title: Expression of resistance-nodulation-cell-division efflux pumps in commonly used Burkholderia pseudomallei strains and clinical isolates from northern Australia.
abstract: Burkholderia pseudomallei is the aetiological agent of melioidosis. Therapy for this disease is lengthy and limited to only a few antibiotics because of this bacterium's intrinsic antibiotic resistance to many clinically useful antibiotics. These properties of B. pseudomallei may partially be due to expression of efflux pumps of the resistance-nodulation-cell-division (RND) family. The patterns and magnitude of RND efflux pump expression in commonly used strains and clinical isolates of B. pseudomallei from the Royal Darwin Hospital, Darwin, Australia, were assessed in cells grown to late exponential phase using quantitative real-time PCR (qRT-PCR). Expression of the three previously identified RND efflux pumps AmrAB-OprA, BpeAB-OprB and BpeEF-OprC, as well as four other yet uncharacterized pumps, was found to be widespread in the clinical isolates. In 45 of 50 isolates (90%), mRNA was detected for at least one of the seven RND pumps. Of these 45 isolates, 41 (82%) expressed multiple pumps with nine strains expressing all seven pumps tested. While these studies revealed no striking correlation between RND efflux pump expression and clinically significant antibiotic resistance, the data support the notion that RND pumps probably play important roles in this bacterium's physiology, defence against toxic compounds, and perhaps virulence.
authors.affiliation: Department of Microbiology, Immunology, and Pathology, Rocky Mountain Regional Center of Excellence for Biodefense and Emerging Infectious Diseases Research, Colorado State University, Fort Collins, CO 80523-2025, USA.
authors.forename: Ayush
authors.initials: A
authors.lastname: Kumar
authors.forename: Mark
authors.initials: M
authors.lastname: Mayo
authors.forename: Lily A
authors.initials: LA
authors.lastname: Trunck
authors.forename: Allen C
authors.initials: AC
authors.lastname: Cheng
authors.forename: Bart J
authors.initials: BJ
authors.lastname: Currie
authors.forename: Herbert P
authors.initials: HP
authors.lastname: Schweizer
mesh_terms: D001315:Australia; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics*; D016957:Burkholderia pseudomallei / Q000187:drug effects / Q000235:genetics*; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D006801:Humans; D008826:Microbial Sensitivity Tests; D009876:Operon / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D001425:Bacterial Outer Membrane Proteins; D037521:Virulence Factors