Associations of macrolide and fluoroquinolone resistance with molecular typing in Streptococcus pyogenes from invasive infections, 2010-2012

In this study, the relationship between emm type and antibiotic resistance in 283 invasive group A streptococcal strains collected during surveillance from 2010 to 2012 was analysed. Strains were characterised by emm typing, multilocus sequence typing and antimicrobial susceptibility. Resistance rates for macrolide antibiotics conferred by mef(A), erm(A) or erm(B) were high (54.4%). The most prevalent (40.3%) macrolide resistance mediated by mef(A) was present in 92.2% of emm1 strains. It was found that 53.3% of emm12 strains and 91.7% of emm28 strains had erm(A) or erm(B) genes. Intermediate resistance to fluoroquinolones caused by a mutation in parC was found in 14.1% of strains. Furthermore, three strains (1.1%) with high resistance caused by mutations in both parC and gyrA were detected. Fluoroquinolone resistance was present in various emm types.