Orofacial Infections

Question 1

What is the source of the bacteria that cause the most odontogenic infections,
and what is the incidence of these infections?

Answer 1

Odontogenic infections are caused mostly by indigenous bacteria that normally live on or in the host.
When such bacteria gain access to deeper tissues, typically in the majority of cases through decayed
or nonvital teeth, they cause odontogenic infection.

Question 2

Which staphylococci are clinically important to orofacial infections?

Answer 2

Of the 23 species of staphylococci, only three are clinically important to orofacial infections: Staphylococcus aureus, Staphylococcus epidermidis, and Staphylococcus saprophyticus.

Question 3

What is Gram staining? What is its clinical significance?

Answer 3

Each specimen obtained from a patient with an infectious process initially should be stained according
to the protocol developed by Hans Christian Joachim Gram. The process involves staining, decolorizing, and re-staining the specimen with a different stain. The organisms are categorized into one of
four groups based on their stain retention and morphology: gram-positive cocci, gram-negative cocci,
gram-negative rods, or gram-positive rods. Because Gram staining can be completed within a few
minutes, it usually narrows the list of likely causative organisms immediately, whereas culture and
sensitivity testing and biochemical identification may take 1 to 5 days to complete. After the staining
process, organisms that retained their initial stain will remain violet (gram-positive), whereas those
that lost the initial stain will be re-stained red (gram-negative).

Question 4

What is the pattern of progression of odontogenic infections?

Answer 4

Early infection is often initiated by high-virulence aerobic organisms (commonly streptococci), which
cause cellulitis, followed by mixed aerobic and anaerobic infections. As the infections become more
chronic (abscess stage), the anaerobic bacteria predominate, and eventually the infections become
exclusively anaerobic.

Question 5

What is cellulitis?

Answer 5

Cellulitis is a warm, diffuse, erythematous, indurated, and painful swelling of the tissue in an infected
area. Cellulitis can be easy to treat but can also be severe and life threatening. Antibiotics and removal
of the cause are usually sufficient. Surgical incision and drainage are indicated if no improvement is
seen in 2 to 3 days, or if evidence of purulent collection is identified.

Question 6

What is an abscess?

Answer 6

An abscess is a pocket of tissue containing necrotic tissue, bacterial colonies, and dead white cells.
The area of infection may or may not be fluctuant. The patient is often febrile at this stage. Cellulitis,
which may be associated with abscess formation, is often caused by anaerobic bacteria.

Question 7

What are the signs and symptoms of a serious orofacial infection?

Answer 7

Serious infection occurs when the infection extends beyond the local area of infection and presents
life-threatening systemic manifestations, including airway compromise, bacteremia, septicemia, fever,
lethargy, fatigue, malaise, and dehydration. Swelling, induration, fluctuation, trismus, rapidly progressing infection, involvement of secondary spaces, dysphagia, odynophagia, and drooling are also signs
and symptoms of serious orofacial infection.

Question 8

What are the primary fascial spaces?

Answer 8

The primary spaces are the spaces directly adjacent to the origin of the odontogenic infections.
Infections spread from the origin of the infection into these spaces, which are:
• Buccal
• Submandibular
• Canine
• Submental
• Sublingual
• Vestibular

Question 9

What are the secondary fascial spaces?

Answer 9

Fascial spaces that become involved following spread of infection to the primary spaces (Fig. 28-2).
The secondary spaces are:
• Pterygomandibular
• Superficial and deep temporal
• Infratemporal
• Retropharyngeal
• Masseteric
• Masticator
• Lateral pharyngeal
• Prevertebral

Question 10

What imaging and laboratory studies are used for diagnosis of odontogenic
infections?

Answer 10

• Radiographs are used to identify the cause of infection: periapical, occlusal, and panoramic
views.
• Imaging studies are used to identify the extent of infection and presence of purulent collection. The
gold standard is computed tomography (CT) with contrast. In some instances, magnetic resonance
imaging (MRI), soft tissue films, and ultrasound can be useful.
• Lab studies are used to evaluate the immune system, white cell and differential counts, and culture
and sensitivity from the infection site.

Question 11

What are the principles of therapy for odontogenic infection?

Answer 11

The important components in treatment of odontogenic infection are:
• Determining the severity of infection
• Determining whether the infection is at the cellulitis or abscess stage
• Evaluating the state of the patient’s host defense mechanisms
Odontogenic infection is treated surgically, pharmacologically, or by medical support of the patient,
including removing the source of infection; incision and drainage; and use of antibiotics, fluids, analgesics, and nutritional support.

