Resistance to macrolides in Streptococcus pyogenes in France in pediatric patients

A total of 1,500 recent throat isolates of Streptococcus pyogenes collected between 1996 and 1999 from children throughout France were tested for thei r susceptibility to erythromycin, azithromycin, josamycin, clindamycin, and streptogramin B, The erythromycin-resistant isolates mere further studied for their genetic mechanism of resistance, by means of PCR, The clonality o f these strains was also investigated by means of serotyping and ribotyping , In all, 6.2% of the strains were erythromycin resistant, and 3.4 and 2.8% expressed the constitutive MLSB and M resistance phenotypes and harbored t he ermB and mefA genes, respectively; ermTR was recovered from one isolate which also harbored the ermB gene. Ten serotypes and 8 ribotypes were ident ified, but we identified 17 strains by combining serotyping with ribotyping , Among the eight ribotypes, the mefA gene was recovered from six clusters, one being predominant, while the ermB gene was recovered from four cluster s, of which two were predominant.