Prevalence and molecular mechanism of macrolide resistance in beta-haemolytic streptococci in The Netherlands.

The prevalence of resistance to erythromycin and clindamycin as well as the presence of the resistance genes mef(A), mef(E), erm(A) and erm(B) were determined in 1076 consecutive isolates of beta-haemolytic streptococci of Lancefield groups A (n=219), B (n=562),C (n=58) and G (n=237) collected during 2005 and 2006. The prevalence of macrolide resistance was highest in group C streptococci (6.9%), followed by group B (5.3%), group G (4.6%) and group A (1.4%). Eighty-eight percent of resistance was mediated by erm(A) and erm(B) genes. Macrolide resistance in beta-haemolytic streptococci in The Netherlands is low, but increasing macrolide resistance was observed in group B streptococci.