Practice Guidelines for the Diagnosis and Management of Group A Streptococcal Pharyngitis

Abstract

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 overprescription of antimicrobials for treatment of adults. Diagnosis and management of acute pharyngitis. The algorithm applies to uncomplicated cases of acute pharyngitis. Additional diagnostic and therapeutic measures may be necessary for patients with suppurative complications (e.g., peritonsillar abscess or cervical lymphadenitis) or infection with uncommon pharyngeal bacterial pathogens (e.g., Corynebacterium diphtheriae, Neisseria gonorrhoeae) is suspected. *See the discussion in Diagnosis of Group A Streptococcal Pharyngitis. Neg., negative result; pos., positive result. 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 of patients who are a course of antimicrobial therapy testing of contacts of a patient with group A streptococcal pharyngitis is A small percentage of patients have a of acute pharyngitis with results of throat culture or RADT that are positive for group A streptococci a short of a course of antimicrobial therapy. may be with an antimicrobial agent for treatment of the If the treatment with an oral agent and is in a course of benzathine penicillin G therapy should be the course of or may be to pharyngitis in a from group A streptococcal pharyngitis. with certain antimicrobial as and may be because have been shown to high rates of eradication of streptococci from the under these Group A streptococcal pharyngitis is an acute infection of the that is by 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 in adults. The physician for a patient with acute pharyngitis must a diagnosis and determine which, should be clinical and laboratory evaluation result in a diagnosis of group A β-hemolytic streptococcal pharyngitis, penicillin remains the of choice for the patient allergic to penicillin, alternative antimicrobial agents are The desired outcomes are as prevention of acute rheumatic prevention of suppurative complications (e.g., peritonsillar cervical and improvement in clinical symptoms and rapid in to transmission of group A β-hemolytic streptococci to and other close contacts of the and to allow the rapid of and minimization of potential adverse effects of inappropriate antimicrobial therapy. A number of clinical of diagnostic and treatment for group A streptococcal pharyngitis The for of of for for of streptococcal to treatment from duration and of and recommendations and the of the and of the are by of an of 1). A of the of a and the the of the These are in of for recommendations in clinical of diagnostic a high on the diagnostic test with the in acute pharyngitis to group A β-hemolytic streptococci from that to other evaluation of high to proven clinical and bacteriologic efficacy, safety, spectrum of antimicrobial and cost. and Group A β-hemolytic streptococcus is the most common bacterial cause of acute pharyngitis diagnosis by antimicrobial therapy is for the the Although acute pharyngitis is one of the most frequent illnesses for which and other primary care physicians are only a relatively small percentage of patients with this condition are infected by group A streptococci. Moreover, the signs and symptoms of group A streptococcal and pharyngitis overlap that accurate diagnosis on clinical is usually the of by certain other pharyngeal bacterial pathogens (e.g., Corynebacterium and Neisseria antimicrobial therapy is of no proven as treatment for acute pharyngitis to other than group A streptococci. Therefore, is extremely that physicians exclude the diagnosis of group A streptococcal pharyngitis to inappropriate administration of antimicrobials to of patients with pharyngitis. only does therapy patients to the and of antimicrobial therapy, to the of which is being reported with in the and of acute pharyngitis. If the clinical of group A streptococcal pharyngitis is by of the organism in from the the should the most antimicrobial therapy, from a number of antimicrobial agents to be effective group A streptococci. Because the cost to the patient may as much as on the recommendations are on safety, and cost. are the most common cause of acute pharyngitis as and frequently cause acute pharyngitis. agents of acute pharyngitis include and is a frequent cause of acute pharyngitis that is often by the other clinical features of (e.g., and with and a number of other agents may be with acute pharyngitis. as and are uncommon of acute pharyngitis. Group A β-hemolytic streptococci are the most common cause of bacterial pharyngitis, but other also cause acute pharyngitis These include and G β-hemolytic streptococci and is a cause of acute pharyngitis that may be with a to that in cases of fever, in cause acute pharyngitis in and with other as and and with (e.g., are of acute pharyngitis. is from this of potential group A β-hemolytic 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 β-hemolytic streptococci. Acute group A β-hemolytic streptococcal pharyngitis has certain epidemiological and clinical features The is primarily a of children of in usually in the and Patients with group A β-hemolytic streptococcal pharyngitis commonly present with throat of on and and may also be in children patients have with or without and cervical may include a on the in and a However, of these is for group A β-hemolytic streptococcal pharyngitis. the of or the presence of clinical features as and a than a streptococcal and epidemiological and diagnosis of pharyngitis to group A β-hemolytic streptococci should be for group A β-hemolytic streptococcal whether to a test for a patient with acute pharyngitis, the clinical and epidemiological should be A of close with a of streptococcal pharyngitis is as is an of a high of