PREVALENCE OF SHIGA TOXIN-PRODUCING <i>ESCHERICHIA COLI</i> STRAINS ON PIG FARMS IN TAIWAN

To investigate the prevalence of edema disease (ED) in Taiwan, fecal samples were collected from nursery and finishing pigs across six counties with the highest pig populations. The fecal samples were cultured in enrichment medium, and the virulence genes and serotypes of Shiga toxin-producing Escherichia coli (STEC) were analyzed using a PCR assay. Among the positive farms, the prevalence rates of stx1, stx2, and eae genes in nursery and finishing pigs were 0%, 88.9% (40/45), and 97.8% (44/45), respectively. A significantly higher prevalence of stx2 was observed in nursery pigs fed self-formulated feed compared to those fed commercial feed (p ¡ 0.01). High crude protein (CP) levels in feed may contribute to indigestion and malabsorption, increasing the risk of compromised intestinal health. Excess dietary protein can alter the gut microbial community by reducing beneficial bacteria and promoting pathogenic bacterial proliferation. Notably, serogroup O8 (86.6%) was the most prevalent among STEC strains, followed by O91 (64.4%) and O174 (60.0%). Both O8 and O91 have been previously isolated from human patients. Our findings indicate that STEC is widespread in Taiwanese pig farms and that inappropriate CP formulations in feed may increase the prevalence of ED in nursery pigs. Additionally, some STEC serogroups associated with human infections pose a critical public health concern.