title: Competition between substrates of the efflux pump system of Salmonella enteritidis.
abstract: OBJECTIVE
  To determine whether tetracycline competes with ethidium bromide (EB), used as substrate of efflux pumps, for extrusion by the efflux pump system of Salmonella enteritidis NCTC 13349 reference strain.
  
  
  METHODS
  Evaluation of efflux of EB in competition with tetracycline was conducted with the aid of an automated EB method and by EB agar method.
  
  
  RESULTS
  The EB agar method demonstrated that the accumulation of EB by S. enteritidis NCTC 13349 reference strain is reduced by high concentrations of tetracycline and that tetracycline accumulates within the cells. The use of the automated EB method confirmed the EB agar results and demonstrated that accumulation of EB is not affected by tetracycline unless the concentration of the antibiotic exceeds 100 mg/l.
  
  
  CONCLUSIONS
  These results suggest that tetracycline is preferentially retained and that EB is preferentially extruded by the efflux pump of Sientintidis NCTC 13349.
authors.affiliation: Grupo de Micobacterias, Unidade de Microbiologia Médica, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Lisboa, Portugal.
authors.forename: Pedro
authors.initials: P
authors.lastname: Cerca
authors.forename: Ana
authors.initials: A
authors.lastname: Martins
authors.forename: Isabel
authors.initials: I
authors.lastname: Couto
authors.forename: Miguel
authors.initials: M
authors.lastname: Viveiros
authors.forename: Leonard
authors.initials: L
authors.lastname: Amaral
mesh_terms: D000900:Anti-Bacterial Agents / Q000378:metabolism / Q000494:pharmacology; D001426:Bacterial Proteins / Q000378:metabolism*; D001692:Biological Transport; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D024901:Drug Resistance, Multiple, Bacterial / Q000187:drug effects; D004996:Ethidium / Q000378:metabolism* / Q000494:pharmacology; D005947:Glucose / Q000494:pharmacology; D026901:Membrane Transport Proteins / Q000378:metabolism*; D054328:Proton Pump Inhibitors / Q000494:pharmacology; D012477:Salmonella enteritidis / Q000187:drug effects / Q000378:metabolism*; D013752:Tetracycline / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D026901:Membrane Transport Proteins; D054328:Proton Pump Inhibitors; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D004996:Ethidium; D013752:Tetracycline; D005947:Glucose