Resistance to macrolides in the species Streptococcus pyogenes in the Czech Republicin 1996–2003

Overview

The study of the prevalence of erythromycin resistance in 22 169 S. pyogenes strains in the CzechRepublic in 1996–2003 on the background of rough data on the nationwide consumption of macrolideantibiotics confirmed that the exponential growth of resistance observed in 1998–2001 copied witha delay the rise in macrolide antibiotic consumption recorded in 1992–1995. The highest frequencyof erythromycin resistance was found in 2001 (16.5 %) with a subsequent decrease to 14.5 % in 2002and to 9.1 % in 2003. The drop in resistance followed the stagnation in macrolide consumption andits decrease by 17 % in 2002. Upward and downward trends in macrolide resistance in differentregions and age groups copied the nationwide trends with some quantitative differences that couldnot be analyzed in view of the lack of detailed data on antibiotic consumption. A 99.5 % concordance was found between the results of the phenotypic method and those of detection of genes coding forconstitutive, inducible and efflux resistance to macrolide-lincosamide-streptograminB (MLSB) antibiotics.In 2001 when the highest erythromycin resistance was recorded in the Czech Republic, mostof the tested strains (91.2 %) showed resistance to all MLSB antibiotics, with macrolide efflux(susceptibility to lincosamides and 16-membered macrolides was conserved) being implicated inresistance of 8.8 % of the strains only. In 2003, the number of erythromycin resistant strainsdecreased and the resistance mechanism was ascribed to macrolide efflux in 26.8 % of them. Almostall of the strains with constitutive or induced MLSB resistance are also resistant to either tetracyclineor bacitracin or both. In the light of S. pyogenes resistance to bacitracin, the bacitracin disk isnot usable in preliminary identification any more.

Key words:
S. pyogenes – macrolide antibiotics – resistance.