Occurrence of non-O157 Shiga toxin-producing Escherichia coli in two commercial swine farms in the Eastern Cape Province, South Africa

Shiga toxin-producing Escherichia coli (STEC) is one of the most significant causes of food-borne infections capable of causing serious health complications in humans. Even though ruminants are known to be the major reservoirs of STEC, other non-ruminant food producing animals may also harbour pathogenic E. coli strains. In this study, we investigated the prevalence of E. coli serogroups O26, O111, O121, O145, and O157 and their associated virulence genes (stx1, stx2, eae, and ehxA) in swine faecal samples obtained from the two major commercial farms located in the Nkonkobe Municipality, Eastern Cape, South Africa. The proportions of serogroups detected were O26; 35 (7%), O145; 14 (2.8%), and O157:H7; 43 (8.6%) of the total animals sampled. Out of the 500 animals sampled, 22 isolates of E. coli (1.4%) tested positive for the stx2 gene, and 7 of these isolates belonged to E. coli O26 serogroup, while the remaining 15 most likely belonged to serogroups untargeted in this study. Other virulence genes (stx1, eae, and ehxA) that we screened for were not detected. These findings reveal that pigs within the Eastern Cape Province of South Africa can harbour Shiga toxin-producing E. coli.