碳青霉烯耐药肠杆菌科细菌的耐药机制探讨

Resistance mechanism of carbapenem resistance in Enterobacteriaceae

目的探讨本院存在的碳青霉烯类耐药肠杆菌科细菌的耐药机制。方法临床检出碳青霉烯类抗菌药物非敏感肠杆菌科细菌6株。改良Hodge实验、EDTA协同试验检、改良三维实验检测其耐药表型;引物特异性PCR法检测其碳青霉烯酶耐药基因及外膜蛋白基因存在情况。结果 1株大肠埃希菌中改良Hodge实验弱阳性,EDTA协同试验阳性,改良三维实验结果可被CLA单独抑制,PCR扩增结果IMP4碳青霉烯酶基因阳性。5株产气肠杆菌改良Hodge实验,阴性3株,阳性两株,EDTA协同试验阴性;改良三维实验中,5株均可被CLO+CLA混合液完全抑制,PCR未扩增出目的基因条带和膜蛋白基因。结论本地区大肠埃希菌的耐药机制可能与IMP4型金属碳青霉烯酶存在有关,产气肠杆菌耐药机制可能与ESBLs和AmpC酶同时存在、膜蛋白表达缺失及其他未检测到的碳青霉稀酶存在有关。

Objective To investigate the mechanism of Enterobacteriaceae resistanct to carbapenem isolated in this hospital. Methods 6 strains of carbapenem antibacterial drug non-sensitive Enterobacteriaceae bacteria were determined. Modified Hodge test, EDTA synergy test and improved three-dimension test were used to detect the presence; polymerase chain reaction （PCR） to detect genes of the carbapenemases and outer membrane protein. Results The Escherichia coli modified Hodge test was weak positive, EDTA synergy test was positive, improved three-dimension test resulted by CLA alone inhibit. The PCR amplification resulted IMP4 gene were positive. 5 isolates of Enterobacter aerogenes modified Hodge test were positive of two isolates, EDTA synergy test was negative. In the improved three-dimension test, all of the five can be completely inhibited by the CLOs ＋ the CLA mixture. The strip of target gene and membrane protein gene was not amplified in PCR. Conclusion The resistance mechanisms of E. coli from this region may be related to the IMP4 metal carbapenemase. And, the resistant mechanism of Enterobacter aerogenes might associate with the existing of ESBLs and AmpC enzymes at the same time and the missing of outer membrane negative.