group A β-hemolytic streptococcal in the usually not be done for patients with acute pharyngitis that has clinical and epidemiological features not of a group A streptococcal of diagnostic studies for group A β-hemolytic streptococci not only the of positive test results but also the percentage of cases in which patients have positive test results and are than have been made to the clinical and epidemiological features of acute pharyngitis into that to the that a is by group A β-hemolytic streptococci These clinical are in patients who are at low risk of streptococcal infection that performance of a throat culture or an RADT is usually However, the signs and symptoms of streptococcal and pharyngitis overlap for diagnosis to be made with the diagnostic on clinical The clinical diagnosis of group A β-hemolytic streptococcal pharyngitis cannot be made with even by the most and bacteriologic confirmation is in the diagnosis of acute pharyngitis in adults. Group A streptococci cause of cases of acute pharyngitis in patients but only of illnesses in adults However, the risk of acute pharyngitis to group A streptococci is for of children and adults into close with The risk of a of acute rheumatic is extremely low in even should have an and of streptococcal pharyngitis. Because of these epidemiological the of a clinical algorithm without confirmation has been recommended as an acceptable alternative basis for diagnosis of infection in adults this algorithm a positive result of group A streptococcal throat culture with an of on the number of clinical features present of this diagnostic result in treatment of an number of adults with that is an result in this which has a low of streptococcal pharyngitis and low risk of rheumatic or rheumatic However, because of the features of acute pharyngitis in exclusion of the diagnosis on the basis of negative RADT without confirmation by negative culture is an acceptable alternative to diagnosis on the basis of throat culture The generally high specificity of RADT should minimize overprescription of antimicrobials for treatment of adults. This is of in of that the more for of adults who primary care physicians because of a throat culture. of a throat swab on a remains the for the of the presence of group A streptococci in the and for the confirmation of the clinical diagnosis of acute streptococcal pharyngitis If done culture of a throat swab on a has a sensitivity of for the detection of the presence of group A β-hemolytic streptococci in the the of throat culture the in which the swab is has an on the of streptococci from the culture swab should be from the of and the pharyngeal of the oral and are not acceptable and these should not be with the swab or the have been care who in to a throat swab from an child may a specimen that is neither results may be the patient has antibiotics or at the the throat swab is has also been reported that the of and culture may the of positive culture results However, are with to the of the of and the culture in the of a the cost and with of and culture are to for physicians who throat in that the of the throat culture is the duration of the swab is a culture should be at for additional at however, a number of positive throat culture results that not have been therapeutic may be made on the basis of an culture, is to that negative results at at The clinical of the number of group A β-hemolytic streptococcal present on the throat culture is Although patients with acute group A streptococcal pharyngitis are likely to have positive than are patients who are is much overlap in the of of throat culture results that the cannot be made on this basis the most used test for of group A streptococci from other β-hemolytic streptococci in is the This test a on the basis of that of group A streptococci a of a of of A streptococci do not this alternative and of streptococcal is by detection of the carbohydrate antigen in bacterial are available for this are for by clinical but most physicians throat to the additional for the improvement in provided by with an antigen detection test A of a throat swab on is the or in the result. RADTs have been for the of group A β-hemolytic streptococci from throat Although these rapid are more than culture, provide results and treatment of patients with streptococcal pharyngitis the risk of the of group A β-hemolytic streptococci, the patient to to or and the acute with the The of RADTs for certain (e.g., patients in has been shown to the number of patients who are for streptococcal pharyngitis, with of throat The of the RADTs that are available have an specificity of with culture This that test results are therefore, therapeutic be made with confidence on the basis of a positive test result. the sensitivity of most of these is or even with culture has been that most of the RADT results for patients who are and are not However, studies of RADTs demonstrated that a of patients with RADT results infected with group A β-hemolytic streptococci and not The RADTs used relatively and on sensitivity and a more RADTs that and have become These may be more sensitive than other RADTs and even as sensitive as throat culture on However, in of the RADT and other available as well as the of studies the physicians who RADT for diagnosis in children and and who do not culture to negative results should do only in practice that the RADT has a sensitivity to that of throat culture Moreover, the should be for some of these the of does not the for of that are not of the conventional throat culture RADTs infected from with pharyngitis. allow physicians to antibiotics from the of patients with for results of culture or RADT are This is of of patients with who are in primary care receive for antimicrobials and not