A recent study has identified a high abundance and diversity of antibiotic resistance genes (ARGs) in commonly consumed retail foods, underscoring what researchers described as “a significant public health concern” related to the transmission of foodborne pathogens.

Published in LWT, the study was conducted by researchers at the University of Tennessee, Knoxville, the U.S Food and Drug Administration (FDA), and the University of Illinois Urbana–Champaign.

The researchers analyzed retail cabbage, lettuce, chicken legs, and deli meats collected from low- and high-socioeconomic status neighborhoods in Memphis, Tennessee, using shallow whole-metagenome shotgun sequencing (sWMS) and quantitative polymerase chain reaction PCR (qPCR). Across all samples, researchers detected a diverse array of ARGs representing various antibiotic classes, with multidrug resistance identified as the dominant ARG class.

All food samples contained potential pathogen-associated ARGs. Chicken legs from stores in high-income areas exhibited the highest ARG abundance, followed by deli meats from high-income stores. However, ARG richness and evenness did not differ significantly among sample groups.

Deli Meats and Produce Identified as Higher-Risk Categories

Emerging ARG analysis identified deli meats as high-risk regardless of store type. Researchers detected several genes associated with methicillin-resistant Staphylococcus aureus (MRSA). The abundance of Staphylococcus aureus was also reported to be high in these samples.

The study also found that cabbage and chicken from high-income stores carried the highest abundance of ARGs classified as Risk Group I, defined as mobile ARGs directly associated with human pathogens. According to the researchers, the occurrence of ARGs in cabbage and chicken collected from high-income stores may increase potential health risks.

Although poultry is a recognized reservoir of antibiotic-resistant bacteria (ARB), the authors noted that the risk of ARB can be lowered if animal products are adequately prepared and cooked. In contrast, ready-to-eat (RTE) deli meats and produce are mostly consumed without any further processing or cooking, increasing ARB exposure risks.

Factors Influencing ARG Distribution

The researchers reported that differences in ARG abundance between foods from low-income and high-income stores were not statistically significant, although some variation was observed. They attributed these differences to factors including agricultural practices, antibiotic use, storage conditions, sanitation practices, and environmental conditions such as temperature and humidity.

Additionally, the researchers explained that soil acts as a major reservoir of ARGs, and that antibiotic residues in agricultural environments may promote the transfer of resistance genes from non-pathogenic to pathogenic bacteria.

Strong Correlation Between ARGs and Pathogens

Network analysis revealed “a robust positive correlation” between ARGs and bacterial genera, including Pseudomonas, Enterobacter, Enterococcus, Serratia, Pantoea, and Weissella. The presence of these bacteria, which are known reservoirs of ARGs, may contribute to the persistence and spread of antimicrobial resistance (AMR) in the food supply.

The researchers also reported a statistically significant correlation between ARGs and microbial community composition, suggesting that environmental and handling conditions may influence ARG prevalence.

Implications for Industry

The study concluded that the presence of ARGs and associated pathogens in food poses a significant public health concern, and that retail foods may act as vehicles for the transmission of ARGs through ARB.

The authors emphasized that integrating metagenomic sequencing with qPCR improves detection accuracy and provides a more comprehensive assessment of ARG profiles. They suggested that this combined approach could support AMR surveillance and inform targeted interventions to reduce risks across the food supply chain.