Role of the Microbiology Laboratory in Diagnosis and Management of Pharyngitis

The microbiology laboratory plays a very important role in the diagnosis and management of patients with pharyngitis. Arguably, it is at least as important in identifying the 70 to 80% of patients with pharyngitis who do no require antimicrobial therapy as it is in identifying patients for whom antimicrobial therapy is appropriate. One of our educational responsibilities is to inform clinicians of the importance of performing diagnostic testing to establish an accurate diagnosis. Although some guidelines now suggest that clinical criteria alone may suffice for the diagnosis of GAS infection in adults (20), this topic remains controversial. Bisno et al. (4) have stated that these new recommendations should have been tested in a clinical trial before being published. Laboratorians need to be strong advocates for both appropriate testing and judicial use of antimicrobial agents for diagnosis and management of pharyngitis. Antibiotic therapy is generally only indicated for pharyngitis caused by GAS (2, 9, 39) and the rare case caused by C. diphtheriae and N. gonorrhoeae. Additional study is needed to clarify the benefit, if any, for the diagnosis and treatment of for beta-hemolytic streptococci other than GAS. As noted by Bisno (3), the benefits of antimicrobial therapy against these organisms are currently unknown.