The link between antimicrobial resistance and seasonal change: Prevalence of ARGs, stress resilience, virulence and plasmids in raw milk Escherichia coli of Gujarat, India

This 2026 study investigates how seasonal changes influence antimicrobial resistance (AMR) in Escherichia coli isolated from raw milk in Gujarat, India, combining phenotypic testing with whole-genome sequencing. The researchers found that resistance levels, virulence factors, and genetic profiles vary significantly by season, with the highest antibiotic resistance observed during summer and monsoon periods. Importantly, key resistance genes (e.g., blaCTX-M-15, qnrS1) were present year-round and often located on plasmids, indicating a strong potential for horizontal gene transfer. Seasonal differences were also seen in stress tolerance and virulence traits, suggesting environmental conditions shape bacterial adaptation. Overall, the study highlights the need for season-aware AMR surveillance and One Health strategies linking food, environment, and human health.