title: Characterization of CTX-M and SHV extended-spectrum beta-lactamases and associated resistance genes in Escherichia coli strains of food samples in Tunisia.
abstract: OBJECTIVE
  To assess the occurrence of extended-spectrum beta-lactamases (ESBLs) in Escherichia coli isolates of faecal samples of animals (n = 40) and food samples (n = 38) obtained in Tunisia in 2006, and to characterize the type of ESBLs, their genetic environments and the associated resistance genes.
  
  
  METHODS
  Samples were inoculated in supplemented media (2 mg/L cefotaxime) for isolation of broad-spectrum cephalosporin-resistant E. coli isolates (one isolate/sample). ESBLs and their genetic environments as well as integrons and their gene cassette composition were characterized by PCR and sequencing.
  
  
  RESULTS
  ESBL-producing E. coli isolates were detected in 10 of the 38 food samples analysed (26%) and in none of the tested animal faecal samples. Genes found were as follows (number of isolates): bla(CTX-M-1) (5), bla(CTX-M-1) + bla(TEM-1b) (1), bla(CTX-M-14) + bla(TEM-1b) (2), bla(CTX-M-8) (1) and bla(SHV-5) (1). All ESBL-positive isolates showed unrelated PFGE patterns. ISEcp1 and IS903 were detected surrounding bla(CTX-M-14), and ISEcp1/IS26 and orf477 surrounding some of the bla(CTX-M-1) genes. Four of the ESBL-positive strains harboured class 1 integrons including different gene cassette combinations.
  
  
  CONCLUSIONS
  ESBLs, mainly of the CTX-M class, are detected in E. coli of food origin in Tunisia, being the first time that this mechanism has been detected in food E. coli strains in Africa.
authors.affiliation: Laboratoire MBA, Département de Biologie, Faculté de Sciences de Tunis, Campus Universitaire, 2092 Tunis, Tunisia.
authors.forename: Ahlem
authors.initials: A
authors.lastname: Jouini
authors.forename: Laura
authors.initials: L
authors.lastname: Vinué
authors.forename: Karim Ben
authors.initials: KB
authors.lastname: Slama
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Sáenz
authors.forename: Naouel
authors.initials: N
authors.lastname: Klibi
authors.forename: Salah
authors.initials: S
authors.lastname: Hammami
authors.forename: Abdellatif
authors.initials: A
authors.lastname: Boudabous
authors.forename: Carmen
authors.initials: C
authors.lastname: Torres
mesh_terms: D000818:Animals; D002417:Cattle; D002645:Chickens / Q000382:microbiology; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000235:genetics*; D005243:Feces / Q000382:microbiology; D005399:Fishes / Q000382:microbiology; D005516:Food Microbiology; D006736:Horses / Q000382:microbiology; D006801:Humans; D008460:Meat / Q000382:microbiology; D012756:Sheep / Q000382:microbiology; D014416:Tunisia; D014422:Turkeys / Q000382:microbiology; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D029968:Escherichia coli Proteins; D001618:beta-Lactamases