Diagnosis and Management of Group A Streptococcal Pharyngitis: A Practice Guideline

This is the second in a series of practice guidelines commissioned by the Infectious Diseases Society of America through its Practice Guidelines Committee. The purpose of these guidelines is to provide assistance to clinicians when making decisions on treating the conditions specified in each guideline. The targeted providers are pediatricians, family practitioners, and internists. The targeted patients and setting for the acute pharyngitis guideline are pediatric, adolescent, and adult outpatients with a complaint of sore throat. Funding was provided by the IDSA. Panel members represented experts in adult and pediatric infectious diseases. The guidelines are evidence-based. A standard ranking system was used for the strength of the recommendations and the quality of the evidence cited in the literature reviewed. The document has been subjected to external review by peer reviewers as well as by the Practice Guidelines Committee and was approved by the IDSA Council. An executive summary, algorithms, and tables highlight the major recommendations.

## Most oral antibiotics must be administered in the conventional
Outcomes 10-day course to achieve maximal pharyngeal eradication of group
The desired outcomes are: (1) prevention of acute rheumatic A streptococci, but the use of certain newer agents has been reported fever; [bib_ref] Purpose of quality standards sensitivity with respect to true infections, Gross [/bib_ref] prevention of suppurative complications (e.g., peritonsillar to achieve comparable bacteriologic and clinical cure rates among abscess, cervical lymphadenitis, or mastoiditis); (3) abatement of patients with streptococcal pharyngitis when these agents are given clinical symptoms and signs; (4) a rapid decrease in infectivity so for 5 days. However, definitive results from comprehensive studas to reduce transmission of group A b-hemolytic streptococci to ies are not available; thus, final evaluation of these proposed shorter family members, classmates, and other close contacts and to allow courses of oral antibiotic therapy is not possible, and they cannot the rapid resumption of usual activities; (5) minimization of potenbe recommended at this time. Moreover, these antibiotics have tial adverse effects of inappropriate antimicrobial therapy. much broader spectrums than penicillin, and most, even when administered for short courses, are more expensive.
Except under special circumstances, neither repeated bacteri-Evidence ologic testing (culture or RADT) of patients who have success-We reviewed a large number of clinical trials of diagnostic fully completed a course of antimicrobial therapy nor routine and treatment strategies for group A streptococcal pharyngitis. testing of asymptomatic household contacts of patients with
The reports were examined for indicators of quality. For examgroup A streptococcal pharyngitis is recommended.
ple, studies of treatment were evaluated for randomization, A small percentage of patients will have recurrences of acute blinding, use of streptococcal typing to differentiate treatment pharyngitis that are associated with throat cultures (or RADTs) failures from new infections, duration and timing of follow-up positive for group A streptococci within a short period following examinations, and statistical power [bib_ref] Streptococcal pharyngitis: current therapy and criteria for evalua-27, Peter [/bib_ref] [bib_ref] Purpose of quality standards sensitivity with respect to true infections, Gross [/bib_ref]. completion of a course of antimicrobial therapy. Such episodes may be treated with one of the antimicrobial agents appropriate for treatment of the initial illness. If these episodes were previously Values treated with oral agents and compliance is in question, retreatment
In evaluating diagnostic options, we placed a high value with intramuscular benzathine penicillin G should be considered.
on selecting the diagnostic test that was most accurate for When multiple episodes occur over the course of months or years, differentiating acute pharyngitis due to group A b-hemolytic it may be difficult to differentiate viral infections in a streptococcal streptococci from that due to other agents. For evaluation of carrier from true group A streptococcal infections. Certain antimitreatment, particularly high values were assigned to proven crobial agents, such as clindamycin and amoxicillin/clavulanate, clinical and bacteriologic efficacy, safety, spectrum of antimimay be beneficial because they have been shown to yield high crobial activity, and relative cost. rates of pharyngeal eradication of streptococci under these particular circumstances.

