Low Prevalence but High Clinical Relevance of AMR Salmonella in US Retail Meat

Key Findings: 

A total of 200 retail ground meat samples (ground turkey, pork, and beef) were collected between September 2022 and June 2024 and analyzed using the FDA National Antimicrobial Resistance Monitoring System (NARMS) retail meat surveillance protocol. Recovered isolates were further characterized using whole-genome sequencing (WGS).¹ The authors reported:

• Low Overall Prevalence with Product-Specific Distribution: Salmonella was detected in 8 of 200 samples (4%), indicating a relatively low but measurable prevalence in retail ground meats. Ground turkey accounted for the majority of positive samples, followed by ground pork and ground beef, consistent with national surveillance trends showing higher Salmonella recovery rates in poultry products.
• Clinically relevant S. enterica serovars identified:
  • Salmonella Infantis
  • Salmonella Reading
  • Salmonella Litchfield
  • Salmonella London
  • Salmonella Typhimurium monophasic variant I 4,[5],12:i:
• Clinical Significance: WGA determined that 7 of the 8 isolates showed genetic matches to clinical isolates archived in national genomic databases, indicating strong epidemiological relevance and support of the prevailing theory that retail meats can serve as reservoirs contributing to human salmonellosis cases.
• Evidence of Multidrug Resistance (MDR): Genomic analysis identified antimicrobial resistance (AMR) genes associated with resistance to up to six antimicrobial classes, indicating the presence of MDR isolates. 
• Detection of Fluoroquinolone Resistance Determinants: One Salmonella London isolate carried the qnrB19 plasmid-mediated fluoroquinolone resistance gene, a finding of particular concern given the importance of fluoroquinolones as frontline antimicrobials for treating severe Salmonella infections.

Bigger Picture:

Although limited by sample size and geographic scope, the findings of this study are consistent with broader national and global concerns related to antimicrobial resistance (AMR) in foodborne pathogens, particularly within retail meat systems. These results reinforce several ongoing trends observed in surveillance programs:

• Increasing multidrug resistance (MDR) among Salmonella serovars, including those frequently associated with human illness, continues to challenge both clinical treatment and food safety risk management.
• Persistence and dissemination of plasmid-mediated resistance genes, such as those conferring fluoroquinolone resistance, highlight the growing role of mobile genetic elements in accelerating resistance spread across bacterial populations and production environments.
• Poultry-associated Salmonella strains remain a major contributor to human salmonellosis, reflecting the biological and logistical complexities of controlling contamination within intensive poultry production and processing systems.
• Genomic surveillance is becoming central to modern food safety, as whole-genome sequencing enables high-resolution comparisons between food, environmental, and clinical isolates, strengthening source attribution and outbreak response capabilities. 

These findings support continued application of standardized surveillance frameworks, such as NARMS-based methods, to track emerging resistance trends and inform mitigation strategies across the food supply chain.

References:

1. Mallmann et al. 2026.  Prevalence and Antimicrobial Resistance of Salmonella Isolates from Retail Meats in Indiana, USA. Journal of Food Protection.