Macrolide-resistant Streptococcus pneumoniae in Canada during 1998-1999: prevalence of mef(A) and erm(B) and susceptibilities to ketolides.

In this study (1998-1999), we collected 215 macrolide-resistant Streptococcus pneumoniae isolates from an ongoing Canadian Respiratory Organism Surveillance Study involving 23 centers representing all regions of Canada. The prevalence of erythromycin-resistant S. pneumoniae was 8% (215 of 2,688). Of the 215 isolates, 48.8% (105 of 215) were PCR positive for mef(A) and 46.5% (100 of 215) were PCR positive for erm(B). The ketolides telithromycin and ABT-773 demonstrated excellent activity against both mef(A) (MIC for 90% of strains [MIC(90)], 0.06 and 0.03 microg/ml, respectively) and erm(B) (MIC(90), 0.06 and 0.03 microg/ml, respectively) strains of S. pneumoniae.