The oral cavity is one of the initial areas examined when a patient presents with complaints of cough, cold, or sore throat. An understanding of the infectious processes affecting this area and how to diagnose them accurately is important. 17 Visits to physicians for symptomatic complaints related to possible infections of the oral cavity are a common occurrence. Not only is it important to accurately determine the entity causing an infectious syndrome so that appropriate therapy may be given, it is also important because these interactions with the healthcare system likely result in a large amount of unnecessary antibiotic prescribing. For example, a recent report by Mainous et al 41 found that 60% of over 2000 patients seeking medical care were given at least one of 19 different antimicrobial agents for acute nasopharyngitis (the common cold). Less than 2% had an accompanying bacterial sinusitis or otitis. Because the symptomatic complaints the authors described are nearly all secondary to viral infections, such antibiotic prescribing is not beneficial. Similarly, although chronic cough is often treated with antimicrobial agents, 90% is caused by smoking, postnasal drip, asthma, gastroesophageal reflux, and chronic bronchitis. 50 None of these latter conditions are usually responsive to antimicrobial therapy. Data collected in the United States between 1980 and 1994 for persons presenting with a complaint of cough found that antibiotic prescription rose from 59% of visits in 1980 to 70% in 1994. 44 Interestingly, clinical characteristics did not appear to be the major influence in such prescriptions. 44
Infections related to the oral cavity are important from two very different perspectives. First, when they occur within the oral cavity, the result frequently is significant morbidity (pain), such as with pharyngitis, stomatitis, and even dental caries. The intraoral infectious syndromes and their management are diverse. For example, dental caries is a major medical and economic problem, typically associated with infection by Streptococcus mutans 17 ; however, specific microbiologic evaluation is rarely done or needed for caries. Pharyngitis is also common, but only a very few inciting microbes require specific treatment. Other local infections, such as candidiasis (thrush), actinomycosis, and sexually transmitted diseases, occur less frequently, but all require therapy. Second, an infectious disease from mouth origin can present at a distant site, resulting in both morbidity and mortality. These range from sinusitis, where the connection to the oral cavity is direct, to infections like endocarditis, where oral microbes travel through the vascular system to reach their final site of infection.
The infectious diseases associated with the oral cavity have their own unique, often mixed, microbiology, making culture detection of a specific organism linked to a given episode of infection frequently complicated. Because infections in this area most often arise from normally resident flora, it is important to first understand what microbes are often found here. Nonhemolytic streptococci, coagulase-negative staphylococci, micrococci, Corynebacterium spp (aerobic diphtheroids), Neisseria spp (other than N. meningitidis or N. gonorrhoeae), spirochetes, Lactobacillus, and Veillonella spp are nonpathogenic organisms frequently present. Additionally, β-hemolytic streptococci, viridans streptococci, Peptostreptococcus spp, Streptococcus pneumoniae, Staphylococcus aureus, N. meningitidis, Corynebacterium diphtheriae, Mycoplasma spp, Haemophilus influenzae, Haemophilus parainfluenzae, Moraxella catarrhalis, Fusobacterium spp, Mycobacterium spp other than tuberculosis (MOTT), Enterobacteriaceae, Acinetobacter spp, Pseudomonas spp, Klebsiella ozaenae, Eikenella corrodens, Bacteroides spp, Actinomyces spp, herpes simplex virus (HSV), Candida albicans, filamentous fungi, and even Cryptococcus neoformans may be recovered from the oral cavity as pathogens or commensals. The best diagnostic approach is to begin with a careful history and physical examination, followed by specific laboratory testing, to detect the suspected pathogens. The purpose of this article is to highlight the likely pathogens responsible for oral cavity infections, and to suggest ways to integrate the clinical and laboratory diagnosis to establish an accurate microbiologic diagnosis for these infectious diseases.