Question 12

How is the severity of odontogenic infection determined?

Answer 12

By analyzing the history, physical findings, and results of lab and imaging studies.

Question 13

What are the different methods of drainage of odontogenic infections?

Answer 13

• Endodontic treatment
• Extraction of the offending tooth
• Incision and drainage of soft tissue collection

Question 14

What are the surgical principles of incision and drainage?

Answer 14

• Before incision, obtain fluid for culture through aspiration of pus using a syringe and needle.
• Incise the abscess in healthy skin or mucosa and in a cosmetically or functionally acceptable place,
using blunt dissection and thorough exploration of the involved space.
• Use one-way drains in intraoral abscesses; use through-and-through drainage in extraoral cases.
• Remove the drain gradually from deep sites.

Question 15

What should be reevaluated during the follow-up appointment after treating a
patient for odontogenic infection?

Answer 15

• Response to treatment (subjective improvement of pain and other subjective symptoms)
• Toxicity reactions to antibiotics
• Recurrence of infection
• Secondary infection (e.g., Candida)
• Presence of allergic reactions

Question 16

What are the principles of antibiotic use?
When choosing a specific antibiotic as part of treatment of odontogenic infection, adhere to the following principles:

Answer 16

• Use the correct and narrow-spectrum antibiotic.
• Use the least toxic drug with the fewest side effects.
• Use bactericidal drugs whenever possible.
• Be aware of drug cost.
• Ensure effective oral administration through the use of proper dose and proper dosage
interval.
• Continue the antibiotic for an adequate length of time.
• Administer
the antibiotics through the proper route.

Question 17

What is the beta-lactam group of antibiotics?

Answer 17

These antibiotics, which have in common a beta-lactam ring in their structures, comprise three classes:
penicillins, cephalosporins, and carbapenems. Penicillins and cephalosporins encompass many different
antibiotics that are commonly used for odontogenic infection. Imipenem is an example of the carbapenems.

Question 18

What was the first carbapenem to be used clinically?

Answer 18

Imipenem was the first clinically available carbapenem. It has the broadest antibacterial activity of any
currently used systemic antibiotic and, therefore, is reserved for use in treatment of severe head and
neck infections.

Question 19

What is the mode of action of penicillin?

Answer 19

Penicillin affects bacteria by two mechanisms:
1. It inhibits bacterial cell wall synthesis.
2. It activates endogenous bacterial autolytic processes that cause cell lysis. The bacteria must be
actively dividing, and the cell wall must contain peptidoglycans for this action. Penicillin inhibits
enzymes necessary for cell wall synthesis.

Question 20

How do bacteria build up resistance to antibiotics?

Answer 20

An antibiotic’s ability to penetrate cell walls and bind to enzymes plays an essential role in resistance
of antibiotics. Specifically, bacteria build resistance by two mechanisms:
1. Alteration in cell wall permeability to prevent antibiotics from inhibiting peptidoglycan synthesis
2. Bacterial production of beta-lactamase that causes beta-lactams to become ineffective

Question 21

When should antibiotics be used?

Answer 21

• Acute-onset
infection
• Involvement of fascial spaces
• Diagnosed osteomyelitis of the jaw
• Patients with compromised host defences
• Infection with diffuse swelling
• Severe pericoronitis

Question 22

When are prophylactic antibiotics for prevention of odontogenic infections not
necessary?

Answer 22

Antibiotics have minimal or no benefits in the treatment of chronic well-localized abscess, minor
vestibular abscess, dry socket, and root canal sterilization.

Question 23

What are the indications for prophylactic antibiotics?

Answer 23

• To prevent local wound infection
• To prevent infection at the surgical site causing local wound infection
• To prevent metastatic infection at a distant susceptible site due to hematogenous bacterial seeding
from the oral flora (e.g., subacute bacterial endocarditis, prosthetic joint replacement) following oral
surgical procedures

Question 24

When are prophylactic antibiotics indicated for prevention of local wound infection?

Answer 24

• When the procedure to be performed has a high incidence of infection
• When infections may have grave consequences
• When the patient’s immune system is compromised
• When the surgical procedure lasts longer than 3 hours
• When the surgical procedure has a high degree of contamination

Question 25

What is the antibiotic of choice for treatment of odontogenic infection?

