Inducible Erythromycin Resistance of Staphylococcus to Clindamycin

OBJECTIVE To investigate the resistance of Staphylococcus to erythromycin and clindamycin and detect the percentage and gene for inducible resistance in Tai'an.METHODS The susceptibilities of Staphylococcus to erythromycin and clindamycin were examined by Kirby-Bauer disc agar diffusion test and the inducible erythromycin resistance to clindamycin was checked by D-test according to the standards of NCCLS,and the resistance genes msrA,Vgb,sat4,ermA,ermB and ermC were detected by using PCR technology.RESULTS Among the 326 strains,162(44.12%)were all resistant to erythromycin and clindamycin;68(20.86%)were resistant to erythromycin and sensitive to clindamycin but they were positive in D-test;42(12.88%)were resistant to erythromycin and sensitive to clindamycin but they were negative in D-test.The rates of inducible resistance of MRSA,MSSA,MRCNS and MSCNS to clindamycin were 40.00%,56.25%,63.38% and 66.67%,respectively among the Staphylococcus which were resistant to erythromycin and sensitive to clindamycin.The gene ermC was the main one for inducible erythromycin resistance to clindamycin.The percentage of gene ermC was 85.29% and that of ermC and sat4 either was 7.35%;all the others were negative.CONCLUSIONS The rate of inducible erythromycin resistance to clindamycin in our area is relatively high,and D-test in clinical microbiology laboratory should be done so that the physicians can select the reasonable MLSB antimicrobial agents.