[抗生素主动外排作为大肠杆菌临床菌株多重耐药机制的研究]
[Active efflux of antibiotics as multiple-antibiotic-resistance mechanism in clinical strains of escherichia coli].
作者信息
Zhang X, Li J
机构信息
Institute of Clinical Pharmacology, First Affiliated Hospital of Beijing Medical University, Beijing 100083, China.
出版信息
Zhonghua Yi Xue Za Zhi. 2000 Aug;80(8):614-7.
OBJECTIVE
To investigate multiple-antibiotic-resistance mechanism in clinical strains of Escherichia coli.
METHODS
Accumulation of ciprofloxacin in clinical isolates of Escherichia coli was measured by fluorometry, and acrAB gene was identified by PCR and Southern blot. The levels of acrAB gene expression were measured by RT-PCR. DNA fragments were sequenced by automated fluorescence sequencing.
RESULTS
The state concentration of ciprofloxacin in multiple-antibiotic-resistant (Mar) strains was significantly lower than that in susceptible stsains (0.73 mg/L +/- 0.04 mg/L vs 2.00 mg/L +/- 0.07 mg/L A(660), P < 0.001). The level of acrAB gene expression in Mar strains was significantly higher than that in other strains. No deletion or point mutation in acrAB gene were found in Mar and susceptible clinical Escherichia coli isolates.
CONCLUSIONS
High expression of acrAB gene leads to multiple-antibiotic-resistance in clinical strains of Escherichia coli, and Mar operon may contribute to the regulation of acrAB gene expression.
目的
研究临床分离的大肠杆菌多重耐药机制。
方法
采用荧光法测定临床分离的大肠杆菌中环丙沙星的蓄积量，通过聚合酶链反应（PCR）和Southern印迹法鉴定acrAB基因。采用逆转录聚合酶链反应（RT-PCR）测定acrAB基因的表达水平。通过自动荧光测序对DNA片段进行测序。
结果
多重耐药（Mar）菌株中环丙沙星的稳态浓度显著低于敏感菌株（0.73 mg/L±0.04 mg/L对2.00 mg/L±0.07 mg/L A(660)，P<0.001）。Mar菌株中acrAB基因的表达水平显著高于其他菌株。在Mar和敏感的临床大肠杆菌分离株中未发现acrAB基因的缺失或点突变。
结论
acrAB基因的高表达导致临床分离的大肠杆菌产生多重耐药，Mar操纵子可能参与acrAB基因表达的调控。
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