## Benefits and costs
The group A b-hemolytic streptococcus is the most common Definition bacterial cause of acute pharyngitis [bib_ref] immunoassay for rapid detection of group A b-hemolytic streptococci: 97(6pt2)(suppl):949 -54. should..., Bisno [/bib_ref]. Accurate diagnosis, followed by appropriate antimicrobial therapy, is important for Group A streptococcal pharyngitis (pharyngotonsillitis) is an acute infection of the oropharynx and/or nasopharynx with the reasons previously stated (see the section on outcomes). Although acute pharyngitis is one of the most frequent illnesses Streptococcus pyogenes.
for which pediatricians and other primary care physicians are consulted, less than half of patients with this condition are infected by group A streptococci. Moreover, the signs and Objective symptoms of group A streptococcal and nonstreptococcal pharyngitis overlap so broadly that accurate diagnosis on clinical The objective of this practice guideline is to provide recommendations for the accurate diagnosis and optimal treatment grounds alone is usually impossible [bib_ref] Perplexity and precision in the diagnosis of streptococ-29, Wannamaker [/bib_ref].
With the exception of very rare infections by certain of the of group A streptococcal pharyngitis.
other pharyngeal bacterial pathogens listed in table 1 (e.g., Corynebacterium diphtheriae and Neisseria gonorrhoeae), antimicrobial therapy is of no proven benefit in the treatment of acute Options pharyngitis due to bacteria other than the group A streptococcus. It is therefore extremely important for physicians to be able to Physicians caring for patients with acute pharyngitis must formulate differential diagnoses and determine which, if any, exclude the diagnosis of group A streptococcal pharyngitis to prevent inappropriate administration of antimicrobials to large confirmatory tests should be performed. If clinical and laboratory evaluations result in a diagnosis of group A b-hemolytic numbers of patients with pharyngitis. The administration of such therapy unnecessarily exposes patients to the associated expense streptococcal pharyngitis, one of several antimicrobial agents and treatment schedules may be selected. and hazards, and it may also contribute to the emergence of / 9c37$$se43 08-25-97 15:12:42 cidal UC: CID temperate climates, it usually occurs in the winter and early spring. Patients with group A b-hemolytic streptococcal pharyngitis commonly present with sore throats (generally of sudantibiotic-resistant bacteria that is being reported with increasing den onset), pain on swallowing, and fever. Headache, nausea, frequency in the United States and elsewhere.
vomiting, and abdominal pain may also be present, especially If a diagnosis of group A streptococcal pharyngitis is conin children. Physical examination reveals tonsillopharyngeal firmed, the clinician must select the most appropriate antimicroerythema with or without exudates and tender enlarged anterior bial agent known to be effective against the group A streptococcervical lymph nodes (lymphadenitis). Other findings may incus. The cost of an effective course of antimicrobial therapy clude a beefy red swollen uvula, petechiae on the palate, excorimay vary as much as 20-fold, depending on the drug chosen.
ated nares (especially in infants), and a scarlatiniform rash. The regimens recommended herein are judged to be optimal However, none of these findings is specific for group A bin regard to specificity, safety, and cost. hemolytic streptococcal pharyngitis, and they may occur with other upper respiratory infections. Conversely, the absence of Recommendations fever or the presence of clinical features such as conjunctivitis, cough, hoarseness, coryza, anterior stomatitis, discrete ulcera-

## A. diagnosis
tive lesions, viral exanthem, and diarrhea strongly suggests a viral rather than a streptococcal etiology. Differential diagnosis. Viruses are the most common nonbacterial causes of acute pharyngitis (table 1) [bib_ref] immunoassay for rapid detection of group A b-hemolytic streptococci: 97(6pt2)(suppl):949 -54. should..., Bisno [/bib_ref]. Respiratory viruses such as adenovirus, parainfluenza virus, rhinovirus, and Who Should Be Tested for Group A b-Hemolytic Streptococcal respiratory syncytial virus frequently cause acute pharyngitis.

