The objective of this practice guideline is to provide recommendations for the accurate diagnosis and optimal treatment of group A streptococcal pharyngitis in children and adults. The desired outcomes are prevention of acute rheumatic fever, prevention of suppurative complications, improvement of clinical symptoms and signs, reduction in transmission of group A β-hemolytic streptococci to close contacts of patients, and minimization of potential adverse effects of inappropriate antimicrobial therapy. This statement is an update of the practice guideline published in 1997 [1] and takes into account relevant research published since that time. A major substantive change is the acceptance of negative results of rapid antigen detection testing (RADT) for exclusion of acute streptococcal pharyngitis, without the previously mandated confirmation with a negative culture result, provided certain criteria are met, as detailed below. Diagnosis. Acute pharyngitis is one of the most frequent illnesses for which pediatricians, internists, and other primary care physicians are consulted. Although the group A streptococcus is the most common bacterial cause of acute pharyngitis, only a small percentage of patients with this condition are infected by group A streptococci. Moreover, group A streptococcal pharyngitis is the only commonly occurring form of acute pharyngitis for which antibiotic therapy is definitely indicated. Therefore, for a patient with acute pharyngitis, the clinical decision that usually needs to be made is whether the pharyngitis is attributable to group A streptococci. The signs and symptoms of group A streptococcal and other (most frequently viral) pharyngitides overlap broadly. Therefore, unless the physician is able with confidence to exclude the diagnosis of streptococcal pharyngitis on epidemiological and clinical grounds, a laboratory test should be done to determine whether group A streptococci are present in the pharynx. The test may be either culture of a throat swab specimen or an RADT, which detects the presence of group A streptococcal carbohydrate on a throat swab. A positive result of throat culture or RADT for a patient with signs and symptoms of acute pharyngitis is considered, for clinical purposes, to establish the diagnosis of "strep throat". However, because some RADTs appear to be considerably less sensitive than is culture of a throat swab specimen, a negative RADT result for a child or adolescent should be confirmed by performance of a throat culture, unless the physician has ascertained in his or her practice that the RADT being used is comparable in sensitivity to a throat culture. Because of the epidemiological features of acute pharyngitis in adults (e.g., low incidence of streptococcal infection and extremely low risk of rheumatic fever), diagnosis of this infection in adults on the basis of the results of an RADT, without confirmation of negative RADT results by negative results of culture, is an acceptable alternative to diagnosis on the basis of throat culture results (figure 1). The generally high specificity of RADTs should minimize over-prescription of antimicrobials for treatment of adults. Therapy. Patients with acute streptococcal pharyngitis should receive therapy with an antimicrobial agent in a dose and for a duration that is likely to eradicate the infecting organism from the pharynx. A number of antibiotics have been shown to be effective in treating group A streptococcal pharyngitis. These include penicillin and its congeners (such as ampicillin, amoxicillin, and the semisynthetic penicillins), as well as numerous cephalosporins and macrolides and clindamycin. Penicillin, however, remains the agent of choice because of its proven efficacy, safety, narrow spectrum, and its low cost. Amoxicillin is often used in place of oral penicillin V to treat young children; the efficacy appears to be equal. This choice is primarily related to acceptance of the taste of the suspension. Preliminary investigations have demonstrated that once-daily amoxicillin therapy is effective in the treatment of group A β-hemolytic streptococcal pharyngitis [2, 3]. If these results are confirmed by additional investigations, once-daily amoxicillin therapy, because of its low cost and relatively narrow spectrum, could become an alternative regimen to treat group A β-hemolytic streptococcal pharyngitis. Intramuscular administration of benzathine penicillin G is preferred for patients who are unlikely to complete a full 10-day course of oral therapy. Erythromycin is a suitable alternative for patients allergic to penicillin. First-generation cephalosporins are also acceptable for patients who do not exhibit immediate-type hypersensitivity to β-lactam antibiotics. Most oral antibiotic therapy must be administered for the conventional 10 days to achieve maximal rates of pharyngeal eradication of group A streptococci, but certain newer agents have been reported to achieve comparable rates of bacteriologic and clinical cure of streptococcal pharyngitis when administered for ≤5 days. However, no definitive results from comprehensive studies are available to allow final evaluation of these proposed shorter courses of oral antibiotic therapy [4], which, therefore, cannot be recommended at this time. Moreover, these antibiotics have a much broader spectrum than does penicillin, and most, even when administered for short courses, are more expensive. Except under special circumstances, neither repeat bacteriologic testing (culture or RADT) of patients who are asymptomatic after a course of antimicrobial therapy nor routine testing of asymptomatic household contacts of a patient with group A streptococcal pharyngitis is recommended. A small percentage of patients will have a recurrence of acute pharyngitis associated with results of throat culture or RADT that are positive for group A streptococci within a short time after completion of a course of antimicrobial therapy. Such episodes may be treated with an antimicrobial agent appropriate for treatment of the initial illness. If the previous treatment was with an oral agent and compliance is in question, a second course of intramuscular benzathine penicillin G therapy should be considered. When multiple episodes occur over the course of months or years, it may be difficult to differentiate viral pharyngitis in a Streptococcus carrier from true group A streptococcal pharyngitis. Therapy with certain antimicrobial agents, such as clindamycin and amoxicillin-clavulanate, may be beneficial, because they have been shown to yield high rates of eradication of streptococci from the pharynx under these particular circumstances. © 2002 by the Infectious Diseases Society of America.
