title: Simultaneous overexpression of multidrug efflux pumps in Pseudomonas aeruginosa non-cystic fibrosis clinical isolates.
abstract: The purpose of this study was to examine expression and regulation of 6 multidrug efflux systems, including MexAB-OprM, MexCD-OprJ, MexEF-OprN, MexXY, MexJK, and MexVW, in 13 non-cystic fibrosis (CF) clinical isolates of Pseudomonas aeruginosa. These isolates displayed a high level of resistance to many clinically important antibiotics. Some isolates simultaneously overexpressed up to 4 different Mex systems, as determined by quantitative real-time reverse transcription PCR. None of the isolates overexpressed MexCD-OprJ, and only 1 isolate overproduced MexJK. All the isolates overexpressed MexXY, while overexpression of MexEF-OprN and MexVW was common. DNA sequencing analysis of regulatory genes showed that no clear correlation could be established among (i) the presence of mutations, (ii) the type of mutations, (iii) the expression level of the Mex systems, and (iv) resistance to antibiotic substrates. The results suggest that the concomitant overexpression of some Mex systems may superimpose their antimicrobial drug efflux capabilities, contributing to the multidrug resistance phenotype in the P. aeruginosa non-CF clinical isolates. The existence of uncharacterized regulators for the Mex systems was signified.
authors.affiliation: a Department of Veterinary Public Health, Research Unit in Microbial Food Safety and Antimicrobial Resistance, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand.
authors.forename: Kanchana
authors.initials: K
authors.lastname: Poonsuk
authors.forename: Chanwit
authors.initials: C
authors.lastname: Tribuddharat
authors.forename: Rungtip
authors.initials: R
authors.lastname: Chuanchuen
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D018432:Drug Resistance, Multiple / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D005809:Genes, Regulator / Q000235:genetics*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D011552:Pseudomonas Infections / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D012329:RNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D060888:Real-Time Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
chemical_list: D000900:Anti-Bacterial Agents; D001425:Bacterial Outer Membrane Proteins; D026901:Membrane Transport Proteins; D012329:RNA, Bacterial
keywords: Pseudomonas aeruginosa; multidrug efflux system; multidrug resistance; multirésistance aux médicaments; système d’efflux polychimiothérapeutique