## Pharyngitis?
Other viral agents of acute pharyngitis include coxsackievirus and ECHO viruses as well as herpes simplex virus. Epstein-When attempting to decide whether to perform a laboratory test for a patient who presents with acute pharyngitis, the clini-Barr virus is a frequent cause of acute pharyngitis that is often accompanied by the other clinical features of infectious mono-cal and epidemiological findings mentioned above should be considered before the test is performed. A history of close nucleosis (e.g., generalized lymphadenopathy and splenomegaly). Systemic infections with measles virus, cytomegalovirus, contact with a well-documented case of streptococcal pharyngi-/ 9c37$$se43 08-25-97 15:12:42 cidal UC: CID tis is helpful, as is an awareness of a high prevalence of group A positive throat cultures that would not otherwise be identified. Thus, while initial therapeutic decisions may be made on the b-hemolytic streptococcal infections in the community. Testing usually need not be performed for patients with acute pharyngi-basis of the results of an overnight culture, it is advisable to reexamine plates at 48 hours that are negative at 24 hours [bib_ref] Suitability of throat culture procedures for detection of group streptococcal pharyngitis and..., Kellogg [/bib_ref] tis whose clinical and epidemiological features do not suggest a group A streptococcal etiology. Selective use of diagnostic (category A, grade II).
The clinical significance of the number of group A b-hemostudies for group A b-hemolytic streptococci will result in an increase in both the proportion of positive test results and the lytic streptococcal colonies present on the throat culture plate is problematic. While cultures are more likely to be strongly percentage of patients with positive tests who are truly infected rather than merely streptococcal carriers (category A, grade II).
positive for patients with true acute group A streptococcal pharyngitis than for patients who are streptococcus carriers, Efforts have been made to incorporate clinical and epidemiological features of acute pharyngitis into scoring systems that there is so much overlap that the differentiation cannot be made accurately on the basis of the degree of positivity of the throat attempt to predict the probability that a particular illness is caused by group A b-hemolytic streptococci [bib_ref] A simple scorecard for the tentative diagnosis of streptococcal tococcic infection, Breese [/bib_ref] [bib_ref] Streptococcal pharyngitis: evaluation of clinirheumatic fever by treatment of the preceding streptococcal..., Stillerman [/bib_ref]. How-culture alone [bib_ref] Diagnosis of pharyngitis: methodology of throat cultures, Gerber [/bib_ref] (category A, grade II).
The most widely used test for differentiating group A strepto-ever, at best these clinical scoring systems predict positive results of throat cultures or RADTs only 80% of the time.
cocci from other b-hemolytic streptococci in physicians' offices is probably the bacitracin disk test. This test provides a Therefore, unless the diagnosis of group A streptococcal pharyngitis can be confidently excluded on clinical and epidemio-presumptive identification based on the observation that u95% of group A streptococci show a zone of inhibition around a logic grounds (see Clinical Diagnosis above), bacteriologic studies should be performed (category A, grade II). disk containing 0.04 units of bacitracin, while 83% -97% of non-group A streptococci do not [bib_ref] extraction method with pronase B for grouping beta-hemolytic strepto-42. World Health Organization...., Ederer [/bib_ref] [bib_ref] Bacitracin differentiazation, 1988. tion of presumptive identification of group A b-hemolytic streptococci:..., Murray [/bib_ref]. An alternative and highly specific method of identifying Throat Cultures streptococcal serogroups is the detection of the group-specific cell-wall carbohydrate antigen directly on isolated bacterial Culture of a throat swab on a sheep blood agar plate remains the standard for the documentation of the presence of group A colonies. Commercial kits containing group-specific antisera are available for this purpose. Such tests are appropriate for streptococci in the upper respiratory tract and for the confirmation of the clinical diagnosis of acute streptococcal pharyngitis use by microbiology laboratory personnel, but most physicians who perform throat cultures would find it difficult to justify [bib_ref] Controlled studies of streptococinfections on clinical grounds, Breese [/bib_ref] (category A, grade II). A single throat swab cultured correctly on a blood agar plate has a sensitivity of 90% -95% in the additional expense for the minimal improvement in accuracy that serogrouping with an antigen detection test would detecting the presence of group A b-hemolytic streptococci in the pharynx [bib_ref] Comparison of throat cultures and rapid strep tests for diagnorate of rheumatic..., Gerber [/bib_ref] (category A, grade II).
