Contribution of multidrug efflux pumps to multiple antibiotic resistance in veterinary clinical isolates of Pseudomonas aeruginosa

The contribution of efflux pumps to multidrug resistance in 12 Pseudomonas aeruginosa isolates from various animal sources was assessed. Western immun oblot analyses demonstrated that ail twelve isolates expressed significant levels of the MexAB-OprM efflux system whereas two isolates simultaneously expressed the MexEF-OprN or MexXY systems, respectively.. One strain contai ned a single mutation in mexR. a regulator of mexAB oprM expression, that d id not adversely affect the MexR amino acid sequence, and three isolates co ntained the same, single base change in the mexA-mexR intergenic region. Th e MexXY-expressing strain contained two base substitutions in its mex Z reg ulatory gene which did not alter the MexR sequence. (C) 2001 Federation of European Microbiological Societies. published by Elsevier Science B.V. All rights reserved.