Twenty-Four Month Clinical and Laboratory Follow-Up of Children Infected During a Shiga toxin-Producing Escherichia coli Outbreak

Background Shiga toxin-producing Escherichia coli (STEC) infections can cause significant long-term renal sequelae. Intermediate-term outcomes for patients who do not develop hemolytic uremic syndrome (HUS) remain unclear. We evaluated clinical and laboratory outcomes in children with laboratory-confirmed STEC O157 infection in a large childcare outbreak. Methods This prospective longitudinal cohort study enrolled children aged 9 months to <6 years attending childcare centers in Calgary, Alberta, Canada during an STEC outbreak in September 2023. Among cases, clinical presentation was categorized as: asymptomatic, mild-moderate (diarrhea, no HUS), and severe (HUS). Cases were STEC-infected children confirmed by stool molecular testing; controls were exposed children whose stool tested negative by the same method. Outcome measures assessed at 6-, 12-, and 24-months post-exposure included: general assessments, inflammatory markers, hematologic parameters, renal function, gastrointestinal outcomes, and cardiometabolic markers. Results Of 932 eligible children, 145 (16%) participated: 72 cases (4 asymptomatic, 59 mild-moderate infection, 9 HUS) and 73 controls. Median age was 3.3 (IQR: 2.3, 4.2) years. After adjustment for multiple comparisons, no laboratory parameters or clinical outcomes differed between groups at any timepoint. Functional gastrointestinal disorders occurred at similar rates across groups, except functional dyspepsia was more common among STEC-infected children at 6-month follow-up. At 24 months, median eGFRs were similar across groups. One of 9 (11%) children with HUS had proteinuria and hematuria at 24 months. Conclusions Among children with STEC infection without HUS, no evidence of persistent clinical symptoms or laboratory abnormalities emerged during 24-month follow-up compared with controls, providing reassurance regarding intermediate-term outcomes.