provide [bib_ref] Diagnosis of pharyngitis: methodology of throat cultures, Gerber [/bib_ref]. Several variables impact on the accuracy of the throat culture results. For example, the manner in which the swab is obtained

## Rapid antigen detection tests
has an important impact on the yield of streptococci from the throat culture [bib_ref] Streptococcal pharyngitis: optimal site for throat culof rheumatic fever by treatment of..., Brien [/bib_ref] [bib_ref] Cultures of Streptococcus 466 -71. pyogenes from the oropharynx, Gunn [/bib_ref]. Throat swab specimens should be ob-A disadvantage of culturing a throat swab on blood agar plates is the delay (overnight or longer) in obtaining the culture tained from the surface of both tonsils (or tonsillar fossae) and the posterior pharyngeal wall. Other areas of the oropharynx results. RADTs have been developed for the identification of group A b-hemolytic streptococci directly from throat swabs. and mouth are not acceptable sites for sampling, and these sites should not be touched before or after the appropriate areas Although these rapid tests are more expensive than blood agar cultures, the advantage they offer over the traditional procedure have been sampled. In addition, false-negative results may be obtained if the patient has received antibiotics shortly before is the speed with which they can provide results. Rapid identification and treatment of patients with streptococcal pharyngitis or at the time the throat swab specimen is collected.
It has also been reported that the use of anaerobic incubation can reduce the risk of the spread of group A b-hemolytic streptococci, allowing these patients to return to school or work and selective culture media may increase the proportion of positive cultures [bib_ref] Effect of atmosphere of incubation from rheumatic fever: routine administration of benzathine..., Schwartz [/bib_ref] [bib_ref] Effect of atmosphere and duration of fever in children and adolescents. A..., Lauer [/bib_ref]. However, the data on the impact of sooner, and can reduce the acute morbidity associated with this illness (category A, grade II). The use of RADTs the incubation atmosphere and the culture media are conflicting, and, in the absence of a definite benefit, the increased cost vs. throat cultures for certain populations (e.g., patients seen in emergency departments) has been shown to significantly and effort associated with anaerobic incubation and selective culture media are difficult to justify, particularly for physicians increase the number of patients appropriately treated for streptococcal pharyngitis [bib_ref] Clinical evaluation of a latex aggluti-References nation test for streptococcal pharyngitis: performance..., Lieu [/bib_ref]. who process throat cultures in their own offices [bib_ref] Effect of atmosphere of incubation from rheumatic fever: routine administration of benzathine..., Schwartz [/bib_ref] [bib_ref] Ann Intern Comparison of throat culture methods for the recovery of group..., Roddey [/bib_ref] [bib_ref] Diagnosis of pharyngitis: methodology of throat cultures, Gerber [/bib_ref] (category A, grade II).
Most of the RADTs that are currently available have an excellent specificity ( 95%) when compared with blood agar Another variable that can impact on the yield of the throat culture is the duration of incubation. tomatic pharyngitis after the organism's presence in the throat The first RADTs were based on latex agglutination methodis confirmed by microbiological or immunologic means (figure ology, were relatively insensitive, and had unclear endpoints. 1). When there is clinical or epidemiological evidence that Newer tests based on EIA techniques offer more sharply deresults in a high index of suspicion, antimicrobial therapy can fined endpoints as well as increased sensitivity. More recently, be initiated while laboratory confirmation is pending provided RADTs for which optical immunoassay and chemiluminescent such therapy is discontinued if the diagnosis of streptococcal DNA probes are used have become available. Data on these pharyngitis is not confirmed. Early initiation of antimicrobial newer tests suggest that they may be more sensitive than other therapy results in faster resolution of the signs and symptoms RADTs and perhaps even as sensitive as standard throat cul- (category A, grade I) of the infection, but two facts tures on sheep blood agar plates. However, in view of someshould be recalled. First, group A streptococcal pharyngitis is what conflicting data, additional corroborative information usually a self-limited disease; fever and constitutional sympis needed before these tests can be recommended for routine use toms disappear spontaneously within 3 or 4 days of onset, even without confirmatory throat cultures for negative test results.
