Geospatial Health 2025; 20:1416
15 December 2025
A recent systematic review published in Geospatial Health highlights a critical serovar shift in the U.S. poultry industry. While control measures have successfully reduced traditional serotypes, Salmonella infantis has rapidly emerged as a dominant and multidrug-resistant (MDR) pathogen in broiler systems.
Between 2015 and 2020, S. infantis prevalence in raw chicken parts surged from less than 4% to nearly 25%. Models predict that without targeted intervention, S. infantis is on a trajectory to become the dominant serotype in chicken parts. The review identifies S. infantis as the primary driver of rising antibiotic resistance in poultry products. While resistance trends for S. enteritidis, S. typhimurium, and S. kentucky have remained flat or declined, the fraction of isolates resistant to critically important antibiotics has doubled, a trend attributable almost entirely to S. infantis. The rise of S. infantis appears to be an unintended consequence of successful interventions against other serovars. The sharp decline in S. enteritidis and S. kentucky suggests that current vaccines are effective against those specific targets but have left an ecological niche open for S. infantis, for which specific vaccines are less widely utilized or effective. S. infantis is specifically linked to heat-stressed broilers, particularly in the Southeast United States. This suggests that climate control and stress management in grow-out houses may be critical components of S. infantis mitigation, alongside biosecurity. The findings suggest that current vaccination and control protocols must evolve. Reliance on broad interventions or vaccines targeting only S. enteritidis is insufficient to curb the spread of MDR S. infantis. Future strategies requires serotype-specific vaccines and updated biosecurity measures that account for environmental persistence.
