RESUMEN
OBJECTIVE To investigate the antimicrobial susceptibility of Streptococcus pneumoniae isolated in Yantai and their mechanisms of resistance to macrolides.METHODS Antimicrobial susceptibility of S.pneumoniae was determined by agar dilution method.Phenotypes of macrolide-resistant S.pneumoniae were determined using double disk test with erythromycin and clindamycin disks.ermB And mefE genes were amplified by PCR.RESULTS Among 42 strains of S.pneumoniae,65.0% were intermediate to and no strain was resistant to penicillin.The resistance rates to erythromycin and clindamycin were 93.0%,respectively.Of 41 erythromycin resistantstrains,93.0% were constitutive resistant.ermB Was detected in 40 strains and mefE in 1 strain,both ermB and mefE genes were found in 9 strains.CONCLUSIONS The resistance rate of S.pneumoniae to penicillin is high in Yantai area,the resistance rates to erythromycin and clindamycin are very high.Target modification by ermB methylase is the predominant mechanism in macrolide-resistant S.pneumoniae in Yantai.