摘要
目的研究2株阴沟肠杆菌临床分离株对碳青霉烯类抗生素的耐药机制。方法采用微量肉汤稀释法测定MIC,同时应用K-B法检测对亚胺培南、美罗培南及厄他培南的耐药性,用改良Hodge试验检测碳青霉烯酶;PCR扩增检测碳青霉烯酶(blaKPC、blaIMP-1组、blaIMP-2组、blaVIM)编码基因和广谱及超广谱β-内酰胺酶(blaTEM、blaSHV、blaCTX-M-1组、blaCTX-M-2组、blaCTX-M-9组)编码基因;SDS-PAGE进行细菌外膜蛋白(Omp)分析,并对外膜蛋白基因ompF进行PCR扩增。结果药敏试验显示2株阴沟肠杆菌具有对广谱青霉素、第三、四代头孢菌素、碳青霉烯类、氟喹诺酮类、氨基糖甙类抗生素和酶抑制剂复合制剂的多重耐药性。PCR扩增4种碳青霉烯酶基因和5种广谱及超广谱β-内酰胺酶基因,其中一株阴沟肠杆菌TEM及CTX-M-9组ESBLs基因扩增阳性,其余基因扩增阴性。细菌外膜蛋白SDS-PAGE结果显示:与碳青霉烯类抗生素敏感的阴沟肠杆菌比较,2株碳青霉烯类抗生素耐药的阴沟肠杆菌均缺少分子量在38KDa左右的条带,即OmpF;且PCR扩增其外膜蛋白基因ompF均为阴性。结论 2株阴沟肠杆菌临床分离株对碳青霉烯类抗生素的耐药机制主要与外膜蛋白OmpF的缺失有关。
Objective To investigate the mechanism of two clincal isolates of Enterobacter cloacae resistant to carbopenems. Methods The minimal inhibitive concentrations （MICs） of the antimierobial agents was determined by microdosis broth dilution method. Simultaneously the inhibition zone of imipenem, meropenem, and ertapenem was determined by K-B test. A modified Hodge test may assist in confirming the presence of carbapenemase. The genes coded the β-lactamase were amplified by polymerase chain reaction （PCR）, including carbapenemases（KPC, IMP-1 group, IMP-2 group, VIM）, and broad-spectrum and exceed- broad-spectrum β-lactamases（TEM, SHV, CTX-M-1 group, CTX-M-2 group, CTX-M-9 group）. Outer membrane protein （Omp） was analyzed by sodiumdodecylsulfate- polyacryl amide gel electrophoresis （SDS-PAGE） and the coding gene OmpF was amplified by PCR. Results The susceptibility test showed that the two clincal isolates of Enterobacter cloacae were multi-resistant strains, resistant to broad-spectrum penicillins, third-generation and forth-generation of cephalosporin, earbopenems, fluoroquinolones, aminoglycosides, and β-lactamases inhibitor compounds. Amplifing four carbapenemases genes and five broad- spectrum and exceed-broad-spectrum β-1actamases genes, blaTEM and blacTx.M.9 group ESBLs were positive of one isolate and others were negative. Compared to carbopenem-sensitive isolate by SDS-PAGE, the two carbopenem- resistant isolates markedly lacked the protein band of about 38kDa which might be the outer membrane protein of OmpF, ompF gene was amplified by PCR, the two carbopenem-resistant isolates were all negative. Conclusion Clincal isolates of Enterobacter cloacae resistant to carbopenems might be associated with the loss of outer membrane protein of OmpF.
出处
《中国抗生素杂志》
CAS
CSCD
北大核心
2011年第4期303-306,314,共5页
Chinese Journal of Antibiotics
