耐碳青霉烯类肠杆菌科细菌耐药机制的研究

Drug resistance mechanisms of carbapenem-resistant Enterobacteriaceae strains

目的 研究耐碳青霉烯类肠杆菌科细菌（CRE）的耐药机制,为临床合理使用抗菌药物提供依据。方法 连续收集某院2011年1月-12月临床分离菌中非重复的肠杆菌科细菌2 203株,VITEK-2全自动微生物分析系统对其进行鉴定及药敏试验;改良Hodge试验初筛碳青霉烯酶;EDTA-亚胺培南（IPM）协同法和亚胺培南双纸片增效法确认金属酶表型;PCR法检测β-内酰胺酶基因及整合子基因,产物测序,BLAST软件比对分析。结果 2 203株肠杆菌科细菌中共检出17株CRE,检出率为0.7%;药敏结果显示,17株CRE菌株对常用抗菌药物高度耐药,除对阿米卡星和头孢哌酮/舒巴坦的耐药率低,分别为35.3%和47.1%,对其他抗菌药物的耐药率在76.4%~100.0%;17株菌均检出blaTEM基因,6株肺炎克雷伯菌同时检出blaSHV基因,并且其中1株肺炎克雷伯菌同时携带blaKPC-2基因,其余基因均阴性;3种整合子中intⅠ基因为阳性,检出率高达70.6%。结论 携带blaTEM、blaSHV和blaKPC-2基因是导致该院肠杆菌科细菌对碳青霉烯类抗菌药物耐药的重要原因,Ⅰ类整合子在其耐药基因的转移方面起了十分重要的作用。

OBJECTIVE To explore the drug resistance mechanisms of carbapenem-resistant Enterobacteriaceae （CRE） strains so as to provide guidance for reasonable clinical use of antibiotics. METHODS A total of 2 203 clinical non-fermenting Enterobacteriaceae isolates were successively collected from Jan 2011 to Dec 2011, then the strains were identified by using VITEK-2 automatic microorganism analysis system, the drug susceptibility testing was carried out, the carbapenemases were primarily screened by modified Hodge test, the metalloenzymes were primarily screened by means of EDTA-imipenem synergistic method and imipenem double disk synergy method, the/3-lactamase genes and integron genes were detected with the use of PCR method, the products were se- quenced, and the comparative analysis was performed by using BLAST software. RESULTS Totally 17 strains of CRE were screened out from the 2 203 strains of Enterobacteriaceae, with the detection rate 0.7 %. The drug sus- ceptibility testing results showed that the 17 strains of CRE were highly resistant to the commonly used antibiot- ics, the drug resistance rates to amikacin and cefoperazone-sulbactam were 35.3 % and 47.1%, respectively, the drug resistance rate to other antibiotics varied from 76.4% to 100.0%. The blaTEM was detected in 17 strains, the blasHv was detected in 6 strains of Klebsiella pneumoniae, the blaKPC-2 was detected in 1 strain of K. pneumoniae, and the rest of genes were detected negative. The int I was tested positive in the 3 types of integrons, with the detection rate 70.6%. CONCLUSION The Enterobacteriaceae strains carrying with the blaTEM, blasHv and blaKPC-2 genes are the leading causes of the resistance to carbapenems antibiotics, and the type I integron plays a very im- portant role in transmission of the drug resistance genes.