title: In vitro susceptibility of Burkholderia vietnamiensis to aminoglycosides.
abstract: Burkholderia cepacia complex (BCC) bacteria are opportunistic pathogens that can cause severe disease in cystic fibrosis (CF) patients and other immunocompromised individuals and are typically multidrug resistant. Here we observed that unlike other BCC species, most environmental and clinical Burkholderia vietnamiensis isolates were intrinsically susceptible to aminoglycosides but not to cationic antimicrobial peptides or polymyxin B. Furthermore, strains acquired aminoglycoside resistance during chronic CF infection, a phenomenon that could be induced under tobramycin or azithromycin pressure in vitro. In comparing susceptible and resistant B. vietnamiensis isolates, no gross differences in lipopolysaccharide structure were observed, all had lipid A-associated 4-amino-4-deoxy-L-arabinose residues, and all were resistant to the permeabilizing effects of aminoglycosides, a measure of drug entry via self-promoted uptake. However, susceptible isolates accumulated 5 to 6 times more gentamicin than a resistant isolate, and aminoglycoside susceptibility increased in the presence of an efflux pump inhibitor. B. vietnamiensis is therefore unusual among BCC bacteria in its susceptibility to aminoglycosides and capacity to acquire resistance. Aminoglycoside resistance appears to be due to decreased cellular accumulation as a result of active efflux.
authors.affiliation: Department of Pathology and Laboratory Medicine, Centre for Understanding and Preventing Infection in Children, University of British Columbia, Room A5-175, Child and Family Research Institute, 950 W. 28th Avenue, Vancouver, British Columbia, V5Z 4H4 Canada.
authors.forename: Agatha N
authors.initials: AN
authors.lastname: Jassem
authors.forename: James E A
authors.initials: JE
authors.lastname: Zlosnik
authors.forename: Deborah A
authors.initials: DA
authors.lastname: Henry
authors.forename: Robert E W
authors.initials: RE
authors.lastname: Hancock
authors.forename: Robert K
authors.initials: RK
authors.lastname: Ernst
authors.forename: David P
authors.initials: DP
authors.lastname: Speert
mesh_terms: D000617:Aminoglycosides / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D019117:Burkholderia / Q000187:drug effects*; D005839:Gentamicins / Q000494:pharmacology; D013058:Mass Spectrometry; D008826:Microbial Sensitivity Tests; D011112:Polymyxin B / Q000494:pharmacology
chemical_list: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D005839:Gentamicins; D011112:Polymyxin B