title: Klebsiella pneumoniae susceptibility to biocides and its association with cepA, qacΔE and qacE efflux pump genes and antibiotic resistance.
abstract: BACKGROUND
  Although antiseptics are some of the most widely used antibacterials in hospitals, there is very little information on reduced susceptibility to these biocides and its relationship with resistance to antibiotics.
  
  
  OBJECTIVE
  To determine the relationship between reduced susceptibility to biocides and the carriage of antiseptic resistance genes, cepA, qacΔE and qacE, as well as identifying the role of efflux pumps in conferring reduced susceptibility.
  
  
  METHODS
  Susceptibility was assessed for five biocides: chlorhexidine, benzalkonium chloride, Trigene, MediHex-4, Mediscrub; and for 11 antibiotics against 64 isolates of Klebsiella pneumoniae. Susceptibility to all compounds was tested by the agar double dilution method (DDM) and the effect of efflux pumps on biocides determined by repeating the susceptibility studies in the presence of the efflux pump inhibitor carbonyl cyanide m-chlorophenyl hydrazone (CCCP). The presence of the cepA, qacΔE and qacE genes was identified by polymerase chain reaction.
  
  
  RESULTS
  The bacteria were not widely antibiotic resistant though a few showed reduced susceptibility to cefoxitin, chloramphenicol and rifampicin and later-generation cephalosporins but not to carbapenems. Biocide susceptibility, tested by DDM, showed that 50, 49 and 53 strains had reduced susceptibility to chlorhexidine, Trigene and benzalkonium chloride, respectively. The antiseptic resistance genes cepA, qacΔE and qacE were found in 56, 34 and one isolates respectively and their effects as efflux pumps were determined by CCCP (10 mg/L), which decreased the minimum inhibitory concentrations (MICs) of chlorhexidine and Medihex-4 by 2-128-fold but had no impact on the MICs of benzalkonium chloride, Trigene and Mediscrub.
  
  
  CONCLUSIONS
  There was a close link between carriage of efflux pump genes, cepA, qacΔE and qacE genes and reduced biocide susceptibility, but not antibiotic resistance, in K. pneumoniae clinical isolates.
authors.affiliation: Molecular Chemotherapy, Centre for Infectious Diseases, University of Edinburgh, Edinburgh, UK.
authors.forename: A
authors.initials: A
authors.lastname: Abuzaid
authors.forename: A
authors.initials: A
authors.lastname: Hamouda
authors.forename: S G B
authors.initials: SG
authors.lastname: Amyes
mesh_terms: D001692:Biological Transport; D004202:Disinfectants / Q000378:metabolism* / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D005798:Genes, Bacterial; D006801:Humans; D007711:Klebsiella pneumoniae / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D008826:Microbial Sensitivity Tests
chemical_list: D004202:Disinfectants; D026901:Membrane Transport Proteins