when antimicrobial therapy is not administered . Second, Titers of antibodies to streptococci reflect past and not presit has been shown that therapy can be safely postponed 9 days ent immunologic events and are of no value in the diagnosis after the onset of symptoms and still prevent the occurrence of of acute pharyngitis. These titers are valuable for confirming the major nonsuppurative sequel, acute rheumatic feverprior streptococcal infections in patients suspected of having (category A, grade I). acute rheumatic fever or acute glomerulonephritis. They also These facts allow the clinician flexibility in initiating therapy are helpful in prospective epidemiological studies that are conduring the evaluation of an individual patient with presumed ducted to separate patients with acute infection from those who group A streptococcal pharyngitis. The results of the initial are carriers.
therapeutic studies were reported nearly 50 years ago; since Guideline: The diagnosis of acute group A streptococcal then numerous antimicrobial agents have been examined in pharyngitis should be suspected on clinical and epidemiological grounds and then supported by the results of a laboratory test. Either a positive throat culture or RADT provides adequate confirmation of the presence of group A b-hemolytic streptococci in the pharynx, but a negative RADT result should be confirmed with a throat culture (category A, grade II).

## Repeated diagnostic testing
Most asymptomatic patients with group A b-hemolytic streptococci present in the upper respiratory tract after a complete course of appropriate therapy are streptococcal carriers [29, 30]. Therefore, follow-up throat cultures are not routinely indicated for asymptomatic patients who have received a complete course of therapy for group A streptococcal pharyngitis (category A, grade II). However, there are special situations when follow-up throat cultures should be performed for asymptomatic patients. Throat CID clinical trials and have been shown to be capable of eradicating been shown to be resistant to erythromycin. Sulfonamides and tetracyclines are not recommended for treatment of group group A streptococci from the upper respiratory tract. However, it must be recognized that the only antimicrobial actually exam-A streptococcal pharyngitis because of the higher rates of resistance to these agents among group A streptococci and the ined in controlled studies and shown to be capable of preventing initial attacks of rheumatic fever has been intramuscular reposi-frequent failure of these agents to eradicate even susceptible organisms from the pharynx. tory penicillin (category A, grade I). These studies were performed with procaine penicillin G in oil containing Antimicrobial therapy. When selecting an antimicrobial for treatment of group A streptococcal pharyngitis, important is-aluminum monostearate , a preparation that has since been supplanted by benzathine penicillin G. (For this reason, sues include efficacy, safety, antimicrobial spectrum (narrow vs. broad), dosing schedules, compliance (or adherence), and no regimens listed in table 2 have been assigned a grade of A1.) There are data, although not definitive, indicating that cost. These factors influence the cost-effectiveness of antimicrobial therapy. benzathine penicillin G is effective in primary prevention of rheumatic fever (prevention of an initial attack of rheumatic A number of antibiotics have been shown to be effective for treating group A streptococcal pharyngitis. These agents in-fever following an episode of group A streptococcal pharyngitis) . Benzathine penicillin G has also been shown clude penicillin and its congeners (such as ampicillin and amoxicillin), as well as numerous cephalosporins, macrolides, and to decrease the occurrence of rheumatic fever cases during epidemics of streptococcal pharyngitis in military recruit camps clindamycin. However, penicillin remains the treatment of choice because of its proven efficacy, safety, narrow spectrum,. Moreover, benzathine penicillin G has been proven effective for preventing rheumatic fever in patients who have had and low cost [31, . Erythromycin is a suitable alternative for patients who are allergic to penicillin. First-or second-a previous attack of the disease (secondary prophylaxis)(category A, grade I). Other antimicrobials can effectively erad-generation cephalosporins are also acceptable for penicillinallergic patients who do not manifest immediate hypersensitiv-icate group A streptococci from the upper respiratory tract, and it is assumed that such eradication is an adequate measure of ity to b-lactam antibiotics.
Most oral antibiotics must be administered for 10 days to effectiveness in the primary prevention of rheumatic fever.
