铜绿假单胞菌外排泵及整合子与碳青霉烯类耐药中的关系

Interrelationship of outer membrane protein OprM、integron and metallo-β-lactamase among carbapenem resistant Pseudomonas aeruginosa strains

目的明确金属酶、整合子和外排泵在铜绿假单胞菌碳青霉烯类耐药中的作用。方法对42株泛耐药铜绿假单胞菌采用K-B法检测MIC值,双纸片扩散法测金属β-内酰胺酶(MBL),PCR扩增整合子并测序基因盒,real-time PCR检测oprM基因表达,western blot检测外膜蛋白。结果亚胺培南耐药率高达45.23%,美罗培南耐药率71.42%;检出有22株产MBL;Ⅰ类整合子检出率52.30%,携带dhfrⅫ-orfF-aadA2和aacA4-blaVIM-4两种类型的基因盒组合形式;oprM基因高表达细菌是低表达细菌的3.56倍;25株高表达MexAB-OprM外膜蛋白。结论金属酶、整合子均不是铜绿假单胞菌对碳青霉烯类耐药的主要原因,MexAB-OprM高表达致美罗培南耐药。各种耐药机制相互影响,并相互协同。

Objective To identify the role in Pseudomonas aeruginosa isolates. Methods of different resistance mechanism that Forty-two pan-resistant Pseudomonas conferred to carbapenem resistance phenotype aeruginosa were isolated from the Third Xian- gya Hospital. MICs were determined by K B test; double-disk synergy test were used to detect MBL; PCR assays were performed for identification of integron,and variable region were sequenced;quantitative real-time PCR were used to analyze the expression of oprM gene;the expression of outer membrane protein were investigated by Western blot. Results The isolates was highly carbapenem-resistant（MICs of meropenem and imipenem ranged 2 ~ 64 μg/mL and 2 ~ 32 μg/mL, respectively）. 22 strains produced MBL. 22 strains（52.3 % ） contained class 1 integron, harboring variable region ： dhfrXII orfF-aadA2 and aacA4-blaVIM-4. The level of oprM in higher group is 3.56 times of the lower one. The isolates over-expressed efflux pumps MexAB-OprM, Conclusion Overexpression of MexAB-OprM contributes to the meropenem resistance of the strains. The contribution of MBL and integron to earbapenem resistance of Pseudomonas aeruginosa were highly evaluated, however, they have a mutual enhancement for drug-resistance.