Abstract
The emergence of AmpC β-lactamases-producing Escherichia coli (E. coli) strains in poultry, especially in broiler chickens suffering from Avian Metapneumovirus (AMPV) infections, is a growing concern due to the potential for antibiotic resistance. Current study purposes to assess the prevalence of AmpC β-lactamase-producing E. coli isolates in broiler chickens in Duhok, a region in northern Iraq, and to evaluate the effectiveness of phenotypic screening methods for detecting these resistant strains. A total of 100 samples from clinically affected broiler chickens were collected and cultured for the isolation of E. coli. The phenotypic screening was achieved using three methods, acidimetric, ESBL and ESBL-ampC, were collected from September 2024 to March 2025. The results revealed that a significant proportion of E. coli isolates (68% acidimetric), (22% ESBL) and (38% ESBL-ampC) respectively were positive. The phenotypic tests showed varying sensitivity and specificity, with the combined disc test demonstrating the highest accuracy in identifying AmpC-producing strains. This study highlights the prevalence of AmpC β-lactamases in E. coli isolates from poultry infected with AMPV and emphasizes the need for regular surveillance and the application of effective antimicrobial programs to manage the spread of resistance in veterinary settings.