In vitro susceptibility of Streptococcus pyogenes strains recently isolated from pharyngotonsillitis in France

Between November 1995 and May 1996, 173 French general practitioners conducted an epidemiologic survey to evaluate the susceptibility of Streptococcus pyogenes isolated from acute pharyngotonsillitis. 2800 adults and children over 4 years of age were enrolled. Among them, 393 had positive rapid strep tests (Testpack plus Strep A(R), Abbott), 375 underwent bacteriological sample for culture. 324 Streptococcus pyogenes were isolated and the predictive positive value of the test was 86.4 %. The minimum inhibitory concentrations (MIC) of several oral antibiotics were determined by the agar dilution method. All 324 strains were susceptible to penicillin, ampicillin, cefaclor (concentration of antibiotic required to inhibit 90 % of isolates, respectively, 0.016, 0.032, 0.5 mu gr/ml). For erythromycin, 94.5 % (306/324) of tested strains were susceptible, 18 had MIC of 2 mu gr/ml or greater (MIC between 2 and 4 mu gr/ml for 10 isolates and MIC greater than or equal to 8 mu gr/ml for 8 isolates).