Characterisation of the main clones of Streptococcus pyogenes carrying the ermA (subclass TR) gene in Spain

Seventy-four Streptococcus pyogenes isolates showing the macrolide–lincosamide–streptogramin B (MLSB) resistance phenotype carrying the ermA gene (72 of which showed the inducible resistance phenotype) were obtained between 1999 and 2004. Seven different sequence types (STs) and emm types were detected: emm22/ST46 (n = 33); emm77/ST63 (n = 22); emm73/ST331 (n = 10); emm94/ST89 (n = 6); and one isolate each of emm28/ST52, emm11/ST403 and emm4/ST38. All ST46 isolates were susceptible to tetracycline and almost all reacted against the T12 type (all agglutinated into the T-pattern 3/12/13/B3264). Resistance to tetracycline was observed in all ST63 (tetO+) and ST89 (tetM+) isolates. Most of the ST63 isolates reacted against the T28 type (all agglutinated into the T-pattern 9/13/28). The 74 isolates were grouped into eight pulsed-field gel electrophoresis pulsotypes (one cluster for each emm/ST type, except for emm77/ST63).