Genetic characterization of highly fluoroquinolone-resistant clinical Escherichia coli strains from China:: Role of acrR mutations
Genetic characterization of highly fluoroquinolone-resistant clinical Escherichia coli strains from China:: Role of acrR mutations
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DOI：
10.1128/aac.45.5.1515-1521.2001
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发表时间：
2001-05-01
影响因子：
4.9
通讯作者：
Levy, SB
中科院分区：
文献类型：
--
作者：
Wang, H;Dzink-Fox, JL;Levy, SB
中国，对北京地区临床分离的30株耐氟喹诺酮的大肠埃希菌进行了氟喹诺酮类药物耐药的遗传基础研究。每种菌株对其他多种抗生素也表现出抗药性。对拓扑异构酶基因的喹诺酮类耐药决定区(gyrA/B，parc)进行了序列分析，发现3-5个已知突变与氟喹诺酮类药物耐药有关。Western印迹分析未能证明MARA过表达，Northern印迹分析未在任何临床菌株中检测到Soxs RNA的过表达。30株大肠埃希菌中有19株AcrAB多药外排泵AcrA蛋白高表达，且所有菌株均对有机溶剂耐受。对8个分离株的acrR(调节/抑制因子)基因进行PCR扩增，发现4个分离株氨基酸发生改变，另一个9个碱基缺失，6个分离株22个碱基重复，与野生型acrR基因互补使突变株的acrA水平降低1.5-6倍，部分恢复抗生素敏感性。本研究表明acrR基因突变是氟喹诺酮类药物耐药的另一个遗传基础。
The genetic basis for fluoroquinolone resistance was examined in 30 high-level fluoroquinolone-resistant Escherichia coli clinical isolates from Beijing, China. Each strain also demonstrated resistance to a variety of other antibiotics. PCR sequence analysis of the quinolone resistance-determining region of the topoisomerase genes (gyrA/B, parC) revealed three to five mutations known to be associated with fluoroquinolone resistance. Western blot analysis failed to demonstrate overexpression of MarA, and Northern blot analysis did not detect overexpression of soxS RNA in any of the clinical strains. The AcrA protein of the AcrAB multidrug efflux pump was overexpressed in 19 of 30 strains of E, coli tested, and all 19 strains were tolerant to organic solvents. PCR amplification of the complete acrR (regulator/repressor) gene of eight isolates revealed amino acid changes in four isolates, a 9-bp deletion in another, and a 22-bp duplication in a sixth strain, Complementation with a plasmid-borne wild-type acrR gene reduced the level of AcrA in the mutants and partially restored antibiotic susceptibility 1.5- to 6-fold. This study shows that mutations in acrR are an additional genetic basis for fluoroquinolone resistance.