title: Detection of multiple-antimicrobial resistance and characterization of the implicated genes in Escherichia coli isolates from foods of animal origin in Tunis.
abstract: Phenotypic and genotypic characterization of antimicrobial resistance was conducted for 98 Escherichia coli isolates recovered from 40 food samples of animal origin (poultry, sheep, beef, fish, and others) obtained in supermarkets and local butcheries in Tunis during 2004 and 2005. Susceptibility to 15 antimicrobial agents was tested by disk diffusion and agar dilution methods, the mechanisms of resistance were evaluated using PCR and sequencing methods, and the clonal relationship among isolates was evaluated using pulsed-field gel electrophoresis. High resistance was detected to tetracycline, sulphonamides, nalidixic acid, ampicillin, streptomycin, and trimethoprim-sulfamethoxazole (29 to 43% of isolates), but all isolates were susceptible to cefotaxime, ceftazidime, cefoxitin, azthreonam, and amikacin. One-third of the isolates had multiresistant phenotypes (resistance to at least five different families of antimicrobial agents). Different variants of blaTEM, tet, sul, dfrA, aadA, and aac(3) genes were detected in most of the strains resistant to ampicillin, tetracycline, sulphonamide, trimethoprim, streptomycin, and gentamicin, respectively. The presence of class 1 and class 2 integrons was studied in 15 sulphonamide-resistant unrelated E. coli strains, and 14 of these strains harbored class 1 integrons with five different arrangements of gene cassettes, and a class 2 integron with the dfrA 1 + sat + aadA 1 arrangement was found in one strain. This study revealed the high diversity of antimicrobial resistance genes, some of them included in integrons, in E. coli isolates of food origin.
authors.affiliation: Laboratoire MBA, Départements de Biologie, Faculté de Sciences de Tunis, Campus Universitaire, 2092 Tunis, Tunisia.
authors.forename: Ahlem
authors.initials: A
authors.lastname: Jouini
authors.forename: Karim
authors.initials: K
authors.lastname: Ben Slama
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Sáenz
authors.forename: Naouel
authors.initials: N
authors.lastname: Klibi
authors.forename: Daniela
authors.initials: D
authors.lastname: Costa
authors.forename: Laura
authors.initials: L
authors.lastname: Vinué
authors.forename: Myriam
authors.initials: M
authors.lastname: Zarazaga
authors.forename: Abdellatif
authors.initials: A
authors.lastname: Boudabous
authors.forename: Carmen
authors.initials: C
authors.lastname: Torres
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015169:Colony Count, Microbial; D004269:DNA, Bacterial / Q000032:analysis; D004305:Dose-Response Relationship, Drug; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D004926:Escherichia coli / Q000145:classification / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D005504:Food Analysis; D005506:Food Contamination / Q000032:analysis*; D005516:Food Microbiology; D005798:Genes, Bacterial; D005838:Genotype; D032023:Integrons; D008461:Meat Products / Q000382:microbiology*; D008826:Microbial Sensitivity Tests; D010641:Phenotype; D010802:Phylogeny; D014416:Tunisia
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial