Abstract:

Objective To evaluate the drug resistance performance and drug resistance gene on the detection of inducible clindamycin resistance in Staphylococcus by MicroScan Gram-positive composite plate(PC33 composite plate)and D test(erythromycin and clindamycin double-disk diffusion method).Methods The drug resistance of erythromycin/clindamycin composite well of the 115 isolates which were resistant to erythromycin and sensitive to clindamycin by MicroScan automatic ide.pngication was determined. Meanwhile, the inducible resistant phenotype of erythromycin to clindamycin was analyzed by D test, and the resistant gene to macrolide-lincosamide-streptogramin B (MLS) was detected by polymerase chain reaction(PCR). Results The detection rates of PC33 composite plate were 61.3% for Staphylococcus aureus and 47.6% for coagulase-negative Staphylococcus. The detection rates of D test were 61.3% for Staphylococcus aureus and 51.2% for coagulase-negative Staphylococcus. The difference between the 2 methods had no statistical significance(P>0.5). Using D test as a standard to evaluate PC33 composite plate resistant to inducible clidamycin resistance, the sensitivity was 95.1%, and the specificity was 100.0%. The predominant gene for constitutive MLB(cMLS) resistance to clindamycin was ermA. The predominant gene for inducible MLS(iMLS)resistance to clindamycin was ermC. Conclusions The detection results of inducible clindamycin resistance in Staphylococcus by MicroScan Gram-positive composite plate show a coincidence with D test. PC33 composite plate has good clinical significance. The detection of inducible clindamycin resistance should be paid attention in laboratories in order to guide physicians to select antimicrobial agents correctly.

Key words: Inducible clindamycin resistance, Staphylococcus, MicroScan Gram-positive composite plate, D test, Erythromycin, Gene