Inducible Resistance of Erythromycin to Clindamycin and Resistance Genes in Staphylococcus

OBJECTIVE To detect the resistance of Staphylococcus to erythromycin and clindamycin,and analyze the prevalence of inducible resistance of erythromycin to clindamycin and resistance gene in Staphylococcus. METHODS The susceptibilities to erythromycin and clindamycin for Staphylococcus were examined by Kirby-Bauer disc agar diffusion test and the inducible resistance of erythromycin to clindamycin was checked by D-test according to the standards of NCCLS(2004,M100-S14).msrA,Vgb,sat4,ermA,ermB And ermC resistance genes were detected by using PCR technology. RESULTS Co-resistance to erythromycin and clindamycin accounted for 80.00% and 54.17% in MRSA and MRCNS,respectively. The rate of D-test positive was 26.15% among all Staphylococcus tested,and it was 68.00% among the erythromycin resistant and clindamycin sensitive Staphylococcus.The D-test positive rate of inducible resistance to clindamycin was 75.00% and 65.88% in Staphylococcus aureus and coagulase-negative Staphylococcus which were erythromycin resistant and clindamycin sensitive by individual disk diffusion test.The ermC gene was the main one for inducible resistance of erythromycin to clindamycin.The percentage of ermC gene was 76.47% and that of ermC+sat4 was 8.82%. CONCLUSIONS The inducible resistance of erythromycin to clindamycin in Staphylococcus should be detected by D-test in clinical microbiology laboratory in order to guide physicians to select reasonable antibiotics for Staphylococcus infection.