Hansen Lars Hestbjerg, Jensen Lars Bogø, Sørensen Heidi Iskou, Sørensen Søren Johannes
Department of Microbiology, Institute of Biology, University of Copenhagen, Sølvgade 83H, 1307 Copenhagen K, Denmark.
J Antimicrob Chemother. 2007 Jul;60(1):145-7. doi: 10.1093/jac/dkm167. Epub 2007 May 24.
A plasmid-encoded multidrug efflux pump, OqxAB, identified in Escherichia coli of porcine origin, was tested for substrate specificity against selected antibiotics, detergents and disinfectants. The ability of horizontal transfer to food-borne pathogens of the Enterobacteriaceae family was also investigated.
The MICs of selected substrates were determined with a broth dilution assay using two isogenic E. coli strains, except for the presence of the oqxAB operon. A derivative of the plasmid encoding OqxAB (pOLA52) was constructed and horizontal transfer to Salmonella Typhimurium, Klebsiella pneumoniae, Kluyvera sp. and Enterobacter aerogenes was investigated. The effect of the presence of the OqxAB pump on susceptibility for selected compounds was investigated using broth dilution assays.
The OqxAB pump conferred antimicrobial resistance or reduced susceptibility towards a variety of substrates in E. coli. These included animal growth promoters, antimicrobials, disinfectants and detergents. pOLA52 could readily be transferred to enterobacterial pathogens. Transconjugants showed reduced susceptibility towards chloramphenicol, ciprofloxacin and olaquindox.
The plasmid-encoded OqxAB pump has a wide substrate specificity and can be transferred between Enterobacteriaceae conferring reduced susceptibility to a multitude of substrates. These results could indicate some dependence on the outer membrane proteins present in the different species.
对从猪源大肠杆菌中鉴定出的一种质粒编码的多药外排泵OqxAB，针对选定的抗生素、去污剂和消毒剂进行底物特异性测试。还研究了其向肠杆菌科食源性病原体进行水平转移的能力。
使用两种除是否存在oqxAB操纵子外的同基因大肠杆菌菌株，通过肉汤稀释法测定选定底物的最低抑菌浓度（MIC）。构建了编码OqxAB的质粒（pOLA52）的衍生物，并研究了其向鼠伤寒沙门氏菌、肺炎克雷伯菌、克吕韦拉菌属和产气肠杆菌的水平转移。使用肉汤稀释法研究了OqxAB泵的存在对选定化合物敏感性的影响。
OqxAB泵使大肠杆菌对多种底物产生抗药性或敏感性降低。这些底物包括动物生长促进剂、抗菌剂、消毒剂和去污剂。pOLA52能够轻易转移至肠道病原菌。接合子对氯霉素、环丙沙星和喹乙醇的敏感性降低。
质粒编码的OqxAB泵具有广泛的底物特异性，可在肠杆菌科之间转移，导致对多种底物的敏感性降低。这些结果可能表明对不同物种中存在的外膜蛋白存在一定依赖性。
