Testing Followed by Penicillin Remains Standard for Streptococcal Pharyngitis

Emma Hitt, PhD

February 17, 2011

February 17, 2011 — For the treatment of streptococcal pharyngitis, specific testing remains important before treatment with an antibiotic, which can entail penicillin or a first-generation cephalosporin, according to a clinical review article in the February 17 issue of the New England Journal of Medicine.

Study author Michael R. Wessels, MD, from the Division of Infectious Diseases, at the Children's Hospital Boston and Harvard Medical School in Boston, Massachusetts, discusses strategies for treatment and a review of formal guidelines for streptococcal pharyngitis.

According to Dr. Wessels, group A streptococcus (Streptococcus pyogenes) is responsible for 5% to 15% of cases of pharyngitis in adults and 20% to 30% of cases in children.

Streptococcal pharyngitis

The diagnosis of streptococcal pharyngitis should be based on the results of a throat culture or a rapid antigen-detection test of a throat-swab specimen. A rapid antigen-detection test can be used to detect S pyogenes within minutes, but it is less sensitive than culture, "so most guidelines recommend obtaining a throat culture if the rapid antigen-detection test is negative," he notes.

Studies suggest that antibiotic treatment reduces the risk for subsequent development of acute rheumatic fever, acute otitis media, and peritonsillar abscess associated with S pyogenes infection and also the duration of streptococcal symptoms.

Although treatment with antibiotics is recommended, their use has been found to be most cost effective when a rapid antigen-detection test plus culture or a rapid-antigen test alone has been performed. By contrast, empiric antibiotic treatment on the basis of symptoms alone results in "overuse of antibiotics, increased costs, and an increased rate of side effects from antibiotics, as compared with other strategies," the review states.

For treatment, cephalosporins and clindamycin now appear to be more efficacious than penicillin, which may be because of local degradation of penicillin by beta-lactamases produced by throat flora, although penicillin remains the standard of care.

Several guidelines have been issued for the diagnosis and treatment of streptococcal pharyngitis. Specific testing for S pyogenes is not recommended in patients who are not exhibiting any of the 4 clinical features (fever, tender cervical adenopathy, tonsillar or pharyngeal swelling or exudate, and absence of cough).

Guidelines from the American College of Physicians, the American Academy of Family Physicians, and the US Centers for Disease Control and Prevention recommend that adults with 2 or more of the 4 clinical criteria should undergo 1 of 3 approaches: 1) confirmation with a rapid antigen-detection test if 2 criteria are present; 2) treatment in patients who meet all 4 clinical criteria without further testing or who meet 2 or 3 clinical criteria and have a positive result on rapid antigen-detection test; or 3) treatment without testing of patients who meet 3 or 4 clinical criteria.

The Infectious Diseases Society of America and the American Heart Association-American Academy of Pediatrics do not endorse the second and third strategies because of higher rates of unnecessary antibiotic use.

All guidelines recommend the use of penicillin, and the more recently published American Heart Association guidelines also endorse once-daily amoxicillin. Erythromycin is recommended in patients who are allergic to penicillin.

According to Dr. Wessels, "a first-generation cephalosporin is an acceptable alternative unless there is a history of immediate hypersensitivity to a beta-lactam antibiotic."

Dr. Wessels has disclosed no relevant financial relationships.

N Engl J Med. 2011;364:648-655. Extract