The increase in erythromycin resistance among Streptococcus pyogenes isolates is a cause for concern. We analysed trends in macrolide resistance, phenotypes, genotypes, resistance determinants and transposons among erythromycin-resistant S. Antibiotic susceptibility was studied by microdilution. Macrolide resistance genes and those related to the Tn family of transposons were detected by PCR. Sixty-six erythromycin-resistant isolates were available for molecular studies.
Among M-phenotype isolates, the most frequent genotypes Twenty-five isolates harboured both erm B and tet M genes related to the Tn family of transposons, Tn being the most frequent. The peak of macrolide resistance rates among S.
However, erythromycin resistance rates decreased significantly in the โ period. Streptococcus pyogenes is an important human pathogen which causes a wide variety of invasive and non-invasive infections including pharyngo-tonsillitis, skin and soft tissue infections, pneumonia and bacteraemia. Group A streptococci GAS produce virulence determinants such as the Spe family of exotoxins, which play an important role in colonization, dissemination, systemic toxicity and tissue damage.
Penicillin is the treatment of choice in GAS infections. In recent years, increasing rates of macrolide resistance among S. The first is target site modification by methylases encoded by the erm B gene or erm TR [of the erm A class] related to the MLS B phenotype resistance to macrolideโlincosamideโstreptogramin B.
The second mechanism is an efflux pump encoded by the mef A gene and related to the M phenotype resistance to and membered ring macrolides. The aim of this study was to investigate the epidemiology of macrolide-resistant S.
