title: Novel role of Acinetobacter baumannii RND efflux transporters in mediating decreased susceptibility to biocides.
abstract: OBJECTIVE
  Biocides and dyes are commonly employed in hospital and laboratory settings. We investigated the biocide susceptibilities of a rapidly emerging pathogen, Acinetobacter baumannii, and the underlying molecular mechanisms, with a primary focus on resistance-nodulation-cell division (RND) efflux systems.
  
  
  METHODS
  Biocide susceptibilities, efflux and in vitro inactivation profiles were monitored in the presence/absence of efflux pump inhibitors. The RND transporters encoded by adeB and adeJ were detected by PCR; null mutants were constructed in the native host. Expression of adeB and adeJ in clinical isolates was assayed by semi-quantitative RT-PCR.
  
  
  RESULTS
  Susceptibility testing and phenotypic assays demonstrated the role of active efflux in mediating decreased susceptibility to biocides. Inactivation of either the adeB or adeJ transporter gene led to increased susceptibility to biocides. RT-PCR analysis exhibited increased adeB and adeJ expression in clinical isolates.
  
  
  CONCLUSIONS
  This is the first study demonstrating the role of efflux pumps in mediating decreased susceptibility to disinfectants and other chemical substrates in A. baumannii.
authors.affiliation: Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, OH, USA.
authors.forename: Govindan
authors.initials: G
authors.lastname: Rajamohan
authors.forename: Vijaya Bharathi
authors.initials: VB
authors.lastname: Srinivasan
authors.forename: Wondwossen A
authors.initials: WA
authors.lastname: Gebreyes
mesh_terms: D040981:Acinetobacter baumannii / Q000187:drug effects* / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D004396:Coloring Agents / Q000494:pharmacology; D004269:DNA, Bacterial / Q000235:genetics; D004202:Disinfectants / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D020869:Gene Expression Profiling; D055786:Gene Knockout Techniques; D006801:Humans; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D008826:Microbial Sensitivity Tests; D016133:Polymerase Chain Reaction / Q000379:methods; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: C445684:AdeB protein, Acinetobacter baumannii; D001426:Bacterial Proteins; D004396:Coloring Agents; D004269:DNA, Bacterial; D004202:Disinfectants; D026901:Membrane Transport Proteins