Characterization of CTX-M and SHV extended-spectrum β-lactamases and associated resistance genes in Escherichia coli strains of food samples in Tunisia

• Published in: Journal of antimicrobial chemotherapy 2007-11, Vol.60 (5), p.1137-1141
• Main Authors: Jouini, Ahlem, Vinué, Laura, Slama, Karim Ben, Sáenz, Yolanda, Klibi, Naouel, Hammami, Salah, Boudabous, Abdellatif, Torres, Carmen
• Format: Article
• Language: English
• Subjects: Animals; Antibiotics. Antiinfectious agents. Antiparasitic agents; beta-Lactamases - genetics; Biological and medical sciences; Cattle; Chickens - microbiology; CTX-M-1; CTX-M-14; CTX-M-8; Drug Resistance, Multiple, Bacterial - genetics; E. coli; Escherichia coli - drug effects; Escherichia coli - enzymology; Escherichia coli - genetics; Escherichia coli Proteins - genetics; Feces - microbiology; Fishes - microbiology; Food Microbiology; Horses - microbiology; Humans; Meat - microbiology; Medical sciences; Pharmacology. Drug treatments; Sheep - microbiology; SHV-5; Tunisia; Turkeys - microbiology
• ISSN: 0305-7453; 1460-2091
• DOI: 10.1093/jac/dkm316

Objectives To assess the occurrence of extended-spectrum β-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): blaCTX-M-1 (5), blaCTX-M-1 + blaTEM-1b (1), blaCTX-M-14 + blaTEM-1b (2), blaCTX-M-8 (1) and blaSHV-5 (1). All ESBL-positive isolates showed unrelated PFGE patterns. ISEcp1 and IS903 were detected surrounding blaCTX-M-14, and ISEcp1/IS26 and orf477 surrounding some of the blaCTX-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.