NARMS at FSIS – The Critical Role Food-Producing Animal Sampling Plays in Creating an Integrated National Antimicrobial Resistance Picture

NARMS at FSIS - The Critical Role Food-Producing Animal Sampling Plays in Creating an Integrated National Antimicrobial Resistance Picture

Uday Dessai, Gamola Fortenberry, Catherine Rockwell, Jovita Haro, and Bonnie Kissler

USDA Food Safety and Inspection Service

The National Antimicrobial Resistance Monitoring System (NARMS) is a collaborative antimicrobial resistance (AMR) monitoring program, and a core component of the U.S. National Action Plan to Combat Antimicrobial Resistant Bacteria (CARB). Within the U.S. national biosecurity framework, AMR is identified as a naturally occurring biological threat. NARMS serves an early-warning system to detect high-consequence resistant bacteria in the food supply and provides the strategic framework for the U.S. government's work to preserve the effectiveness of critical life-saving antimicrobials for human and animal use.

NARMS monitors AMR across the food chain in ill people (Centers for Disease Control and Prevention (CDC)), processed meat and poultry (United States Department of Agriculture (USDA)), retail meats (Food and Drug Administration (FDA)), and intestinal/cecal contents from animals at slaughter (USDA). This continuous, nationally representative surveillance provides the scientific data needed to assess antibiotic effectiveness, guide interventions, and inform public health decisions. Ensuring that the NARMS data are accurate, reliable, representative, and current requires systematic planning and statistical rigor, given the complexity of U.S. food animal production, distribution, and movements.

FSIS has a unique ability to collect nationally representative cecal content samples because food animals intended for slaughter must enter FSIS-regulated establishments. To achieve representative sampling, FSIS stratifies slaughter establishments into three categories based on the numbers of animals slaughtered: the top 25% are sampled up to 4 times per month, the next 25% up to twice per month and the remaining 50% once per month. This sampling design captures meaningful variation across establishment sizes.

To produce statistically robust national estimates of AMR in food producing animals, FSIS aims to recover at least 1,200 isolates each of Salmonella, Campylobacter, E. coli, and Enterococcus from poultry, cattle and swine. Based on years of isolate recovery experience, reaching those targets takes roughly 5,100 cecal samples a year. This sample size provides 95% confidence in national resistance prevalence estimates. For emerging or new resistance (estimated at about 5% prevalence rate), this approach provides a narrow ±1.2% margin of error. This precision is essential for ensuring that the data reported are a reliable reflection of the national population. When combined with FSIS product and FDA retail meat data, FSIS cecal AMR data provides a comprehensive national AMR picture across food-producing animals. Integration with human AMR data further supports early detection of actionable trends from both public health and national biosecurity perspectives.

The FSIS NARMS program plays a critical role in developing an overall integrated national AMR snapshot and is central to establishing a national AMR baseline in food-producing animals. By generating representative, reliable, and actionable data, FSIS supports effective antimicrobial stewardship efforts and helps ensure that essential antimicrobials remain effective for our current and future One Health needs.