Detection for inducible clindamycin resistance in erythromycin-resistant isolates of Staphylococcus

Objective To investigate the probability of induction of clindmycin resistance in isolates of Staphylococcus from clinical lab and help clinical physicians to select appropriate therapy decision.Methods K-B disk agar diffusion method was used to test erythromycin or clindamycin resistance in isolates of Staphylococcus,D-test recommended by CLSI/NCCLS was used to examine the inducible resistance of erythromycin to clindamycin.Results The percents of erythromycin-resistant isolates and clindamycin-resistant isolates accounted for 66(49.6%)and 43(33.3%)in 133 tested isolates of Staphylococcus,respectively.And there were 20 inducible clindamycin-resistant isolates(including 10 isolates of S.aureus,9 isolates of S.epidermidis and 1 isolate of S.saprophyticus)whose rate was 30.3% among the 66 erythromycin-resistant isolates.The rates of inducible resistance to clindamycin were 38.5% and 25% in erythromycin-resistant isolates of S.aureus and coagulase-negative Staphylococcus,respectively.There was no induction of clindamycin resistance in isolates with both erythromycin and clindamycin sensitive or clindamycin resistant.Conclusion Erythromycin-resistant and clindamycin-sensitive isolates should be checked by D-test in clinical lab so as to offer physicians correct antimicrobial agents information.