An analysis of a decade of antimicrobial resistance (AMR) surveillance data in foodborne pathogens has identified patterns shaping multidrug resistance (MDR) in food animal production systems. The study was published in MDPI and conducted by Villanova University researchers.

The researchers examined 9,393 isolates of Salmonella enterica, Campylobacter jejuni, and Escherichia coli collected from poultry, cattle, and swine between 2015 and 2025, using data from the U.S. National Institutes of Health’s (NIH’s) National Center for Biotechnology Information (NCBI) Pathogen Isolates Browser.

The dataset was analyzed to characterize AMR patterns in isolates showing resistance to one to six antimicrobials, finding that tetracycline, streptomycin, sulfisoxazole, ampicillin, nalidixic acid, and ciprofloxacin consistently formed the dominant axes of co-resistance across pathogens. This reflects long-standing selective pressures in food animal production systems.

Tetracycline emerged as the most influential driver, appearing in nearly all MDR isolates.

C. jejuni largely showed single-drug resistance. S. enterica accounted for nearly all cases of complex multidrug resistance, especially in isolates resistant to five or six antimicrobials, through the accumulation of several resistance determinants.

Gene analysis revealed a progressive, modular accumulation of resistance determinants, especially efflux pump genes, tetracycline resistance genes, aminoglycoside-modifying enzymes, sulfonamide genes, fluoroquinolone resistance determinants, and β-lactamases.

These findings suggest that MDR evolves through coordinated gene–drug–pathogen interactions rather than random or isolated events, arising through the progressive assembly of stable resistance gene modules, underscoring the need for integrated surveillance and targeted antimicrobial stewardship strategies focused on the dominant antimicrobials and high-risk foodborne pathogens.

Researchers recommend future work that expands surveillance to include more pathogens, antimicrobials, and international data, as well as improving annotations to distinguish between production, processing, retail, and outbreak sources.

Overall, the study reinforces the urgent need for integrated phenotypic and genotypic surveillance strategies targeting high-risk pathogens and dominant antimicrobials. By understanding the stepwise progression of AMR, public health and agri-food stakeholders can better anticipate resistance trends and implement targeted antibiotic stewardship measures in food animal production systems.