Antimicrobial resistance has not been a significant issue in achieve maximal pharyngeal eradication of group A streptococci, but certain new agents have been administered in shorter the treatment of group A streptococcal pharyngitis in the United States. There has never been a clinical isolate of group A courses. It has been reported that azithromycin , cefuroxime, cefixime [bib_ref] Efficacy of tonsillectomy pharyngitis and/or tonsillitis: comparison with 10-day penicillin for recurrent..., Adam [/bib_ref] , and cefpodoxine [bib_ref] course treatment of acute group A b-hemolytic streptococcal tonsil-Clindamycin treatment of chronic..., Pichichero [/bib_ref] can be used to streptococcus documented to be resistant to penicillin anywhere in the world. Although there have been geographic areas where achieve comparable bacteriologic and clinical cure rates among patients with streptococcal pharyngitis when these drugs are isolates have been highly resistant to macrolide antibiotics (specifically erythromycin), this has not been and currently is not given for 5 days. However, definitive results from comprehensive studies are not available, and thus it is not possible to a clinically significant problem in North America. Less than 5% of group A streptococci isolated in the United States have endorse these proposed shorter courses of oral antibiotic ther- * Amoxicillin is often used in place of oral penicillin V in young children; the efficacy of amoxicillin appears to be equal to that of penicillin V, and this choice is primarily related to acceptance of the taste of the suspension.  See text.  For patients weighing less than 60 lbs (27 kg).  Two milliliters of C-R bicillin(900/300) contains 900,000 units of benzathine penicillin G and 300,000 units of procaine penicillin G; this preparation thus contains less benzathine penicillin G than is conventionally used in the treatment of adolescents or adults.
Available data indicate that orally administered first-and second-generation cephalosporins also are effective in eradicating group A streptococci from the upper respiratory tract; these agents should not be used in patients with immediate hypersensitivity to b-lactam antibiotics.
First-generation cephalosporin A II Second-generation cephalosporin A II. # These are total daily doses (maximum daily dose, 1 g per day).
/ 9c37$$se43 08-25-97 15:12:42 cidal UC: CID apy at this time. Moreover, the spectra of these antibiotics are special circumstances are present (see the section on Repeated Diagnostic Testing). Because routine retesting is no longer much broader than that of penicillin, and, even when they are administered for short courses, they are more expensive.
advised, only those patients whose signs and symptoms of acute pharyngitis return within the succeeding few weeks will Antimicrobials for group A streptococcal upper respiratory tract infections may be given either orally or parenterally. , noncompliance with the pre-group A streptococcal pharyngitis. Intramuscular benzathine penicillin G is preferred for patients who are unlikely to com-scribed antimicrobial regimen [52], or a new infection with a group A streptococcus acquired from family, classroom, or plete a full 10-day course of oral therapy.
Guideline: patients with acute streptococcal pharyngitis community contacts. A second episode of pharyngitis with the original infecting group A streptococcal strain (i.e., treatment should receive therapy with an antimicrobial agent in a dosage and for a duration that is likely to eradicate the infecting organ-failure) cannot be ruled out, but this occurs only rarely. Streptococcal carriers do not ordinarily require further anti-ism from the pharynx. On the basis of penicillin's narrow spectrum of antimicrobial activity, the infrequency with which microbial therapy. These individuals have group A b-hemolytic streptococci present in their throats but have no evidence of it produces adverse reactions, and its modest cost, it is the drug of choice for nonallergic patients.
an immunologic reaction to this organism . During the winter and spring in temperate climates, 20% of asymptom-Management of close contacts and pharyngeal carriers. Approximately 25% of individuals within the household of an index atic school-aged children may be streptococcus carriers. They may be colonized by group A b-hemolytic streptococci for patient may also harbor group A streptococci in their upper respiratory tracts. However, it is usually not necessary to perform several months, and during that period they may have episodes of intercurrent viral pharyngitis. When tested, these patients throat cultures for these contacts or treat them if they are asymptomatic. In those situations in which repeated testing is indicated are found to have group A b-hemolytic streptococci in their pharynges and appear to have acute streptococcal pharyngitis. (see the section on Repeated Diagnostic Testing), performing cultures for asymptomatic family contacts and treating those who Streptococcal carriers are unlikely to spread the organism to their close contacts and are at low risk, if any, for developing are positive are advisable. When a larger group (e.g., schools, day care centers, or domiciliary institutions) is involved in a suppurative complications or nonsuppurative complications (e.g., acute rheumatic fever) . documented outbreak of group A streptococcal upper respiratory infections or scarlet fever, throat cultures should be performed Moreover, it is more difficult to eradicate group A streptococci from the upper respiratory tracts of streptococcal carriers for all patients; however, only those with positive throat cultures should be treated with antimicrobials. The administration of intra- . This has been shown to be true with penicillin therapy and also may be true with some other antimicrobials. In fact, muscular injections of benzathine penicillin G has been shown to be very effective in terminating such outbreaks.
