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An unusual emm53, T-28/T-non-typeable, iMLS(B) phenotype clone represented a substantial proportion (28.6%) of invasive erythromycin-resistant group A streptococcus (GAS) isolates in the Czech Republic during 2003. Clonal analysis of emm53 isolates between 2001 and 2004 revealed four pulsed-field gel electrophoresis (PFGE) patterns and two emm subtypes. Isolates produced identical PFGE patterns regardless of their invasiveness and/or tetracycline resistance. Multilocus sequence typing classified all isolates as ST340. An ST5 (emm83) isolate, a potential ancestor of ST340, was isolated in the Czech Republic from an impetigo patient in 1988. The Czech emm53/ST340 isolates shared only three of seven alleles with the original Lancefield emm53/ST11 isolate.

In total, 1039 pediatric Streptococcus pyogenes isolates from Bulgaria, Croatia, the Czech Republic, Hungary, Latvia, Lithuania, Poland, Romania, Slovakia and Slovenia were studied. All strains were susceptible to penicillin G, levofloxacin, and quinupristin–dalfopristin, 91–100% to telithromycin, and 82–100% to erythromycin, azithromycin, and clarithromycin, and 90–100% to clindamycin. Macrolide resistance occurred mainly in Slovakia (25%), the Czech Republic (17.3%), and Croatia (15.8%). Overall, 9.7% of S. pyogenes isolates were erythromycin resistant due to erm(B) - or erm(A) -encoded methylases (72.3%) or to a mef(A) -encoded efflux pump (25.7%). One strain had alterations of both 23S rRNA (A2058G Escherichia coli numbering) and ribosomal protein L22 (G95D). [ABSTRACT FROM AUTHOR]