Polyclonal dissemination of tetracycline resistance among Streptococcus pyogenes paediatric isolates from Brazil.

INTRODUCTION Scarce data are available on Group A Streptococcus (GAS) antibiotic resistance in South America. METHODOLOGY The antibiotic susceptibility patterns of GAS recovered from symptomatic children living in the central part of Brazil during a prospective epidemiological study were analyzed. RESULTS No isolates were resistant to penicillin or macrolides.  Sixty-one percent of the isolates were highly resistant to tetracycline, of which 85% harboured the tetM resistance gene. Ninety-five percent of these tetracycline resistant isolates were also resistant to minocycline. Thirty different emm-types were associated with tetracycline resistance. Phylogenetic analysis indicates that tetracycline resistance arose independently in distantly related emm-types. CONCLUSIONS A high level of GAS tetracycline resistance has been observed in the central part of Brazil due to the polyclonal dissemination of resistant emm-types.