present and are of no in the diagnosis of acute pharyngitis. are for confirmation of streptococcal in patients of acute rheumatic or acute also are in epidemiological for patients with acute infection from patients who are The diagnosis of acute group A streptococcal pharyngitis should be on clinical and epidemiological and by performance of a laboratory A positive result of either throat culture or RADT confirmation of the presence of group A β-hemolytic streptococci in the pharynx. However, for children and a negative RADT result should be confirmed with a throat culture result, unless the physician has ascertained in his or her practice that the RADT used is comparable 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 The generally high specificity of RADTs should minimize overprescription of antimicrobials for treatment of adults to of diagnostic the of patients who have group A β-hemolytic streptococci in a course of antimicrobial therapy are Therefore, culture of throat is not for patients who have a complete course of therapy for group A streptococcal pharyngitis however, special in which should have of throat should be for patients with a of rheumatic and should also be for patients who acute pharyngitis of either acute rheumatic or acute as well as of group A streptococcal pharyngitis in or throat may also be when of group A streptococci has been occurring a throat are not for patients who have a complete course of therapy for group A streptococcal pharyngitis. therapy is for with pharyngitis the presence of the organism in the throat is confirmed by culture or RADT (figure 1). If is clinical or epidemiological that results in a high of antimicrobial therapy be the physician is for laboratory provided that the therapy is the diagnosis of streptococcal pharyngitis is not confirmed by results of a laboratory of antimicrobial therapy results in of signs and symptoms However, should be group A streptococcal pharyngitis is usually a and symptoms days of even without antimicrobial therapy This objective of clinical improvement with therapy even more therapy be for to days the of symptoms and the of the major acute rheumatic These allow the in antimicrobial therapy the evaluation of an patient with group A streptococcal pharyngitis. the therapeutic studies numerous antimicrobial agents have been in clinical and have been shown to be of eradication of group A streptococci from the However, the only recommended antimicrobial therapy that has been in studies and has been shown to of rheumatic is therapy These studies done with penicillin G in a that has since been by benzathine penicillin this no in are Although are not are that benzathine penicillin G is effective in primary prevention of rheumatic prevention of an of rheumatic group A streptococcal penicillin G has also been shown to the of cases of rheumatic streptococcal in Moreover, benzathine penicillin G has been proven effective in prevention of rheumatic in patients who have a of the as antimicrobials eradicate group A streptococci from the and is that eradication is a for in primary prevention of rheumatic for antimicrobial therapy for group A streptococcal pharyngitis. has not been a in the treatment of group A streptococcal pharyngitis in the clinical of group A in the has been to be to penicillin. Although relatively high of to and antibiotics have been reported from of group A streptococci in the have been shown to be to Although have been of in the is no that this is at the present time. However, the of macrolides and for and physicians should be of of antimicrobial and are not recommended for treatment of group A streptococcal pharyngitis because of the rates of antimicrobial to these agents group A streptococci and the frequent of these agents to eradicate even from the pharynx. an antimicrobial for treatment of group A streptococcal pharyngitis, to include efficacy, safety, antimicrobial spectrum with therapy and cost. These the of antimicrobial therapy. A number of antibiotics have been shown to be effective in treating group A streptococcal pharyngitis. These include penicillin and its congeners (such as and as well as numerous cephalosporins and macrolides and clindamycin. Penicillin, however, remains the treatment of choice because of its proven efficacy and safety, and its narrow spectrum and low cost Amoxicillin is often used in place of penicillin V as oral therapy for young children; the efficacy appears to be equal. This choice is primarily related to acceptance of the taste of the suspension. Erythromycin is a suitable alternative for patients allergic to penicillin. First-generation cephalosporins are also acceptable for patients allergic to penicillin who do not immediate-type hypersensitivity to β-lactam antibiotics. the patient infected with an of group A who is to β-lactam is an Most oral antibiotics must be administered for the conventional 10 days to achieve maximal rates of pharyngeal eradication of group A streptococci. has been reported that and are effective in group A streptococci from the when administered for <5 only the are for a course of therapy by the and at this However, studies of therapy include no of with therapy, and do not include for which treatment and the of these antibiotics are much broader than is the spectrum of penicillin, even when the antibiotics are administered for short courses, are more Therefore, of these shorter courses of oral antimicrobial therapy cannot be at this to treat pharyngitis to group A β-hemolytic streptococci with a dose of penicillin have been have demonstrated that once-daily and once-daily of cephalosporins (e.g., and are effective in pharyngeal streptococci. only and are as once-daily therapy for streptococcal pharyngitis in Preliminary