the consumption of raw chicken and unpasteurized milk.

Infection will cause loose, bloody stools, fever, and abdominal pain. It can also redust in asending paralysis.

Mucus in the stool and eosinophilia are not a common feature.

Question 15

Yersinia Enterocolitic is in the differential diagnosis for bloody diarrhea. It affects young children (age 1-4) and has been associated in daycares. The transmission is __ __. It has a unique ___ stain, is gram ___, and is ___ resistant. You can treat it with __ or __

Answer 15

Yersinia Enterocolitic is in the differential diagnosis for bloody diarrhea. It affects young children (age 1-4) and has been associated in daycares. The transmission is fecal-oral from puppy poop. It has a unique safety pin stain, is gram neg., and is cold resistant. You can treat it with doxy or aminoglycosides

Question 16

Salmonellosis is another cause of bloody diarrhea and abdominal pain. However, the onset of illness occurs within ___ - ___ hours of exposure to the pathogen, as opposed to ___ - ___weeks’ incubation time for amebic colitis. In addition, the course is 3–5 days, not several weeks.

Answer 16

Salmonellosis is another cause of bloody diarrhea and abdominal pain. However, the onset of illness occurs within 48 hours of exposure to the pathogen, as opposed to 2–4 weeks’ incubation time for amebic colitis. In addition, the course is 3–5 days, not several weeks.

Question 17

_____ can be clinically similar to amebic colitis, as both involve diarrhea containing blood and mucus. However, onset of symptoms is abrupt, not gradual, and tenesmus (cramping and rectal pain) is a prominent feature of shigellosis, not amebic colitis.

Answer 17

Shigellosis can be clinically similar to amebic colitis, as both involve diarrhea containing blood and mucus. However, onset of symptoms is abrupt, not gradual, and tenesmus is a prominent feature of shigellosis, not amebic colitis.

Question 18

Ulcerative colitis could present with bloody stools. However, the diagnosis of ulcerative colitis is made by ____ evidence in the context of negative stool studies. If a patient’s stool is positive for a specific antigen supports the diagnosis of amebic colitis over ulcerative colitis.

Answer 18

Ulcerative colitis could present in the manner that the patient described. However, the diagnosis of ulcerative colitis is made by colonoscopic evidence in the context of negative stool studies. The fact that the patient’s stool was positive for a specific antigen supports the diagnosis of amebic colitis over ulcerative colitis.

Question 19

___ __ which causes __ ___ which manifests with diarrhea, abdominal pain, and weight loss, and is confirmed by detecting the organism or its antigen. It is common in tropical countries with poor sanitation.

Answer 19

Entamoeba histolytica causes amebic colitis, which manifests with diarrhea, abdominal pain, and weight loss, and is confirmed by detecting the organism or its antigen. It is common in tropical countries with poor sanitation.

Question 20

S. Pneumo causes MOPS.

What does this stand for?

Answer 20

Meningitis

Otitis media

Pneumonia

Sinusitis

Question 21

Streptococcus pyogenes, also known as group A streptococcus (GAS) based on its Lancefield grouping, is a gram-____, catalase-_____, ____-hemolytic coccus.

S. pyogenes (GAS) is the causative organism of “strep throat.”

Streptococcus pneumoniae is an ____-hemoloytic coccus, which is/is not associated with strep throat. It is associated with a variety of other infections such as pneumonia, otitis media, meningitis, sinusitis etc.

Answer 21

Streptococcus pyogenes, also known as group A streptococcus (GAS) based on its Lancefield grouping, is a gram-negative, catalase-negative, beta-hemolytic coccus.

S. pyogenes (GAS) is the causative organism of “strep throat.”

Streptococcus pneumoniae is an alpha-hemoloytic coccus, which is not associated with strep throat. It is associated with a variety of other infections such as pneumonia, otitis media, meningitis, sinusitis etc.

Question 22

An inflamed oropharynx, lymphadenopathy, and white exudates on enlarged tonsils are indicative of “strep throat,” caused by ___ ____. Note the inflammation of the oropharynx and the petechiae, or small red spots, on the soft palate in the vignette image. ____ protein is the major virulence factor of S. pyogenes. It inhibits the activation of the complement system and protects the organism from ____.

B lymphocytes are able to recognize this protein and produce antibodies that opsonize the bacterium and destroy it. These antibodies against M protein are able to aid in the opsonization and destruction of the microorganism by macrophages and neutrophils. It is believed that cross-reactivity of these anti-M protein antibodies with heart muscle is the basis of ___ ___.

