Prevalence and characteristics of Shiga toxin-producing Escherichia coli in finishing pigs: Implications on public health

Abstract Shiga toxin-producing Escherichia coli (STEC) are important food-borne pathogens, which can cause serious illnesses, including hemorrhagic colitis and hemolytic uremic syndrome. To study the epidemiology of STEC in finishing pigs and examine the potential risks they pose for human STEC infections, we conducted a longitudinal cohort study in three finishing sites. Six cohorts of pigs (2 cohorts/site, 20 pigs/cohort) were randomly selected, and fecal samples ( n  = 898) were collected every two weeks through their finishing period. Eighty-two pigs (68.3%) shed STEC at least once, and the proportion of STEC-positive pigs varied across sites (50–97.5%) and cohorts (15–100%). Clinically important serotypes, O157:H7 ( stx 2c , eae ) and O26:H11 ( stx 1a , eae ), were recovered from two pigs at sites C and A, respectively. The most common serotype isolated was O59:H21 ( stx 2e ), which was particularly prevalent in site B as it was recovered from all STEC positive pigs ( n  = 39). Each cohort showed different patterns of STEC shedding, which were associated with the prevalent serotype. The median shedding duration of STEC in pigs was 28 days, consistent with our prior study. However, among pigs shedding O59:H21 at least once, pigs in cohort B2 had a significantly longer shedding duration of 42 days ( P