Antimicrobial Resistance Patterns in Bacterial Isolates from Poultry Farms in Osun State

The emergence of antimicrobial resistance in bacteria associated with poultry production is a growing One Health concern globally and within Nigeria. This study investigated antimicrobial resistance patterns in bacteria isolated from poultry farms in Osun State, South West Nigeria. Cloacal swabs and environmental samples were collected from 200 broiler and layer chickens across ten farms in three local government areas. Bacteria were isolated and identified using standard microbiological culture and biochemical tests. Antibiotic susceptibility testing was performed by the Kirby-Bauer disk diffusion method using a panel of 12 antibiotics. The most commonly isolated organisms were Escherichia coli and Salmonella species. High-level resistance was observed against tetracycline (78%), ampicillin (72%), and sulfonamides (65%). Multi-drug resistance, defined as resistance to three or more antibiotic classes, was identified in 46% of all isolates. Farms with documented history of prophylactic antibiotic use showed significantly higher resistance profiles. The study concludes that widespread antimicrobial resistance in poultry bacterial isolates in Osun State reflects the misuse of antibiotics in production systems and poses a significant public health risk through the food chain. Strict antibiotic stewardship policies, farmer education, and national antimicrobial resistance surveillance programs in livestock are urgently recommended. Keywords: antimicrobial resistance, poultry, Escherichia coli, Osun State, antibiotic stewardship