Evaluation of potential factors contributing to microbiological treatment failure in streptococcus pyogenes pharyngitis

BACKGROUND: A cohort study of children with pharyngitis aged two to 16 years was conducted to assess the role of microbial and host factors in group A beta-hemolytic streptococcus (GABHS) microbiological treatment failure. METHODS: GABHS-infected children had pharyngeal swabs repeated two to five days after completing a 10-day course of penicillin V. M and T typing, and pulsed field gel electrophoresis were performed on the isolates, and the isolates were evaluated for tolerance. Patient characteristics and clinical features were noted and nasopharyngeal swabs for respiratory viruses were taken at enrolment. RESULTS AND CONCLUSIONS: of 286 patients enrolled, 248 (87%) could be evaluated. GABHS was cultured from 104 patients (41.9%), of whom 33 (33.7%) had microbiological treatment failures on follow-up. Although there was a trend toward failure for younger children (mean 6.5±2.4 years versus 7.3±2.4 years, P=O.07) and M type 12 (24%versus 10%, P=0.08), no factors were associated with treatment failure.