Industrial food animal production: A driver of antimicrobial resistance and environmental pollution by resistance genes

The industrialization of food animal production, specifically the widespread use of antimicrobials, is now the major user of antimicrobial drugs in the US (over 70% of annual drug production is utilized as feed additives for poultry, swine, fish, and other animals). This practice is associated with increased pressure on microbial populations leading to selection for drug resistance and resulting in compromised food safety, occupational exposures, and environmental contamination. Most recently, compelling evidence has demonstrated associations between poultry and livestock production methods and the presence of methicillin resistant Staphylococcus aureus in animals, animal wastes, and consumer food production. An ecological perspective reveals that industrial food production has profoundly altered the ecosystem of agriculture and ecosystems that are contacted by inputs and outputs from this mode of production. Despite many studies around the world on this problem, and actions to reduce antjmicrobial use in the EU, industry has continued to resist change. We have examined these changes through an an ecosystem perspective in which antibiotic resistance genes can be considered environmental pollutants and the practices in industrial food animal production as drivers to alter natural microbiomes and to expand reservoirs of resistance. Studies on MRSA exemplify the current situation in which the agricultural-driven resistance reservoir now contaminates hospitals and serves as the major source of resistance in other pathogens.