Antimicrobial susceptibility and macrolide resistance genes in Streptococcus pyogenes collected in Austria and Hungary

Abstract A total of 341 clinical isolates of Streptococcus pyogenes from Vienna, Austria and three Hungarian cities were tested for susceptibility to four macrolides and 12 other antibiotics. All isolates were fully susceptible to penicillin and the other β-lactams tested. A high level of tetracycline resistance was found in Austria (26.7%) and in Hungary (30.5%). The rate of resistance to erythromycin, clarithromycin and azithromycin was 4.7% in Vienna and 3.7% in the Hungarian communities. In both countries, the MIC 90 values of erythromycin and clarithromycin were 0.12 mg/L and the MIC 90 of josamycin was 0.5 mg/L. The M phenotype of resistance conferred by the mef A genes was predominant ( n =9) among the macrolide-resistant isolates ( n =14).