外排泵adeB基因高表达在鲍氏不动杆菌临床分离株产生泛耐药中的作用

Overexpression of adeB Gene Mediated Multidrug Resistance in Acinetobacter baumannii

目的探讨外排泵adeB基因高表达在鲍氏不动杆菌临床分离株产生泛耐药中的作用。方法 M-H琼脂稀释法检测临床分离的泛耐药鲍氏不动杆菌(PRABA)对常用抗菌药物的最低抑菌浓度(MIC)及羰氰氯苯腙(CCCP)处理前后MIC值的变化情况,聚合酶链反应(PCR)和实时荧光RT-PCR检测泛耐药株adeB基因及adeBmRNA量。结果 PRABA对环丙沙星、四环素、头孢噻肟较CCCP处理前其MIC下降两个折点;头孢西丁下降4个折点,1号与5号菌株庆大霉素下降6个折点,为原MIC值的1/64;10株PRABAadeB基因阳性,2株全敏感鲍氏不动杆菌(PSABA)未检测到adeB基因,PRABAadeB基因mRNA的表达量平均为(0.84E+3)拷贝。结论主动外排泵adeB基因高表达与鲍氏不动杆菌产生泛耐药相关。

OBJECTIVE To study the relationships between the overexpression of efflux pump adeB gene and multiresistance in Acinetobacter baumannii strains from clinical isolates.METHODS M-H agar dilution was used to determine the minimum inhibitory concentrations（MIC） of several classes of antimicrobials against 10 isolates of pandurg-resistant A.baumannii（PRABA） and the change in MIC by carbonyl cyanide m-chlorophenylhydrazone（CCCP）,so as to explore whether the active efflux pumps exist in the isolates of PRABA;polymerase chain reaction（PCR） and real-time fluorescent reverse transcription PCR（qRT-PCR） were used to study the adeB gene encoding and the mRNA expression levels.RESULTS Compared with CCCP treated,at least six breakpoints decrease in MIC was observed in No.1 and 5 isolates for gentamicin,4 breakpoints for cefoxitin,and 2 breakpoint,for ciprofloxacin,tetracycline and cefotaxime,respectively;the adeB gene was detected in all PRABA strains,except for the two pandrug susceptible A.baumannii（PSABA） strains.The levels of mRNA expression of adeB gene were about（0.84E＋3） copies.CONCLUSIONS The multiresistance of A.baumannii is related to the overexpression level of adeB.