many of the published studies showing relatively high rates of failure to eradicate group A streptococci from the upper Strains of group A streptococci that cause invasive infections may spread to close contacts of the index case. Secondary cases respiratory tract with penicillin therapy were likely ''contaminated'' with carriers. of severe invasive infection have rarely occurred in family and institutional contacts and in health care workers . Data
In practice it is difficult to differentiate a carrier with an intercurrent non-group A streptococcal infection from a patient are as yet too limited to assess with precision the risk of secondary illness or to make a firm recommendation regarding the with acute streptococcal pharyngitis. Helpful clues include the patient's age, season of the year, local epidemiology (e.g., the advisability of routinely performing cultures and treating close contacts of patients with group A streptococcal infections such presence of influenza or enteroviral illnesses), and the precise nature of the presenting signs and symptoms (see the section as necrotizing fasciitis or the toxic shock -like syndrome.
Guideline: It is not necessary to perform throat cultures or on clinical diagnosis above). In many instances, however, the clinician may not be able provide treatment for household contacts of patients with group A streptococcal pharyngitis, except in specific situations in confidently to distinguish persistent carriage from acute infection and will elect to administer another course of antimicrobi-which there is increased risk of frequent infections or of nonsuppurative sequelae (category B, grade III).
als. For single episodes of symptomatic, culture-confirmed or RADT-confirmed group A streptococcal pharyngitis that occur shortly after completion of a course of appropriate antimicro-

## C. management of patients with repeated episodes of acute
bial therapy, any of the agents listed in table 2 is appropriate.

## Pharyngitis and cultures or radts positive for group a
Because patient compliance with oral antimicrobials often is b-Hemolytic Streptococci an issue, a regimen of intramuscular benzathine penicillin G should be considered. For these single repeated episodes, it is Performing routine throat cultures (or rapid antigen testing) for asymptomatic patients after completion of antibiotic therapy not necessary to reculture the throat after the second course of therapy unless the patient remains or becomes symptomatic or for group A streptococcal pharyngitis is not necessary unless / 9c37$$se43 08-25-97 15:12:42 cidal UC: CID unless special circumstances are present (see the section on There have been no definitive controlled studies of therapy for multiple, repeated symptomatic episodes of culture-positive Repeated Diagnostic Testing above).
An even more challenging clinical circumstance is a pa-acute pharyngitis in the same patient; however, the regimens listed in [fig_ref] Table 3: Retreatment of symptomatic patients with multiple repeated culture-positive episodes of pharyngitis [/fig_ref] have been reported to result in low bacteriologi-tient -usually a school-aged child or adolescent -who has multiple episodes of acute pharyngitis and cultures or RADTs cal failure rates [55 -58].
Guideline: A small percentage of patients will have recur-positive for group A streptococci within a period of months to years. It is likely that most patients in this category are rences of acute pharyngitis and throat cultures (or RADTs) positive for group A streptococci within a short period of time streptococcal carriers with nonstreptococcal infections. For patients who have frequent distinct episodes of infection, informa-following completion of a course of antimicrobial therapy. A single such episode may be retreated with the regimens listed tion regarding the clinical response to antibiotic therapy and the presence or absence of group A streptococci in throat cultures in table 2. When multiple episodes occur over the course of months or years, it may be difficult to differentiate viral infec-performed during asymptomatic intervals is helpful in distinguishing persistent carriage from repeated episodes of strepto-tions from true group A streptococcal infections in a streptococcal carrier. Use of certain antimicrobial agents has been shown coccal pharyngitis. Serotyping of repeated streptococcal isolates from an individual patient may also assist in arriving at to yield high rates of streptococcal eradication in the pharynx under these particular circumstances (category A, grade II). this determination, but such studies can be done only in specialized research laboratories.