Because the M-protein looks similar to proteins on the ___ ___, some patients have have ___ due to molecular mimicry (remember miter hat from sketchy)

Answer 22

An inflamed oropharynx, lymphadenopathy, and white exudates on enlarged tonsils are indicative of “strep throat,” caused by Streptococcus pyogenes. Note the inflammation of the oropharynx and the petechiae, or small red spots, on the soft palate in the vignette image. M protein is the major virulence factor of S. pyogenes. It inhibits the activation of the complement system and protects the organism from phagocytosis. B lymphocytes are able to recognize this protein and produce antibodies that opsonize the bacterium and destroy it. These antibodies against M protein are able to aid in the opsonization and destruction of the microorganism by macrophages and neutrophils. It is believed that cross-reactivity of these anti-M protein antibodies with heart muscle is the basis of rheumatic fever.

Because the M-protein looks similar to proteins on the mitral valve, some patients have have endocartitis due to molecular mimicry (remember miter hat from sketchy)

Question 23

The treatment of choice for strep throat includes penicillin or ____ (for penicillin-sensitive individuals).

Sulfonamides and tetracycline can/can not be used for group A β-hemolytic pharyngitis. Sulfonamides are useful in the treatment of urinary tract infections and __ ___and ____ prophylaxis.

Answer 23

The treatment of choice for strep throat includes penicillin or erythromycin(for penicillin-sensitive individuals).

Sulfonamides and tetracycline can/can not be used for group A β-hemolytic pharyngitis. Sulfonamides are useful in the treatment of urinary tract infections and T. Gondii (CD < 100) and P. Jirovecii (CD <200) prophylaxis.

Question 24

Mycobacterium, Brucella, Listeria, Salmonella, Legionella, Francisella, and Yersiniaare ___ intracellular organisms.

Answer 24

Mycobacterium, Brucella, Listeria, Salmonella, Legionella, Francisella, and Yersiniaare facultative intracellular organisms (remember, they can go in and out of the cage in the sketchies)

Question 25

Streptococcus pyogenes is an encapsulated organism, primarily from ____ acid. Other organisms with capsules include Streptococcus pneumoniae, Salmonella, and Klebsiella. Which patients are at risk? What is the mnemonic for encapsulated organisms?

Answer 25

Streptococcus pyogenes is an encapsulated organism, primarily from hyaluronic acid. Other organisms with capsules include Streptococcus pneumoniae, Salmonella, and Klebsiella. Asplenic patients are at risk SHiNE SKiS Strep. Pyogenes H. Influenza type B Neisseria E. Coli Group B Strep. Klebsiella Salmonella

Question 26

An inflamed oropharynx, lymphadenopathy, and enlarged tonsils with exudates are indicative of strep throat, caused by ___ \_\_\_. This organism's main virulence factor is the __ \_\_ which protects it from the host's immune system.

Answer 26

An inflamed oropharynx, lymphadenopathy, and enlarged tonsils with exudates are indicative of strep throat, caused by Streptococcus pyogenes. This organism's main virulence factor is the M protein, which protects it from the host's immune system.

Question 27

Parents bring their 10-day-old infant to the emergency department. He is febrile and appears lethargic and irritable. The infant is immediately worked up for sepsis, and the appropriate resuscitation is started. Laboratory culture of cerebrospinal fluid reveals growth of gram-positive bacilli, with β hemolysis on sheep blood agar. The microbiologist notes that the same organism may cause meningitis in an immunocompromised adult. What is the likely mode of pathogen transmission to the immunocompromised adult?

Answer 27

Parents bring their 10-day-old infant to the emergency department. He is febrile and appears lethargic and irritable. The infant is immediately worked up for sepsis, and the appropriate resuscitation is started. Laboratory culture of cerebrospinal fluid reveals growth of gram-positive bacilli, with β hemolysis on sheep blood agar. The microbiologist notes that the same organism may cause meningitis in an immunocompromised adult. What is the likely mode of pathogen transmission to the immunocompromised adult? --\> Ingestion of unpasteurized milk

Question 28

\_\_\_ \_\_, which causes meningitis in neonates and the immunocompromised, is commonly found in unpasteurized milk, soft cheeses, coleslaw, and packaged cold cuts.

Answer 28

Listeria monocytogenes, which causes meningitis in neonates and the immunocompromised, is commonly found in unpasteurized milk, soft cheeses, coleslaw, and packaged cold cuts.

