Escherichia coli is known as one of the most important foodborne pathogens in humans. Contaminated chicken meat is an important source of foodborne infection with this bacterium. A total of 144 fresh chicken meat samples (72 from chicken breasts and 72 from chicken thighs) were collected from different six farms so that 24 samples were collected from each farm. One of the farms was considered as a control, as its poultry did not receive any antibiotics as food promoters, while chickens in the remaining five farms received antibiotics (Doxycycline 50% and Tylosin 20%). In addition, 72 chicken liver samples were collected from the six farms (12 samples per farm) to estimate levels of antibiotic residues. Results revealed that the prevalence of Escherichia coli in chicken thigh samples collected from Farms 4 and 5 were 25% (3/12) and 16.6% (2/12), respectively. In contrast, chicken breast samples from all farms were free from Escherichia coli. Serological identification of the five Escherichia coli isolates revealed that they were O91: H21 (EHEC) and O2: H6 (EPEC) with a prevalence of 16.7% (n=2) and 8.33% (n=), respectively in chicken thigh samples from Farm 4, while isolates from Farm 5 were serotyped as O78 (ETEC) and O44: H18 (EPEC) in chicken thigh samples with a prevalence rate of 8.33% for each serotype. Antibiotic resistance pattern using Vitek 2 revealed that all Escherichia coli isolates were ESBL negative and showed resistance to Trimethoprim/ Sulfamethoxazole, Piperacillin, Ticarcillin, and Ciprofloxacin but were sensitive to other antibiotics used. HPLC was used to estimate the level of antibiotic residues in chicken liver. No residues were detected in 2 farms in addition to the control farm. Liver samples obtained from the remaining 3 tested farms were found to contain Doxycycline (851 mg/kg), Oxytetracycline (115 mg/kg) and Oxytetracycline (117 mg/kg), respectively. This study underlines that more strict regulations are required for the use of antimicrobial drugs in poultry industry as well as the monitoring for drug residues prior to marketing.
Key words: Escherichia coli, antimicrobial resistance, Vitek 2, HPLC, drug residues
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