Occurrence of Selected Bacterial Antibiotic Resistance Genes in Soils of Animal Farms in Uganda

Abstract

The antibiotic resistance genes (ARG) of bacteria can be found in diverse environments such as the gut of mammals, soil, air, and water. In this research, we examined soils (for ARG) from 27 animal farms in Uganda (Mbarara, Wakiso and Mpigi districts) rearing poultry, pigs, dairy, or beef animals. Among these 27 places, there were antibiotic-free farms and those, which routinely used antibiotics to control diseases. DNA was extracted from soil samples using a commercial kit. A polymerase chain reaction (PCR) was performed to detect baScterial genes of resistance to sulphonamide (3 genes), beta lactam (1 gene), and Tetracycline (8 genes) antibiotics. The highest number of soils contaminated with these genes were from Mpigi district, whereas in Mbarara we found contamination of farm soils to a lesser extent. In all districts, the ARG were detected in farm soils regardless of the evidence of antibiotic usage; however, ARG were predominant in severe antibiotic consuming farms than the less consuming ones. Sulphonamide resistance genes were predominant in most district samples. In particular, the sul2 (Sulphonamide) and tetW (Tetracycline) genes were the most prevalent in all samples, suggesting that fecal disposal or use of animal manure could drive the accumulation of ARG in these soils, making it a deadly reservoir, especially in areas with vast consumption of antibiotics.