investigations have demonstrated that once-daily amoxicillin therapy is effective treatment for group A β-hemolytic streptococcal pharyngitis [2, 3]. If its is confirmed by additional investigations, once-daily amoxicillin therapy, because of its low cost and relatively narrow spectrum, could become an alternative regimen for the treatment of group A β-hemolytic streptococcal pharyngitis. for group A streptococcal may be either or recommended for antimicrobials proven to be effective for the treatment of uncomplicated group A streptococcal pharyngitis and for the of the and the on which the recommendations are Intramuscular benzathine penicillin G therapy is preferred for patients unlikely to complete a full 10-day course of oral therapy. Patients with acute streptococcal pharyngitis should receive therapy with an antimicrobial agent at a dose and for a duration that is likely to eradicate the infecting organism from the pharynx. the basis of its narrow spectrum of antimicrobial the with which adverse and its penicillin is the of choice for treatment of patients who are not allergic to of in the of patient group A streptococci in however, is not necessary to test these contacts for group A streptococcal or to treat have positive test in which testing of an patient is the in Diagnosis of Group A Streptococcal is recommended that culture be for contacts and treatment be administered to with positive culture contacts of patients with group A streptococcal as or may be at risk of or infection with the of contacts the of this guideline and has been in Except in in which is risk of frequent or of streptococcal culture of throat swab from or treatment of contacts of patients with group A streptococcal pharyngitis is not recommended performance of throat culture for have a course of antibiotic therapy is not necessary in special the in Diagnosis of Group A Streptococcal Because is no only patients who have signs and symptoms of acute pharyngitis that in the of therapy are likely to patients have culture or RADT results positive for group A streptococci, are of in the of infection with the antimicrobial regimen or a infection with group A streptococci from the or A of pharyngitis by the infecting of group A treatment cannot be but this do not antimicrobial therapy. have group A β-hemolytic streptococci present in but have no of to the organism the and in as as of children may be may be by group A β-hemolytic streptococci for that may of pharyngitis. may that these patients have group A β-hemolytic streptococci in and appear to have acute streptococcal pharyngitis. are unlikely to the organism to close contacts and are at low for suppurative complications or complications (e.g., acute rheumatic Moreover, is much more to eradicate group A streptococci from the of than from patients with acute This has been shown to be for penicillin therapy and may also be for some other clinical and epidemiological in of the published studies that penicillin has relatively high rates for group A streptococci from the the patient likely with is to a with an infection from a patient with acute streptococcal pharyngitis. include patient of the (e.g., the of and the of the signs and symptoms however, the may not be able to from acute infection and to course of of pharyngitis that are with laboratory confirmation of group A streptococci and that of a course of antimicrobial therapy, treatment with of the agents in is Because patient with oral antimicrobial therapy often is an a regimen of benzathine penicillin G should be these is not necessary to additional throat swab for culture the course of therapy unless the patient remains or or unless special are present the in Diagnosis of Group A Streptococcal even more clinical is the a child or a of to of acute pharyngitis for which culture or RADT results are positive for group A streptococci. is likely that most of these patients are a patient with frequent the clinical to antibiotic therapy and the presence or of group A streptococci in of throat is in from of acute pharyngitis. or of streptococcal from from an patient may also in at this but studies are available only from research If a physician that of is the for of group A streptococcal in a may be to from contacts and treat for culture results are positive is no that are for group A streptococci or that to antimicrobial is not recommended to the of rheumatic in patients who have a of rheumatic of the may be for the patient do not in and for no alternative for the pharyngitis is may the number of of pharyngitis in some patients, but only for a have been no definitive studies of treatment of of acute pharyngitis in the However, the in have been reported to result in low rates of bacteriologic A small percentage of patients have a of acute pharyngitis with results of throat culture positive for group A streptococci a short of a course of antimicrobial therapy. A may be with the in the course of or may be to in a from group A streptococcal antimicrobial agents have been shown to high rates of pharyngeal eradication of streptococci under these that these agents are in for treatment of with of pharyngitis proven by culture or rapid antigen detection of the of care of patients with acute pharyngitis include the for patients of group A streptococcal pharyngitis, performance of throat or for patients with acute pharyngitis and positive for group A streptococci, of one of the antimicrobial recommended in for patients with negative test results for group A streptococci, or of antimicrobial for patients who have an course of antimicrobial therapy, of performance of or for contacts of patients with group A streptococcal pharyngitis, of throat or and of of antimicrobial to of acute pharyngitis for patients with a of rheumatic