MRSA/MSSA对红霉素及克林霉素的诱导耐药性比较研究

Comparative study of inducible resistance to erythromycin and clindamycin of MRSA and MSSA

目的比较医院分离到的耐甲氧西林金黄葡萄球菌(MRSA)和甲氧西林敏感金黄葡萄球菌(MSSA)中诱导型克林霉素耐药的发生率,并比较VITEK COMPAT 2微生物分析系统和双纸片扩散法检测其诱导性的能力。方法对临床分离得到的金黄葡萄球菌进行耐甲氧西林检测,然后用VITEK COMPAT 2微生物分析系统和双纸片扩散法检测其诱导性,并比较检测结果。结果 291例金黄葡萄球菌,MRSA占45.02%(131/291),MSSA占54.98%(160/291),红霉素和克林霉素同时耐药的比例分别为58.02%和36.25%,红霉素和克林霉素同时敏感的比例分别为24.43%和21.88%,erm基因介导诱导型耐药的比例分别为12.98%和38.75%,泵出型耐药比例分别为为4.57%和3.12%。MRSA和MSSA中红霉素耐药克林霉素敏感株诱导率分别为73.91%和92.54%。结论 VITEK COMPAT 2和双纸片法两种方法检测能力无显著差别,均可在临床使用。金黄葡萄球菌红霉素诱导克林霉素耐药问题十分突出,应对红霉素耐药而克林霉素敏感的葡萄球菌进行诱导耐药试验,以保证克林霉素药物敏感试验的准确性。

Objectives To investigate the prevalence of inducible clindamycin resistance in clinical isolates of MRSA and MSSA and to compare VITEK 2 to the double disk diffusion test（D test） in terms of detecting inducible clindamycin resistance in Staphylococcus aurous.Method Bacteria identification and susceptibility testing were performed with the VITEK-2 system.Inducible clindamycin resistance was determined with the VITEK-2 system and compared to results of the D test.Results In 291 cases of S.aureus infection,S.aureus was MRSA in 45.02%（131/291） and MSSA in 54.98%（160/291）.Rates of resistance to erythromycin and clindamycin were 58.02% and 36.25% and rates of susceptibility to erythromycin and clindamycin were 24.43% and 21.88%.The rates of erm gene-mediated inducible resistance were 12.98% and 38.75%.The rates of efflux pump-mediated resistance were 4.57% and 3.12%.Erythromycin-resistant,clindamycin-sensitive MRSA was induced at a rate of 73.91% while erythromycin-resistant,clindamycin-sensitive MSSA was induced at a rate of 92.54%.There were no significant differences in the ability of the D test and VITEK2 to detect inducible resistance.Conclusion Both the D test and microdilution can be used to detect inducible clindamycin resistance in S.aureus.Inducible clindamycin resistance must be detected in clinical laboratories to ensure antimicrobial agents are used properly.