Resistance and genotypes of erythromycin-resistant Streptococcus pneumoniae isolates

Objective To investigate the prevalence and genotypic characterization of erythromycin-resistant Streptococcus pneumoniae in Shanghai,China.Methods Fifty-seven strains of S.pneumoniae from Zhongshan Hospital were collected to evaluate the prevalence of antibiotic resistance and 53 strains of erythromycin-resistant S.pneumoniae from 4 hospitals in Shanghai were examined by PCR for the presence of macrolide resistance genes(ermB,mefA and mefE).Results Of the 57 isolates,12(21%) were susceptible,3(5.3%) intermediate,and 42(73.7%) resistant to erythromycin.Of the 53 isolates,51(96.2%) were positive for ermB gene,22(41.5%) positive for mefE,and 1(1.9%) positive for mefA gene in PCR study.Both mefE and ermB genes were detected from 21(39.6%) isolates,both mefA and ermB genes were detected in 1 isolate.One isolate had none of mefA,mefE or ermB gene.Conclusions Erythromycin resistance in S.pneumoniae is a serious problem in Shanghai,China.Target alteration induced by ermB is the most common mechanism of erythromycin resistance and mef,especially mefE,is also common in S.pneumoniae isolates from Shanghai.