The evaluation of ESBL genes and antibiotic resistance rate in Escherichia coli strains isolated from meat and intestinal contents of turkey in Isfahan, Iran

Extended spectrum beta-lactamase (ESBL) has been described in Escherichia coli strains that have been isolated from humans and animals; it has induced a main concern with antibiotic resistance in serious bacterial infections.

This study aimed to investigate the frequency of ESBL-producing E. coli (EPE) strains in meat and intestinal contents of turkey, and to compare the antibiotic resistance profile between EPE and non-EPE strains.

Totally, 70 and 110 E. coli strains were isolated from turkey meat and turkey intestinal content samples, respectively. To determine EPE strains, double disc synergy test was applied by that 20 and 22 EPE strains were finally identified in meats and intestinal contents of the turkeys, respectively. Antibiotic susceptibility was exerted using disc diffusion method. Escherichia coli isolates were then characterized for virulence genes (stx-1 and stx-2) and ESBL genes (TEM, SHV, and CTX-M).

None of the E. coli strains harbored stx genes. The EPE strains in comparison with non-EPE strains were significantly more resistant to ciprofloxacin (47.6 vs 26.5%), tetracycline (80.9 vs 67.3%), ampicillin (47.6 vs 22.4%), penicillin (23.8 vs 10.2%), ceftazidime (57.1 vs 16.3%), ceftriaxone (38.1 vs 18.4%), and cefotaxime (47.6 vs 8.2%). The majority of EPE strains carried CTX-M gene. SHV showed the lowest frequency and it was not detected in EPE strains isolated from the intestinal contents. In this study, 75% of TEM-producing E. coli strains and 33% of SHV-producing E. coli strains were resistant to ampicillin. In addition, 41.7% of TEM-producing E. coli strains were resistant to penicillin, and 76.9% of CTX-producing E. coli were resistant to cefotaxime. Furthermore, 4.7% of EPE strains isolated from turkey meat were imipenem resistant.

The resistance to cefotaxime and imipenem in EPE strains induces a concern in growing antibiotic resistance against broad spectrum antibiotics in E. coli strains.