Question 29

Poliovirus initially infects the ___ \_\_\_ of the intestine and the motor neurons. It is passed by the fecal-oral route and can manifest with a spectrum of severity. It has three main disease manifestations. (1) The first is manifestation of infection could be a mild illness in which a febrile viral illness develops. This is the most common form and simply resolves. This is quite common in infants in less-developed nations, where sanitation is poor. (2) The second manifestation is aseptic meningitis. In this case fever and meningismus can develop as the virus infects the meninges. Recovery is usually complete in 1 week. (3) The third is the most feared presentation (the one described in this vignette)—\_\_\_ \_\_\_. In these cases, a mild febrile illness resolves after initial infection with the virus. Subsequently, 5–10 days later the fever recurs, followed by meningismus, and then flaccid asymmetric \_\_\_\_. The flaccid ____ is a result of destruction of ___ \_\_\_ neurons in the ____ horn of the spinal cord. In general, there can be a wide range of paralyses, but more severe forms take place in older patients. Replication of poliovirus in motor neurons of the anterior horn of the spinal cord results in cell destruction, which leads to the neurologic sequelae of poliomyelitis.

Answer 29

Poliovirus initially infects the Peyer patches of the intestine and the motor neurons. It is passed by the fecal-oral route and can manifest with a spectrum of severity. It has three main disease manifestations. (1) The first is manifestation of infection could be a mild illness in which a febrile viral illness develops. This is the most common form and simply resolves. This is quite common in infants in less-developed nations, where sanitation is poor. (2) The second manifestation is aseptic meningitis. In this case fever and meningismus can develop as the virus infects the meninges. Recovery is usually complete in 1 week. (3) The third is the most feared presentation (the one described in this vignette)—paralytic poliomyelitis. In these cases, a mild febrile illness resolves after initial infection with the virus. Subsequently, 5–10 days later the fever recurs, followed by meningismus, and then flaccid asymmetric paralysis. The flaccid paralysis is a result of destruction of lower motor neurons in the anterior horn of the spinal cord. In general, there can be a wide range of paralyses, but more severe forms take place in older patients. ## Footnote Replication of poliovirus in motor neurons of the anterior horn of the spinal cord results in cell destruction, which leads to the neurologic sequelae of poliomyelitis. Image A shows normal anterior horn cells (neurons, large purple/dark pink polygonal cells in a background of lighter pink glial material). Image B shows neurons that have been destroyed by the virus and are now dying, evidenced by pyknotic changes whereby the cytoplasm of the neuron is shrunken and becomes a darker pink/eosinophilic color and there is edema/vacuolization around the neurons that have been destroyed; additionally, the axonal projections are shrunken/destroyed, impairing neuronal function

Question 30

Autoimmune peripheral demyelination is the underlying mechanism of ___ \_\_\_ syndrome. This is most commonly seen in patients with ascending paralysis and weakness of bilateral lower limbs following a gastrointestinal bacterial or viral infection. ____ is implicated in the pathogensis of ___ \_\_ syndrome. Rapidly ascending weakness is characteristic of ___ \_\_ symdrome, whereas ___ often manifests with slowly progressive, ____ paralysis.

Answer 30

Autoimmune peripheral demyelination is the underlying mechanism of Guillain-Barré syndrome (GBS). GBS is most commonly seen in patients with ascending paralysis and weakness of bilateral lower limbs following a gastrointestinal bacterial or viral infection. Campylobacter is implicated in the pathogensis of GBS. **Rapidly** ascending weakness is characteristic of **GBS,** whereas **polio** often manifests with **slowly** progressive, **asymmetrical** paralysis.

Question 31

Because polio is a lower motor neuron disease, ____ are lost in the affected limbs, and the limbs atrophy. Loss of neurons in the lateral funiculi (corticospinal tracts) would produce an ___ motor neuron syndrome, manifesting with a positive ____ sign and \_\_\_reflexive deep tendon reflexes.

Answer 31

Because this is a lower motor neuron disease, reflexes are lost in the affected limbs, and the limbs atrophy. Loss of neurons in the lateral funiculi (corticospinal tracts) would produce an upper motor neuron syndrome, manifesting with a positive Babinski sign and hyperreflexive deep tendon reflexes.

Question 32

What is the first line of treatment for enterococcus?

Answer 32

Ampicillin (can cause watery diarrhea)

Question 33

Gardenerella vaginalis causes a fishy odor, especially in the presence of a ___ (\_\_\_ test). Gardnerella are pleomorphic bacilli with variable response to ___ \_\_\_. Classic histo picture is __ cells, which are vaginal epithelial cells covered with adherent offending bacteria.

