[Sore throat. Rapid detection of beta hemolytic group A streptococci by a coagglutination method].

In Norway anually half a million consultations are for acute sore throat. The clinical differentiation between streptococcal and non-streptococcal infection remains poor. A reliable diagnosis of beta-hemolytic streptococcal infections requires a screening test. In a multicenter study from general practice the rapid test Phadirect Strep A was compared with cultivation at two microbiological laboratories. 257 patients were included and the prevalence of beta-hemolytic streptococci was 41.6%. The results of valid calculations were: Sensitivity 70-77%; Specificity 86-89%; Positive predictive value 74-82%; Negative predictive value 81-88%. The results were considered in relation to body temperature and signs of local infection in the throat. There was no correlation between clinical signs and occurrence of beta-hemolytic streptococci. The Phadirect Strep A test was acceptably sensitive and specific for use in general practice. The test is easy to perform, and the results are available after five minutes. The test seems to be useful, and is an improvement in the daily management of patients with acute throat infections, especially in relation to the question of whether or not to prescribe antibiotics.