大肠埃希菌多重耐药外排泵AcrAB-TolC主动外排机制的研究

Active efflux mechanism of AcrAB-TolC multi-drug efflux pump of Escherichia coli

目的:研究天津地区大肠埃希菌外排泵AcrAB-TolC在临床株中的携带情况、与耐药的相关性及羰基氰氯苯腙(CCCP)对大肠埃希菌外排泵AcrAB-TolC的抑制作用。方法:纸片扩散法(Kirby-Bauer)检测大肠埃希菌临床株对3类6种抗菌药物的敏感性;PCR技术检测受试菌株携带acra、acrb基因的情况;微量肉汤稀释法检测10株多重耐药大肠埃希菌对5种抗菌药物的最低抑菌浓度(MIC),并对比加入CCCP前后MIC的变化。结果:本地大肠埃希菌对6种抗生素均存在不同程度耐药现象,氟喹诺酮类耐药率最高,阿米卡星耐药率最低为10%,耐药模式以双药耐药与多重耐药为主;acra,acrb基因在多重耐药模式中阳性率高达84.6%和80.8%,与全敏感组比较具有统计学差异;加入CCCP后,10株多重耐药菌对5种抗生素的MIC值均有不同程度的下降,最高下降达128倍,多数由耐药变为敏感。结论:本地大肠埃希菌普遍携带外排泵AcrAB-TolC基因,外排泵AcrAB-TolC可能是大肠埃希菌多重耐药的重要原因之一。多重耐药大肠埃希菌存在主动外排机制,CCCP能有效抑制细菌对抗菌药物的主动外排作用。

Objective： To investigate the earring situation of AerAB-TolC efiqux pump of E.eoli detected in clinie in Tianjin, tile correlation with drug resisitanee, and the inhibitory ability of earbonyl cyanide 3-ehloropheny/hydrazone （CCCP） on eMux pump of E.coli. Methods： The suseeptibility of 90 strains orE.coil to 6 antibiotics were deteeted by disk diffusion（Kirby-Bauer）; aera, acrb were deleeted by PCR; The MIC of 10 multi-drug E.coli to 5 antibinties were tested by constant broth dilution method, and compared the variation ot MIC which CCCP has been added. Results： The resissitant to 6 antibiotics exist in varying degrees local E.coli. The resisitant rates of E.coli to fluoroquinotones were the highest, but AMK was the lowest 10%. Two kinds of drug resistance and muhi-drug resisitance were the main parts of resistant patterns. Aera, acrb positive rate were the highest, 84.6% and 80.8%, of multi-drug resistant pattern. After adding CCCP, 10 multi-drug resistant strains of the MICs values of 5 antibioties were tested. The MIC values reduced by 0.78% when compared to the formers tor instance. Most strains turn from drug resistant to sensitive. Conclusion： The earring of aera/aerb ot local E.coli is common. AerAB-TolC is important reason of multi-durg resistance, active efflux mechanism exists in muhi-drug resislaul E. coli. CCCP can inhibit the efflux system of bacteria to antibiotics effetively.