碳青霉烯类耐药肠杆菌科细菌碳青霉烯及头孢菌素类抗生素耐药机制

摘要

目的 研究碳青霉烯类耐药肠杆菌科细菌(CRE)对碳青霉烯及头孢菌素类抗生素耐药机制,为临床治疗CRE感染及医院感染的控制提供分子流行病学依据.方法 收集2014-2015年临床送检各类标本分离的细菌,使用Microscan Walkaway 40 plus进行细菌鉴定和药敏试验,对分离的CRE进行常见碳青霉烯酶的编码基因(blaNDM-1及blaKPC-2)和超广谱β-内酰胺酶编码基因(blaTEM、blaSHV、blaCTX-M-1-like、blaCTX-M-2-like、blaCTX-M-8-like及blaCTX-M-9-like)的检测,同时检测细菌多重耐药相关的I类整合子编码基因blainT-1.结果 2014-2015年共分离7株CRE,检出率为0.30%,1~6号菌株为肺炎克雷伯菌,7号菌株为弗劳地柠檬酸杆菌,7株菌株对β-内酰胺酶抑制剂复合制剂、头孢菌素类、头霉素类、碳青霉烯类抗生素均耐药,3株菌对阿米卡星及四环素敏感,2株菌对复方磺胺甲口恶唑敏感.3株菌检出blaNDM-1,2株检出blaKPC-2,5株检出blaTEM,7株均可检出blaSHV,1株检出blaCTX-M-1-like,4株检出blaCTX-M-9-like,5株检出blainT-1,未检出基因blaCTX-M-2-like及blaCTX-M-8-like.结论 blaNDM-1及blaKPC-2是导致7株CRE对碳青霉烯类抗生素耐药的重要机制,blaTEM、blaSHV及blaCTX-M-9-like是导致对头孢菌素类抗生素耐药的主要原因,blainT-1在CRE多重耐药及耐药基因传播中发挥着巨大的作用.%Objective To study the resistance mechanisms of carbapenem-resistant Enterobacteriaceae(CRE) to carbapenems and cephalosporins, and provide molecular evidence for the treatment of CRE infection and control of healthcare-associated infection.Methods Clinically isolated bacteria in 2014-2015 were identified and performed antimicrobial susceptibility testing by MicroScan Walkaway-40 plus system, encoding genes of carbapenems(blaNDM-1 and blaKPC-2) and encoding genes of extended-spectrum β-lactamases (blaTEM, blaSHV, blaCTX-M-1-like, blaCTX-M-2-like, blaCTX-M-8-like, and blaCTX-M-9-like)were detected, multidrug-resistance organism-related class I integron encoding gene blainT-1 was also detected.Results Seven CRE strains were isolated in 2014-2015, isolation rate was 0.30%, strain 1-6 was Klebsiella pneumoniae, strains 7 was Citrobacter freundii, all 7 strains were resistant to β-lactamase inhibitor compound,cephalosporins, cephamicins, and carbapenems,3 strains were sensitive to amikacin and tetracycline, 2 strains were sensitive to compound sulfamethoxazole.3, 2, 5, 7, 1, 4, and 5 strains of CRE were detected carrying blaNDM-1, blaKPC-2, blaTEM, blaSHV,blaCTX-M-1-like, blaCTX-M-9-like,and blainT-1 respectively, no strain was found to carry blaCTX-M-2-like and blaCTX-M-8-like genes.Conclusion blaNDM-1 and blaKPC-2 are important mechanisms leading to carbapenem resistance of 7 CRE strains;blaTEM, blaSHV, and blaCTX-M-9-like are important mechanism leading to cephalosporin resistance, blainT-1 plays an important role in multidrug-resistance to CRE and spread of multidrug-resistant genes.