Intensive farming may yield a bumper crop of drug-resistant pathogens

A new study has revealed that intensive farming methods, particularly those common in the U.S. Corn Belt, may contribute to the spread of antibiotic-resistant pathogens. Published in Proceedings of the National Academy of Sciences, the research compared four farming techniques: high-intensity corn cropping with heavy tilling, synthetic fertilizers, and non-antibiotic biocides; two medium-intensity cropping schemes with reduced biocides and tilling, and use of cow manure; and low-intensity grazing rotated with no-till cover crops.

The study found that high-intensity farming produced soil microbiomes more likely to transmit antibiotic-resistant pathogens to humans compared to lower-intensity methods. Intensive farming, which includes heavy tilling, synthetic fertilizers, and biocides, tends to have lower bacterial diversity and thus provides a better environment for bacteria harboring antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) to survive and spread.

Additionally, environmental stressors such as synthetic fertilizers, copper-containing biocides, and tilling in high-intensity fields favor bacteria with ARGs and MGEs.

The researchers estimated that the risk of transmission of pathogens acquiring ARGs and infecting humans is significantly higher in high-intensity fields than in medium-intensity fields. While intensive farming is already associated with high greenhouse gas emissions and water pollution, this study also highlights an additional, unrecognized cost: the facilitation of drug-resistant pathogen spread.

The authors suggest that soil and crop management practices could be strategically leveraged to limit the spread of these dangerous pathogens.