Resistance of Staphylococcus and Its Mechanism

OBJECTIVE To investigate the clinical practicability of inducible clindamycin resistance and to evaluate the clinical value of cefoxitin disk diffusion method in detecting the mecA gene of meticillin-resistant Staphylococcus(MRS). METHODS Resistant phenotypes were classified with erythromycin and clindamycin discs using the D test method and the cefoxitin disk diffusion method in detecting mecA gene of the staphylococcus. RESULTS Of all 390 Staphylococcus strains,218 strains(55.9 %) were resistant to erythromycin and clindamycin(cMLS).Seventy strains(17.9 %) which were resistant to erythromycin but susceptible to clindamycin showed the positive D test results(iMLS),79 strains(20.3 %) resistant to erythromycin but susceptible to clindamycin showed the negative D test results(MS).From 390 strains of clinical isolated staphylococcus,which using the cefoxitin disk diffusion method,272 strains were MRS. CONCLUSIONS Using the D test method to investigate the inducible resistance to erythromycin and clindamycin in the Staphylococcus strains,which could help the doctors choose correctly the antibiotics such as macrolides and clindamycin.At the same time,cefoxitin disk diffusion method can be used reliably by the clinical laboratory in detecting and conforming MRS.