Antibiotic susceptibility profile of Escherichia coli isolated from poultry settings

Poultry production contributes significantly to environmental antibiotic resistance, particularly through manure-amended soils. This study evaluated the antibiotic susceptibility of Escherichia coli isolated from soils amended with conventional poultry manure (Site A), local poultry droppings (Site B), and unamended control soils (Site C). Isolates were confirmed via Gram staining and biochemical tests, and then subjected to disc diffusion testing using ten antibiotics, as per the CLSI 2024 guidelines. E. coli from Site A exhibited significantly reduced susceptibility to trimethoprim-sulfamethoxazole (11.5 ± 1.50 mm), streptomycin (14.1 ± 3.08 mm), and sparfloxacin (16.1 ± 2.85 mm) compared to Site C (p < 0.05). Site C consistently showed higher inhibition zones across most antibiotics, indicating lower resistance to these antibiotics. While Site B isolates showed intermediate resistance, differences from Site C were not statistically significant. Two-way ANOVA confirmed significant effects of both antibiotic type (p = 0.0003) and sample site (p < 0.0001) on resistance patterns. These findings underscore the role of poultry farming practices, particularly conventional systems, in promoting soil-based antimicrobial resistance, warranting stricter regulation and improved manure management.