Pig production system drivers of antibiotic resistance in Uganda

Abstract As population-driven demand for protein grows, shifts to livestock intensification in low- and middle-income countries (LMICs) increase risks of antibiotic overuse and antibiotic resistance (ABR). Focusing on Uganda as a fast-growing pig producer in Africa, we examined the potential impact of this transformation. Pigs reared in semi-intensive systems carry six times more antibiotic-resistant bacteria and significantly more ABR encoding genes in their guts than free-range pigs. ABR levels in farmers and pigs in semi-intensive systems were similarly high(22.5%), whereas in free-range pigs they were half those of the farmers who managed them (9% and 21%, respectively). ABR increased at an average rate of 0.7% during the study. Pig-Farmer transmission was ~3 times more likely on semi-intensive farms and associated with differences in abundance of ABR encoding genes in the gut of farmers and their pigs. Shifts to intensified livestock farming require managing enhanced risks of ABR emergence and cross-species transmission.