Answer 33

Gardenerella vaginalis causes a fishy odor, especially in the presence of a ___ (\_\_\_ test). Gardnerella are pleomorphic bacilli with variable response to ___ \_\_\_. Classic histo picture is __ cells, which are vaginal epithelial cells covered with adherent offending bacteria.

Question 34

A 23-year-old sexually active woman presents to her physician with a high temperature, purulent cervical discharge, and cervical motion tenderness. A Gram stain prepared from a swab of the discharge is shown in the image. Which of the following is true about the infectious organism? This clinical picture is consistent with ___ \_\_\_ \_\_\_\_. Of the bacteria that cause ___ \_\_\_ \_\_\_, Neisseria gonorrhoeae is most likely to cause high fever and ____ discharge. The Gram stain of the gram-negative diplococci in the vaginal discharge is diagnostic of gonococcal PID. N. gonorrhoeae has type 4 pili, which are used for attachment to host cells and are the primary virulence factor of this bacteria. A complication of PID includes tubo-ovarian abscess. Additionally, scarring of the fallopian tubes may cause ectopic pregnancy, infertility, and chronic pain.

Answer 34

A 23-year-old sexually active woman presents to her physician with a high temperature, purulent cervical discharge, and cervical motion tenderness. A Gram stain prepared from a swab of the discharge is shown in the image. Which of the following is true about the infectious organism? This clinical picture is consistent with PID. Of the bacteria that cause PID, Neisseria gonorrhoeae is most likely to cause high fever and purulent discharge. The Gram stain of the gram-negative diplococci in the vaginal discharge is diagnostic of gonococcal PID. N. gonorrhoeae has type 4 pili, which are used for attachment to host cells and are the primary virulence factor of this bacteria. A complication of PID includes tubo-ovarian abscess. Additionally, scarring of the fallopian tubes may cause ectopic pregnancy, infertility, and chronic pain.

Question 35

The classic vignette of fever in the setting of peritoneal dialysis with erythema around the catheter site suggests an infection likely involving bacteria normally present on the skin. ___ \_\_\_ is part of the normal human skin flora and can cause systemic infection through entry sites into the body. These sites include those for Foley urine catheters, intravenous lines, prosthetic devices, and peritoneal dialysis catheters. ___ \_\_\_ can migrate along the tubing from the skin to the inside of the body with the help of ____ creation. Fevers, chills, diffuse abdominal tenderness, and rebound tenderness all suggest a diagnosis of peritonitis, which can be caused by\_\_\_ \_\_\_. ___ \_\_\_ is also a common cause of ___ with prosthetic valves.

Answer 35

The classic vignette of fever in the setting of peritoneal dialysis with erythema around the catheter site suggests an infection likely involving bacteria normally present on the skin. Staphylococcus epidermidis is part of the normal human skin flora and can cause systemic infection through entry sites into the body. These sites include those for Foley urine catheters, intravenous lines, prosthetic devices, and peritoneal dialysis catheters. S. epidermidis can migrate along the tubing from the skin to the inside of the body with the help of biofilm creation. Fevers, chills, diffuse abdominal tenderness, and rebound tenderness all suggest a diagnosis of peritonitis, which can be caused by S. epidermidis. S. epidermidis is also a common cause of endocarditis with prosthetic valves.

Question 36

\_\_\_ ____ is implicated in aspiration pneumonia, which manifests with cough productive of thick red sputum in a patient at high risk for aspiration, as with alcoholism and altered mental status.

Answer 36

Klebsiella pneumoniae is implicated in aspiration pneumonia, which manifests with cough productive of thick red sputum in a patient at high risk for aspiration, as with alcoholism and altered mental status.

Question 37

\_\_\_ ____ a gram negative, obligate anaerobic bacilli, is a normal member of the gastrointestinal flora. It can cause disease when trauma or surgery leads to perforation of the bowel wall. Although it is a common cause of peritoneal infections, it is not associated with catheter-associated peritonitis.

Answer 37

Bacteroides Fragilis. a gram negative, obligate anaerobic bacilli, is a normal member of the gastrointestinal flora. It can cause disease when trauma or surgery leads to perforation of the bowel wall. Although it is a common cause of peritoneal infections, it is not associated with catheter-associated peritonitis.

