title: Detection of a chloramphenicol efflux system in Escherichia coli isolated from poultry carcass.
abstract: An active chloramphenicol efflux system was demonstrated in a multiresistant E. coli isolated from poultry carcass. The effect of different concentrations of chloramphenicol on the original strain and on the plasmid-cured strain was determined in the presence and in the absence of CCCP, an uncoupler of the proton-motive force. Minimal inhibitory concentration (MIC) was lower in the presence of CCCP in the original strain. The plasmid-cured strain displayed lower resistance for chloramphenicol than the wild type, but the MIC was not affected by CCCP. The combined results indicate a plasmid encoded energy dependent resistance mechanism. 3H-chloramphenicol accumulation within the cells was measured by scintillation counting. The uptake or the efflux of 3H-chloramphenicol was influenced by CCCP in the original strain, but not in the plasmid-cured strain. More than one chloramphenicol resistance mechanism may exist in this strain. E. coli is an important commensal or pathogen that inhabits the gastrointestinal tracts of humans and animals, so a plasmid encoded active drug resistance mechanism can be a potential source of horizontal transfer of resistance.
authors.affiliation: Departamento de Veterinária, Universidade Federal de Viçosa, UFV, Campus Universitário, Viçosa, Minas Gerais, CEP 36570-000, Brazil.
authors.forename: M A S
authors.initials: MA
authors.lastname: Moreira
authors.forename: J A
authors.initials: JA
authors.lastname: Oliveira
authors.forename: L M
authors.initials: LM
authors.lastname: Teixeira
authors.forename: C A
authors.initials: CA
authors.lastname: Moraes
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000037:antagonists & inhibitors / Q000493:pharmacokinetics* / Q000494:pharmacology; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000031:analogs & derivatives / Q000494:pharmacology; D002701:Chloramphenicol / Q000037:antagonists & inhibitors / Q000493:pharmacokinetics* / Q000494:pharmacology; D002702:Chloramphenicol Resistance / Q000502:physiology*; D024901:Drug Resistance, Multiple, Bacterial; D004926:Escherichia coli / Q000187:drug effects / Q000302:isolation & purification / Q000378:metabolism*; D004927:Escherichia coli Infections / Q000382:microbiology / Q000662:veterinary*; D007476:Ionophores / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D010957:Plasmids; D011200:Poultry; D011201:Poultry Diseases / Q000382:microbiology*; D018892:Proton-Motive Force / Q000187:drug effects
chemical_list: D000900:Anti-Bacterial Agents; D007476:Ionophores; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D002701:Chloramphenicol