High prevalence of extended spectrum and plasmidic AmpC beta lactamase producing Escherichia coli from poultry in Tunisia.
This study was conducted to detect extended spectrum beta lactamases (ESBLs) and plasmidic AmpC beta lactamase (pAmpC BL) producing Escherichia coli isolates in industrial poultry samples were collected from healthy chickens of the three farms. Samples were inoculated onto desoxycholate lactose agar plates supplemented with cefotaxime (2mg/L) E. coli was identified by biochemical and molecular methods and antibiotic susceptibility testing by the disk diffusion method. Genes encoding ESBLs and pAmpC BL were detected by PCR and sequencing. Phylogenetic groups were determined by triplex PCR. The molecular typing of strains was done by pulsed field gel electrophoresis (PFGE) and Multilocus Sequence Typing (MLST) in those isolates showing different PFGE patterns. Cefotaxime resistant E. coli isolates were recovered in 48 of 137 fecal samples (35% and one isolate/sample was further studied. The following beta lactamase genes were detected: blaCTX M 1 (29 isolates, isolated in all three farms) blaCTX M 15 (5 isolates, confined in farm II) blaCTX M 14 and blaCMY 2 (one isolate and 13 isolates, respectively, in farm III) The 48 cefotaxime resistant isolates were distributed into phylogroups: B1 (n=21) A (n=15) and D (n=12) PFGE analysis revealed 19 unrelated patterns: 15 different profiles among ESBL positive strains and 4 among the CMY 2 positive isolates. The following sequence types associated phylogroups were detected: a) CTX M 1 positive strains: lineages ST542 B1, ST212 B1, ST58 B1, ST155 B1 and ST349 D; b) CTX M 15 positive strain: lineage ST405 D; c) CTX M 14 positive strain: lineage ST1056 B1; d) CMY 2 positive strains: lineages ST117 D, ST2197 A, and ST155 B1. Healthy chickens constitute an important reservoir of ESBL and pAmpC BL producing E. coli isolates that potentially could be transmitted to humans via the food chain or by direct contact.
International journal of food microbiology