Question 38

Patients with ___ \_\_\_\_are at increased risk for bronchiectasis. Recurrent pulmonary infection in a patient with a family history of infertility among male members is highly suggestive of __ \_\_\_. Primary ciliary dyskinesia patients also suffer from infertility and recurrent pulmonary infections, but they often also present with situs inversus (which this patient does not have). Because of an impaired ability to clear mucous secretions from the airways, patients with __ \_\_\_ are especially prone to bacterial infection. ___ \_\_\_ is the most common cause of pneumonia in CF patients under 20 years of age, while ___ \_\_\_ is most common cause for those over 20 years of age. Infection with these organisms produces obstruction and dilation of the bronchi, resulting in \_\_\_\_\_. Prophylaxis against these infections includes antipseudomonal antibiotics and inhaled acetylcysteine, which breaks up mucous plugs. Signs and symptoms of bronchiectasis include halitosis, bloody sputum, and a productive cough. Abscess formation in the lung parenchyma is a serious condition, because it can cause hypoxia, fever, and sepsis. Patients at an increased risk for aspiration pneumonia are also at an increased risk for a lung abscess. Patients with cystic fibrosis are generally not predisposed to lung abscess formation, however. The most common pathogen in lung abscesses is Staphylococcus aureus, although these bacteria tend to be polymicrobial, with anaerobes often further complicating the pneumonia picture.

Answer 38

Patients with CF are at increased risk for bronchiectasis. Recurrent pulmonary infection in a patient with a family history of infertility among male members is highly suggestive of CF. Primary ciliary dyskinesia patients also suffer from infertility and recurrent pulmonary infections, but they often also present with situs inversus (which this patient does not have). Because of an impaired ability to clear mucous secretions from the airways, patients with CF are especially prone to bacterial infection. S. Aureus is the most common cause of pneumonia in CF patients under 20 years of age, while P. Auriginosa is most common cause for those over 20 years of age. Infection with these organisms produces obstruction and dilation of the bronchi, resulting in bronchoectasis Prophylaxis against these infections includes antipseudomonal antibiotics and inhaled acetylcysteine, which breaks up mucous plugs. Signs and symptoms of bronchiectasis include halitosis, bloody sputum, and a productive cough. Abscess formation in the lung parenchyma is a serious condition, because it can cause hypoxia, fever, and sepsis. Patients at an increased risk for aspiration pneumonia are also at an increased risk for a lung abscess. Patients with cystic fibrosis are generally not predisposed to lung abscess formation, however. The most common pathogen in lung abscesses is Staphylococcus aureus, although these bacteria tend to be polymicrobial, with anaerobes often further complicating the pneumonia picture.

Question 39

A 78-year-old HIV-positive man presents to his physician complaining of a new "bruise" on his left forearm that is progressively enlarging. Inspection of the area reveals multiple purple macules and papules that are firm to palpation. The lesion was biopsied and histologic examination revealed a predominance of endothelioid spindle cells often infiltrated with capillaries and extravasated erythrocytes. What is your diagnosis?

Answer 39

Kaposi's Sarcoma The patient is suffering from Kaposi sarcoma (KS), a malignant proliferation of lymphatic endothelium that often manifests with multifocal purple, brown, or black cutaneous lesions characterized as papular, macular, or nodular. The lesions are generally firm to palpation. The histologic picture of KS is notable for a predominance of endothelioid spindle cells, often infiltrated with capillaries and extravasated erythrocytes. KS is caused by the double-stranded DNA human herpesvirus (HHV) 8. KS is considered an AIDS-defining illness. Of the answer choices, only roseola infantum is caused by another member of the human herpesvirus family, HHV-6. Other members of the herpesvirus family are: herpes simplex virus (HSV)-1 and HSV-2 (oral and genital lesions), Epstein-Barr virus (mononucleosis and Burkitt lymphoma), cytomegalovirus (mononucleosis), and varicella-zoster virus (chickenpox and shingles).

Question 40

Kaposi sarcoma is an AIDS-defining illness caused by\_\_\_. Other members of the herpesvirus family are HSV-1 and HSV-2, varicella-zoster virus, Epstein-Barr virus, cytomegalovirus, and HHV-6. It is important to know the disease associated with all of the herpesviruses for Step 1 and clinical practice.

Answer 40

Kaposi sarcoma is an AIDS-defining illness caused by HHV-8. Other members of the herpesvirus family are HSV-1 and HSV-2, varicella-zoster virus, Epstein-Barr virus, cytomegalovirus, and HHV-6. It is important to know the disease associated with all of the herpesviruses for Step 1 and clinical practice.

Question 41

A 53-year old woman presents with hematuria and flank pain. She has a history of recurring urinary tract infections. The X-ray image obtained is shown here. What does she have?

Answer 41

Staghorn calculus in kidney - caused by proteus mirabellis