Structured Co-Contamination Patterns of Foodborne Pathogens Across Raw Foods: Implications from a Decade-Long Public Health Surveillance Study in Gwangju, South Korea.
Globally, zoonotic bacterial pathogens like Salmonella spp. and pathogenic Escherichia coli remain leading causes of foodborne illness. While raw materials are critical exposure interfaces, long-term evidence regarding multi-pathogen co-contamination across food matrices is limited. We conducted a decade-long surveillance study (2016-2025) in South Korea, analyzing 4653 raw food samples-including livestock, agricultural, and marine products-for 12 zoonotic pathogens. Co-contamination was a structured, frequent feature, observed in 16.0% of livestock, 15.8% of agricultural, and 5.6% of seafood samples. Within livestock, chicken exhibited the highest co-contamination rate (27.4%), while pork showed the lowest (3.7%). Matrix-specific pathogen combinations predominated: pathogenic E. coli plus Clostridium perfringens in livestock; C. perfringens plus Bacillus cereus in agricultural products; and Vibrio parahaemolyticus plus V. vulnificus in marine products. Notably, enteropathogenic E. coli (EPEC) constituted 75.0% of pathogenic E. coli in poultry, whereas cattle showed diverse profiles including enterohemorrhagic (EHEC), enterotoxigenic (ETEC), and EPEC. Statistical analysis (Pearson's chi-square or Fisher's exact test) revealed no significant seasonal variation in contamination or co-contamination rates (all p > 0.56), suggesting that stable processing and handling factors exert more influence than climatic drivers. By conceptualizing multi-pathogen co-contamination as a reproducible feature of food systems rather than an incidental event, this study provides critical epidemiological insights into polymicrobial exposure. These findings support the transition toward multi-hazard, pattern-based surveillance and integrated risk-management strategies to enhance zoonotic foodborne disease prevention in public health systems.