Answer 25

The empiric therapy is penicillin or penicillin plus metronidazole, if the patient is not allergic to antibiotics and is not immunocompromised. In patients who are allergic to penicillin, clindamycin is an excellent alternative. Definitive antibiotic therapy should be based on culture and sensitivity.

Question 26

What is the antibiotic of choice for treatment of odontogenic infection?

Answer 26

The empiric therapy is penicillin or penicillin plus metronidazole, if the patient is not allergic to antibiotics and is not immunocompromised. In patients who are allergic to penicillin, clindamycin is an excellent alternative. Definitive antibiotic therapy should be based on culture and sensitivity.

Question 27

What are the possible causes of failure of antibiotic therapy?

Answer 27

• Inadequate surgical treatment • Depressed host defences • Presence of foreign body • Problems associated with use of antibiotics (e.g., patient compliance, inadequate dose, antibioticrelated infection, use of wrong antibiotic)

Question 28

Which cranial nerves pass through the cavernous sinus?

Answer 28

Cranial nerves III, IV, V (ophthalmic division of V), and VI pass through the cavernous sinus.

Question 29

What is cavernous sinus thrombosis?

Answer 29

It is an uncommon but potentially lethal extension of odontogenic infection. Valveless veins in the head and neck allow retrograde flow of the infection from the face to the sinus. The pterygoid plexus of veins and angular and ophthalmic veins may contribute to retrograde flow. The first clinical signs of cavernous sinus thrombosis include vascular congestion in periorbital, scleral, and retinal veins. Other clinical signs include periorbital edema, proptosis, thrombosis of the retinal vein, ptosis, dilated pupils, absent corneal reflex, and supraorbital sensory deficits.

Question 30

What are the pathways of odontogenic infection to the cavernous sinus?

Answer 30

An orofacial infection can reach the cavernous sinus through two routes: an anterior route via the angular and inferior ophthalmic veins, and a posterior route via the transverse facial vein and the pterygoid plexus of veins.

Question 31

What is the treatment for maxillary sinus infections?

Answer 31

Treatment for maxillary sinus is based on a combined approach of medical treatment and, if necessary, surgical treatment. The medical treatment includes use of antibiotics, topical or oral decongestants, antihistamines, and topical or oral steroids. Commonly prescribed antibiotics for the treatment of maxillary sinusitis include ampicillin, amoxicillin, amoxicillin plus clavulanic acid, cefaclor, cefuroxime axetil, and trimethoprim-sulfamethoxazole. Surgical treatment is indicated when the underlying cause of the infection cannot be corrected with medical therapy. The goal is to reestablish drainage and remove the underlying cause (if identified) using minimally invasive techniques, such as functional endoscopic surgery.

Question 32

What are the most common bacterial and fungal infections affecting patients with diabetes mellitus?

Answer 32

Mucormycosis (phycomycosis) is the most common infection in patients with diabetes mellitus, especially those with diabetic ketoacidosis. Of patients with rhinocerebral mucormycosis, 75% have ketoacidosis. Mucormycosis is a fungal disease, possibly caused by phycomycetes organisms of the Zygomycetes class.

Question 33

What is the treatment for animal and human bites?

Answer 33

Treatment includes antibiotic therapy and surgical intervention. Good surgical technique involves debridement of the devitalized tissue and thorough irrigation with copious quantities of saline. Oral ampicillin and amoxicillin are the antibiotics of choice for both types of bites. Also provide prophylaxis against rabies virus, if deemed necessary.

Question 34

Which diseases are associated with Epstein-Barr virus?

Answer 34

Mononucleosis, Burkitt’s lymphoma, nasopharyngeal carcinoma, and hairy leukoplakia are associated with the Epstein-Barr virus.

Question 35

What are the common antifungal agents?

Answer 35

The most common antifungal agents are nystatin, clotrimazole, ketoconazole, and amphotericin B.

Question 36

What are the common antiviral agents?

Answer 36

The common antiviral agents are acyclovir, zidovudine, vidarabine (ara-A), and idoxuridine.

Question 37

Is the following statement true or false? Osteomyelitis can be classified into three major groups.

Answer 37

False. Osteomyelitis is generally classified as two major groups: suppurative and nonsuppurative.

Question 38

What is the most common classification of osteomyelitis of the jaws?

Answer 38

Suppurative osteomyelitis is classified as acute, chronic, or infantile osteomyelitis. Nonsuppurative osteomyelitis is classified as chronic sclerosing (focal and diffuse), Garré’s sclerosing osteomyelitis, and actinomycotic osteomyelitis.

