Contribution of insertion within acrR to acrAB expression and ciprofloxacin resistance in a veterinary Escherichia coli isolate

Abstract

Mutation in acrR would result in enhanced expression of acrAB, increasing fluoroquinolone resistance and partially contributing to the increase in resistance levels to several unrelated antibiotics. An insertion of 777 bp fragment within acrR gene was detected in a clinical E. coli isolates from a diseased duck. In order to determine whether the insertion of acrR was responsible for the elevated expression of acrAB, complementation with wild-type acrR and expression levels of efflux pump and regulator genes by qPCR were carried out. Complementation led to increased sensitivity to ciprofloxacin and to ethidium bromide and decreased expression of acrA and acrB and increased expression of global regulators marA and SoxR compared with that of the parental strains suggesting that the insertion of acrR playing important role in increased acrAB expression and ciprofloxacin resistance. © Medwell Journals, 2012.