title: Mechanisms of resistance in Salmonella enterica adapted to erythromycin, benzalkonium chloride and triclosan.
abstract: The potential for adaptive resistance of S. enterica serovar Enteritidis, Typhimurium and Virchow to increasing sub-lethal concentrations of erythromycin, benzalkonium chloride and triclosan was investigated to identify mechanisms underlying resistance. Permeability changes of the outer membrane, including LPS, cell surface charge, hydrophobicity and the presence of an active efflux in the adapted strain compared with the parent were studied. Examination of the outer membrane and LPS did not reveal any significant changes, although most of the pre-adapted strains were notably less hydrophobic than resistant strains. More than one type of active efflux was identified in all strains investigated, on the basis of restored sensitivity in the presence of the inhibitors reserpine and carbonyl cyanide 3-chlorophenylhydrazone (CCCP). Cell surface hydrophobicity and the presence of active efflux could contribute to the resistance of S. enterica to the antibacterial agents studied here.
authors.affiliation: Microbiology, School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK.
authors.forename: Maria
authors.initials: M
authors.lastname: Braoudaki
authors.forename: Anthony C
authors.initials: AC
authors.lastname: Hilton
mesh_terms: D000222:Adaptation, Physiological; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000891:Anti-Infective Agents, Local / Q000494:pharmacology*; D001548:Benzalkonium Compounds / Q000494:pharmacology; D001693:Biological Transport, Active; D002463:Cell Membrane Permeability; D024881:Drug Resistance, Bacterial; D004917:Erythromycin / Q000494:pharmacology; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008826:Microbial Sensitivity Tests; D019779:Salmonella enterica / Q000145:classification / Q000187:drug effects* / Q000502:physiology; D012477:Salmonella enteritidis / Q000187:drug effects / Q000502:physiology; D012486:Salmonella typhimurium / Q000187:drug effects / Q000502:physiology; D014260:Triclosan / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D000891:Anti-Infective Agents, Local; D001548:Benzalkonium Compounds; D014260:Triclosan; D004917:Erythromycin