Abstract
BACKGROUND AND AIM: Colibacillosis is caused by avian pathogenic Escherichia coli (APEC), which results in significant losses for the poultry sector. It has zoonotic potential and acts as a source of antibiotic resistance and virulence genes for other E. coli. This study aimed to assess phylogenetic groups, virulence factors, and resistance phenotypes of APEC strains isolated from broiler farms in Northern Palestine. MATERIALS AND METHODS: A total of 65 APEC isolates were recovered from diseased chickens with typical colibacillosis symptoms from broiler farms located in the northern region of Palestine from May to July 2024. Strains were identified using classical and molecular techniques. Antibiotic resistance was detected using the disk diffusion method. Phylotyping and virulence genotyping of the APEC isolates were performed using a polymerase chain reaction (PCR). RESULTS: This study showed a high detection rate of APEC strains (100%) in chickens. The most APEC strains, 56/65 (86.2%), belonged to group D. Other strains were assigned to groups B2 (5/65, 7.7%), B1 (3/65, 4.6%), and A (1/65, 1.5%). Antibiotic resistance ranged from 27.7% for Polymyxin E (colistin) to 100% for Amoxicillin. Polymyxin E (colistin) and fosfomycin are the most effective drugs. The most common virulence gene was iroN, which was detected in 61 isolates (93.8%). The APEC strains in Palestine exhibit a wide variety of resistance patterns and genetic variations. CONCLUSION: Controlling APEC infections is essential for public health, especially when APEC isolates can pass on resistance and virulence genes to dangerous bacteria such as E. coli that are particular to humans. It is essential to understand APEC pathogenesis, antimicrobial therapy, and the development of measures to control colibacillosis.