An investigation of antimicrobial resistance (AMR) among important foodborne pathogens isolated from poultry between 2015 and 2023 has revealed certain trends. The study was authored by researchers from Villanova University and Immaculata University.

For the analysis, AMR data for chicken and turkey was extracted from the U.S. National Institutes of Health’s (NIH’s) National Center for Biotechnology Information (NCBI) Pathogen Isolates Browser for the period 2015–2023. The data included pathogens that demonstrated resistance to at least one antimicrobial. The majority of data related to Salmonella enterica, Escherichia coli, Shigella, and Campylobacter jejuni.

The years 2015–2023 were chosen as the reporting period due to significant policy actions taking place during this time, including the launch of the U.S. National Action Plan for Combating Antibiotic-Resistant Bacteria (CARB) in 2015, which greatly enhanced AMR monitoring efforts in sectors like poultry production.

The most prevalent resistant pathogen in both chicken and turkey was S. enterica, present in 64.04 percent and 72.73 percent of cases, respectively. Resistant C. jejuni was much more common in chicken (28.35 percent) than in turkey (1.29 percent), while E. coli and Shigella were more prevalent in turkey (25.98 percent, combined) than in chicken (7.61 percent, combined).

Tetracycline is the antibiotic to which most pathogens in both chicken and turkey samples showed resistance, followed by streptomycin. However, for chickens, sulfisoxazole was the third most resisted antimicrobial, followed by ampicillin and nalidixic acid. For turkey, ampicillin ranked third, followed by sulfisoxazole and gentamicin. Additionally, regional analysis showed that AMR cases in chicken are often concentrated in specific regions, such as Minnesota, while in turkey, the cases are more evenly distributed across the Midwest and other areas of the U.S.

Analysis of the data indicated regional variations in the concentrations of resistant pathogens that highlight the influence of local agricultural practices on pathogen distribution and AMR patterns. Specifically, a significant S. enterica outbreak occurred in the Northeast U.S. in 2019, with high concentrations in New York, Connecticut, Pennsylvania, and Maryland. The outbreak was particularly prominent in chicken samples, but also affected turkey. Outbreaks in other regions, including California, Georgia, New York, and Minnesota, reflect areas where larger human populations may be at greater risk of pathogen exposure through food sources. Additionally, the regional prevalence of C. jejuni in chicken, especially in California and Georgia, aligns with other scientific literature linking high-density poultry farming to increased C. jejuni presence.

Over time, S. enterica was the most prevalent resistant pathogen in both chicken and turkey, peaking in 2015 and 2019. C. jejuni was more common in chicken, showing elevated levels from 2017–2019, while E. coli and Shigella were more prevalent in turkey during 2018–2019. These trends were mirrored in key AMR genes that also peaked in 2019 and decreased significantly by 2022. Similarly, resistance to certain antibiotics followed the same pattern, with a spike in 2019 and a decline by 2022. This alignment across pathogens, genes, and antimicrobials suggests a widespread impact of AMR outbreaks and possible changes in the pathogen spread or detection practices during this period, according to the study's authors.

The researchers note that the decline in AMR after 2019 may have been driven by a combination of improved biosecurity measures and regulatory changes, although the potential impact of the COVID-19 pandemic on AMR surveillance and detection cannot be overlooked.