Suggested regimens with these agents are listed in table 3. When physicians suspect Ping-Pong spread to be associated with multiple repeated episodes of group A streptococcal infections in one family, performing simultaneous cultures for all D. Indicators of Quality family contacts and treating those whose cultures are positive may be helpful (category B, grade III). There is no credible Indicators of quality of care for patients with acute pharyngitis include: (1) performance of throat cultures or RADTs for evidence that family pets are reservoirs for group A streptococci or that they contribute to familial spread.
patients suspected of having group A streptococcal pharyngitis;
(2) performance of throat cultures for patients with negative Continuous antimicrobial prophylaxis for group A streptococcal infection is not recommended because there is insuffi-RADTs; (3) prescription of one of the antimicrobial regimens recommended in table 2 for patients with acute pharyngitis cient evidence to show that it is effective, except for preventing recurrences of acute rheumatic fever. Surgical removal of the and positive tests for group A streptococci; (4) withholding or discontinuing antimicrobial therapy for patients with throat tonsils may be considered for the rare patient whose symptomatic episodes do not diminish in frequency over time and for cultures negative for group A streptococci; (5) omission of routine follow-up cultures for patients who have received an whom no alternative explanation for the recurrent pharyngitis is evident. Tonsillectomy may decrease recurrences of symp-adequate course of antimicrobial therapy; (6) avoidance of routine throat cultures for asymptomatic family contacts of patients tomatic pharyngitis in selected patients, but only for a limited period of time [54] (category A, grade I).
with group A streptococcal pharyngitis; (7) avoidance of con-  Although shorter courses of some newer macrolides and cephalosporins have been reported to be effective for treating group A streptococcal upper respiratory tract infections, the evidence is not yet sufficient to recommend these agents for therapy at this time (this is also true for patients with repeated infections or for those in whom the organism is difficult to eradicate).  Maximum dose, 750 mg of amoxicillin per day.  Benzathine penicillin G is useful for patients whose compliance with previous courses of oral antimicrobials is questionable. Limited data suggest that the addition of rifampin 
[fig] Figure 1: Diagnosis and management of acute pharyngitis. This cultures should be performed routinely for patients with histories algorithm applies to uncomplicated cases of acute pharyngitis; addiof rheumatic fever. Such cultures should also be considered for tional diagnostic and therapeutic measures may be necessary for papatients who develop acute pharyngitis during outbreaks of either tients with suppurative complications (e.g., peritonsillar abscess or acute rheumatic fever or poststreptococcal acute glomerulonephricervical lymphadenitis) or when infection with uncommon pharyngeal tis as well as during outbreaks of group A streptococcal pharyngitis bacterial pathogens (e.g., Corynebacterium diphtheriae or Neisseria gonorrhoeae) is suspected. (0 A if negative; / A if positive). in closed or semiclosed communities [30, 31]. Follow-up throat [/fig]
[table] Table 1: Microbial etiology of acute pharyngitis. rubella virus, influenza virus, and a number of other viral agents may be associated with acute pharyngitis. Other agents such Microbe Disorder as Mycoplasma pneumoniae and Chlamydia pneumoniae are uncommon causes of acute pharyngitis.Clinical diagnosis. There are certain characteristic epide- [/table]
[table] Table 2: Antimicrobial therapy for group A streptococcal pharyngitis. [/table]
[table] Table 3: Retreatment of symptomatic patients with multiple repeated culture-positive episodes of pharyngitis. * Macrolides (e.g., erythromycin) and cephalosporins are not included in this table, as there are insufficient data to support their efficacy in this specific circumstance. [/table]
[table] 10: mg/kg b.i.d. 1 4 days; maximum dose, 300 mg b.i.d.) to a benzathine penicillin G regimen may be beneficial for eradicating streptococci from the pharynx [58]. [/table]