This article focuses on the antimicrobial therapy of head and neck infections from odontogenic origin. Odontogenic infections are among the most common infections of the oral cavity. They are sourced primarily from dental caries and periodontal disease (gingivitis and periodontitis). Many odontogenic infections are self-limiting and may drain spontaneously. However, these infections may drain into the anatomic spaces adjacent to the oral cavity and spread along the contiguous facial planes, leading to more serious infections. Antibiotics are an important aspect of care of the patient with an acute odontogenic infection. Antibiotics are not a substitute for definitive surgical management.
Key points
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Odontogenic infections have many presentations and contribute primarily to health disorders seen in both inpatient and outpatient settings across the United States and worldwide.
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There are varying antimicrobial therapies that can be used for patients with odontogenic infections. Each case should be assessed in full before concluding the antibiotic of choice for the patient’s therapy; this is a continually evolving scenario that requires close follow-up with the possibility for change.
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Pharmacotherapy is an adjuvant therapy, not the definitive treatment for odontogenic infections.
Introduction
This article focuses on the antimicrobial therapy of head and neck infections from odontogenic origin. It will not discuss the antimicrobial treatment of uncomplicated dental caries and periodontal disease. This discussion is limited to adult immunocompetent patients; pediatrics, pregnant patients, patients with renal, hepatic, and cardiac problems are excluded, and management of these patients should be addressed on a case-by-case basis by the provider.
Odontogenic infections are among the most common infections of the oral cavity. They are sourced primarily from dental caries and periodontal disease (gingivitis and periodontitis). Many odontogenic infections are self-limiting and may drain spontaneously. However, these infections may drain into the anatomic spaces adjacent to the oral cavity and spread along the contiguous facial planes, leading to more serious infections. Holmes and Pellecchia divide facial infections by primary and secondary spaces. Primary spaces include buccal, canine, sublingual, submandibular, submental, and vestibular spaces. After a direct primary infection, secondary infection can take place. These spaces include pterygomandibular, infratemporal, masseteric, lateral pharyngeal, superficial, and deep temporal, masticator, and retropharyngeal.
Infections in the head and neck have an array of presentations. However, they most often demonstrate classic signs and symptoms of infection in the early stages, including inflammation, edema, redness, and pain (calor [heat], rubor [redness], dolor [pain], tumor [swelling]). As the infection persists, systemic symptoms may result, including more significant generalized or pronounced edema, trismus, tachycardia, dysphagia fever, fatigue, and malaise.
These infections pose many threats, including patient mortality. Primary concern of the disease is that of airway security. In the past, the major cause of mortality was due to airway obstruction. Modern treatment guidelines for early airway security and surgical intervention have reduced this airway-related mortality. A 2015 study by Bali and colleagues demonstrated that embarrassment of the airway was a tertiary cause of mortality accounting for only 5% of 18 deaths among 2790 patients. The 2 most common causes of mortalities in these patients were sepsis and preexisting organ failure. In addition, there are morbidities related to the course of spread to critical structures, which can include the orbit, brain, and spine. Risks of odontogenic infection also include progression to sepsis, bacteremia, endocarditis, and acute respiratory distress syndrome.
For the modern oral and maxillofacial surgeon or surgical trainee, these infections are commonly seen in an emergent setting, whether in office or in the local emergency department. In 2007, the Nationwide Emergency Department Sample database included 302,507 Emergency Department visits for facial cellulitis in the United States. These patient encounters led to a significant financial expense. Kim and colleagues showed many factors associated with increased length of stay in odontogenic infections with a mean cost of $24,290 per patient.
Abramowicz and colleagues explored the nationwide inpatient sample from 2012 and 2013 showing that facial cellulitis accounted for 74,480 hospitalizations. Demographic results from the study show a greater number of women than men and mean age of 47.5 years. In the retrospective analysis of the nationwide inpatient sample, 86.1% of the patients were routinely discharged and 0.2% of the patients died inthe hospital. Of note, this study did not distinguish between odontogenic and other causes of facial cellulitis. It is inferred that many of these infections are odontogenic in nature. Other sources for head and neck infections could include peritonsillar, intravenous (IV) drug abuse, and foreign bodies.
Microbiology of odontogenic infections
Odontogenic infections are usually attributed to the endogenous flora of the mouth and not the introduction of nonresident bacteria. It is important to emphasize that suppurative odontogenic infections are typically polymicrobial in nature, with mixed aerobic and anaerobic bacteria present. However, the anaerobes generally outnumber the aerobic bacteria by a factor of 3- to 4fold. ,
Knowledge of the usual microbial flora of the mouth and dental surfaces will help in the selection of empiric antimicrobial therapy while awaiting final culture results. In general, it is recommended to use antibiotics that cover these organisms, including anaerobic bacteria, as these may not necessarily grow with the usual available techniques or because of delays in getting samples to the microbiology laboratory. When “normal oropharyngeal flora” results are obtained from culture, practitioners should choose broad-spectrum antibiotics and not consider these results true negative cultures.
