Enteric pathogens and Carbapenem resistance genes are widespread in the fecal contaminated soils of cattle farms in the United States

Abstract

Cattle farming is considered a major contributor to antibiotic resistant (AR) genes and bacteria in nearby environments, predominantly due to the large amount of manure released by cattle to soils. This study sought to compare soil within and outside of cattle pens from seven farms in the US. Soil microbial community differences are described, as well as differences in AR gene and enteric pathogen concentrations in the soils. Sources of fecal loading are quantified via microbial source tracking (MST) methods. The family Peptostreptococcaceae was more abundant in pen soils, and Rhodanobacteraceae was more abundant in non-pen soils. There were no differences in microbial community diversity between soils within and outside of cattle pens. The MST result showed that ruminant-specific fecal contamination (Rum2Bac) was abundant both in pen and non-pen soils, likely indicating heavy cattle fecal loading. However, the soil within cattle pens had higher levels of Campylobacter, Salmonella, and AR genes for resistance to sulfonamides (sul1) and carbapenems (KPC) than the soil outside of pens (p<0.05). This is the first study identifying KPC in livestock-associated soils in the US. This study supports increased hazard associated with livestock soils for animal and human health, as well as environmental quality.

Keywords

• Soil microbial community
• Cattle farm
• Microbial source tracking
• Carbapenem resistance
• Soil reservoir