Culture and antigen detection tests for streptococcal tonsillopharyngitis.

A throat culture is necessary for accurate diagnosis of group A beta-hemolytic streptococcal tonsillopharyngitis. The use of penicillin therapy in every patient with sore throat results in overtreatment of 85 percent of children and 95 percent of adults presenting to family physicians with the complaint of sore throat. Indiscriminate use of penicillin also increases the risk of drug side effects and subjects some patients to unnecessary alterations of microbial ecology. The signs and symptoms of group A beta-hemolytic streptococcal tonsillopharyngitis are nonspecific, and reliable clinical diagnosis is difficult. Throat culture is cost-effective and, if properly obtained and processed, more than 95 percent accurate. Antigen detection tests (rapid strep tests) are a viable laboratory alternative to throat cultures if these tests are properly performed and if negative test results are confirmed with traditional throat culture.