Question 39

What is Garré’s osteomyelitis?

Answer 39

Garré’s osteomyelitis is characterized by localized, hard, nontender, bony swelling of the lateral and inferior aspects of the mandible. It is primarily present in children and young adults and is usually associated with carious molar and low-grade infection. The radiographic features of Garré’s osteomyelitis include a focal area with proliferative periosteal formation, most often seen as a carious mandibular molar opposite the hard bony mass, and periosteal bony outgrowth seen on occlusal films. Treatment of this condition includes extraction of the tooth and removal of potential sources, which leads to gradual remodeling of the area involved. Long-term postoperative antibiotics generally are not necessary

Question 40

What are the general treatment principles of osteomyelitis of the jaws?

Answer 40

Treatment of osteomyelitis of the jaws usually includes both surgical intervention and medical management of the patient, as well as sensitivity testing. Medical management involves administration of empirical antibiotics, performing Gram stain, administration of culture-guided antibiotics, use of appropriate imaging to rule out other causes such as tumors, and evaluation and correction of the patient’s immune defenses. Surgical treatment includes removal of loose teeth and foreign bodies; sequestrectomy; debridement; decortication; resection; and reconstruction, if necessary.

Question 41

How does the management of severe odontogenic infections in pregnant patients differ from that in normal patients?

Answer 41

The principles of treatment of odontogenic infections in pregnant patients are the same and include removal of the source of infection, incision and drainage, antibiotic therapy and medical support. However, the physiologic changes associated with pregnancy as well as the status of the fetus have to be carefully considered and make medical, surgical, and anesthetic management of these infections in the pregnant patient very challenging. Although the details of physiologic changes associated with pregnancy have been discussed elsewhere, it is worth emphasizing that when treating these patients,such physiologic changes can impact the outcome of the infection treatment as well as the viability of the fetus. Such changes include: • Cardiovascular: changes in blood pressure, cardiac output, heart rate, etc. • Respiratory: changes in respiratory drive, tidal volume, respiratory rate, and minute ventilation • Endocrine: increased incidence of gestational diabetes • Urinary: changes in kidney output and risk of urinary tract infections • Hepatic function: changes in serum alkaline phosphate, bilirubin, and peripheral edema • Hematological: increases in erythrocyte and leukocyte counts and increases in plasma volume with resulting hypercoagulability

Question 42

What is the drug of choice for the treatment of an abscess?*

Answer 42

A knife. Surgically drain the abscess. Abscesses have no circulation of blood within them to deliver an antibiotic. The antibiotic, even if injected directly into the abscess, would be worthless because the abscess contains a soup of dead microorganisms and white blood cells (WBCs). Even if the organisms were barely alive, they would not be reproducing and incorporating the antibiotic. The drug most likely would not work at all at the pH and pKa conditions of the abscess environment. If there is an indication for an antibiotic, it would be in the circulation around the compressed inflammatory edge of the abscess and the cellulitis (at the vascularized “peel of the orange”) and uncontaminated tissue planes through which the necessary drainage must be carried out. A focal infection is managed by a local treatment, which is both necessary in all abscesses and sufficient treatment in many. Adjunctive systemic antibiotics are occasionally indicated for protection of the tissues through which drainage is carried out. If it helps to make this fundamental surgical principle clear, here is the rule of thumb for management of abscesses: Where there is pus, let there be steel. Perhaps one of the most gratifying procedures in all of medicine is the drainage of pus with immediate relief of local and systemic symptoms (e.g., a perirectal abscess).

Question 43

What can the patient do to help decrease surgical wound infection?*

Answer 43

Stop smoking. Although obesity, poor nutritional status, advanced age, and diabetes are risk factors for SSIs, cigarette smoking is probably the leading preventable patient factor for SSIs, just like it is the leading preventable cause of death and disability in the United States. Half of all people who smoke eventually die from a smoking-related illness. Smoking not only kills, but also more than triples the risk of incisional wound breakdown; in one study, smoking increased the incidence of SSIs in clean operative procedures sixfold, from 0.6% to 3.6%. Tobacco use results in decreased blood flow and decreased oxygen delivery to the wound. Toxic tobacco by-products also directly impede all stages of wound healing. Despite this knowledge, surgeons continue to operate electively on smokers, and most smokers continue to smoke up until the day of surgery.