摘要
目的:研究临床分离多重耐药肺炎克雷伯菌的耐药机制,检测肺炎克雷伯菌中有无类似大肠埃希菌主动外排系统AcrAB的结构基因acrAB的分布和表达。方法:用聚合酶链反应(PCR)检测acrAB基因在临床分离的肺炎克雷伯菌和肺炎克雷伯菌标准菌株(ATCC 10031)中分布,用逆转录(RT)-PCR测定其 mRNA表达水平,并对 PCR扩增的 ATCC 10031的acsAB基因片段进行序列分析,同大肠埃希菌acrAB基因的相应序列进行同源性比较。结果:在所有被检的临床分离肺炎克雷伯菌和 ATCC 10031的染色体中均发现有类似大肠埃希菌的 acrAB基因;肺炎克雷伯菌多重耐药菌株 acrAB的 mRNA水平显著高于敏感野生株和耐药谱不同的菌株,而耐药谱不同的菌株仅略高于敏感菌株;PCR扩增的 ATCC 10031的 acrAB基因片段同大肠埃希菌acrAB基因相应片段,在核苷 序列上具有很高的同源性。结论:本研究表明在肺炎克雷伯菌中有类似大肠埃希菌的acrAB基因存在,其表达水平决定了多重耐药表型。
To study the mechanism of multidrug resistance in c1inical isolates of Klebsiella pneumoniae and detect the dis-tribution and expression of active efflux pump gene acrAB, homologous to that in Escherichia coli. Methods: The distribution ofacrAB in clinical strains and the standard strain (ATCC 10031) of Klebsiella pneumoniae was determined by PCR, and the 1evel ofmRNA expressions of acrAB by RT-PCR. We also analyzed the nucleotide sequence of acrAB section amplified by PCR in K. pneu-moniae ATCC 10031, and compared with the corresponding sequence of acrAB gene in Escherchia coli. Results: arcAB gene ho-mologous to that in Escherichia coli was found in all clinical strains of K. Pneumoniae and ATCC 10031. The levels of mRNA ex-pression of acrAB in multidrug-resistant (MDR) strains were significant1y higher than those in wild susceptible strains and in strainswith different resistance patterns(P < 0.01 ). But those in strains with different resistance patterns were only a little higher thanthose in wild susceptible strains (P< 0.05). There was high degree of homology in nucleotide sequence between the PCR expandedATCC 10031 acrAB gene sections and the corresponding ones in Escherichia coli. Conclusions: The study indicates that acrAB genehomologous to that in Escherchia coli is present in Klebsiellla pneumoniae, and its level of expression determines the multiple-resis-tant phenotype of the bacteria.
出处
《中国抗感染化疗杂志》
2001年第4期193-197,共5页
Chinese Journal of Infection and Chemotherapy
