A review of Shiga-toxin producing Escherichia coli (STEC) contamination in the raw pork production chain.

Epidemiological evidence of Shiga toxin-producing Escherichia coli (STEC) infections associated with the consumption of contaminated pork highlight the need for increased awareness of STEC as an emerging pathogen in the pork supply chain. The objective of this review is to contribute to our understanding of raw pork products as potential carriers of STEC into the food supply. We summarize and critically analyze primary literature reporting the prevalence of STEC in the raw pork production chain. The reported prevalence rate of stx-positive E. coli isolates in live swine, slaughtered swine, and retail pork samples around the world ranged from 4.4 % (22/500) to 68.3 % (82/120), 22 % (309/1395) to 86.3 % (69/80), and 0.10 % (1/1167) to 80 % (32/40), respectively, depending upon the sample categories, detection methods, and the hygiene condition of the slaughterhouses and retail markets. In retail pork, serogroup O26 was prevalent in the U.S., Europe, and Africa. Serogroup O121 was only reported in the U.S. Furthermore, serogroup O91 was reported in the U.S., Asia, and South American retail pork samples. The most common virulence gene combination in retail pork around the globe were as follows: the U.S.: serogroup O157 + stx, non-O157 + stx, unknown serogroups+stx + eae; Europe: unknown serogroups+(stx + eae, stx + eae, or stx + stx + eae); Asia: O157 + stx + stx + ehxA, Unknown+stx + eaeA + ehxA, or only eae; Africa: O157 + stx + eae + ehxA. STEC strains derived from retail pork in the U.S. fall under low to moderate risk categories capable of causing human disease, thus indicating the need for adequate cooking and prevention of cross contamination to minimize infection risk in humans.