Actinomycosis is a rare subacute to chronic bacterial infection caused by Actinomyces spp, a bacterium that normally colonizes the human mouth. One of the common presentations includes cervicofacial actinomycosis. It is characterized by contiguous spread, suppurative and granulomatous inflammation, and formation of multiple abscesses and sinus tracts that may discharge sulfur granules. It is important to consider Actinomycosis in the differential diagnosis of orofacial and head and neck infections, as treatment with antimicrobial therapy is quite different from the treatment of other odontogenic infections. The preferred treatment for Actinomycosis is penicillin G 18 to 24 million units IV daily in divided doses for 2 to 6 weeks and then amoxicillin 500 to 750 mg orally 3 to 4 times a day for 6 to 12 months.
Diagnostics of odontogenic infections
Imaging
A careful history and physical examination are important in the diagnosis of odontogenic infections. Clinical symptoms, vital signs, microbiological evaluation, and diagnostic imaging are all crucial in identifying the cause of infection and to help guide the course of treatment.
Modern imaging techniques provide the surgeon excellent topography of the spreading infection, but not all active infections warrant computed tomography (CT) imaging for definitive treatment. , There are “red-flag” clinical symptoms to consider CT imaging and likely inpatient stay. These “red-flag” clinical symptoms include but are not limited to trismus, fever, dysphagia, odynophagia, pain, and dyspnea. , ,
Weyh and colleagues suggested “red-flag” clinical signs that warrant the use of CT imaging and include fever, pain, voice change, elevated floor of mouth, signs of inflammation of deep fascial spaces, periorbital edema, nonpalpable inferior border of the mandible, dyspnea, dysphagia or odynophagia, and trismus. The study found 56.6% of CT imaging was unnecessary. Christensen and colleagues performed a study that determined emergency medicine physicians conducted CT imaging on 61.7% of patients who did not require CT imaging by study standards. Recommendations were made to increase education to providers to avoid unnecessary imaging.
There is a wide array of clinical imaging that can be used to assess head and neck infections in the emergency setting, but the most common is CT imaging with IV contrast in a hospital setting and cone beam CT or panoramic film if the patient is being evaluated in an outpatient clinic. CT is particularly sensitive for soft tissue with IV contrast and remains the imaging modality of choice for assessment of most odontogenic infections ( Fig. 1 ).
CT 3-dimensional imaging will show ring enhancing loculations of well-formed abscesses, gas formation or entrapment, and finally, the soft tissue edema associated with these infections. Using IV contrast-enhanced CT for emergency diagnosis of head and neck infections is currently routine because it is fast, readily available, and relatively inexpensive. , However, limited soft tissue contrast and artifacts from bone and dental implants may compromise accurate delineation of neck disease. 21
Although in-office panoramic imaging may be readily available, it is only beneficial in identifying a possible odontogenic source of the infection, as the soft tissue is not adequately visualized. Panoramic imaging can be reserved for an outpatient setting or should medical CT be unavailable.
In patients with persistent odontogenic infections that are not clearly diagnosed by CT imaging with IV contrast and/or MRI, nuclear medicine studies, such as triple-phase bone scan or indium-labeled scans, can be used especially in cases of osteomyelitis of the jaw, but they are not typically used because they can be difficult to interpret.
Microbiology
Obtaining appropriate material for culture and processing is important in the diagnosis of odontogenic infections. One of the difficulties in defining etiologic agents for odontogenic infections is the presence of normal resident flora. For closed space infections, it is very important that the normal oral flora be excluded during the specimen collection. Needle aspiration of loculated pus by an extraoral approach is desirable, and specimens should be transported immediately to the laboratory under anaerobic conditions. Figs. 2 and 3 show a clinical specimen of an odontogenic abscess.
Contamination by the resident oral flora is inevitable for intraoral infections. In this setting, direct microscopic examination of stained smears, such as Gram stain, often provides more useful information than culture results from surface swabs.
The gram-stain step is implemented to provide basic information about the culture sample and to provide some information to the clinician while awaiting culture results. If the sample shows excess epithelial cells, the laboratory can conclude that the sample was poorly obtained and includes skin or oral mucous membrane flora. If the presence of white blood cells is predominant, it can be assumed that the clinician gathered a good collection of purulent material.
Gram stains can also be helpful if they show a mixture of gram-positive and gram-negative bacteria and the aerobic culture is negative. This should raise the suspicion of anaerobic involvement. This information is useful especially if only aerobic cultures are sent.
Cultures will be specifically plated for both aerobic and anaerobic growth. The plates are monitored based on hospital protocol, with a minimum of daily evaluation. Aerobic growth assessment begins at 24 hours, and anaerobic growth assessment begins at 48 hours ( Fig. 4 ).
