Case–Control Study of Factors Associated with Hemolytic Uremic Syndrome among Shiga Toxin–Producing <i>Escherichia coli</i> Patients, Ireland, 2017–2020

Shiga toxin-producing Escherichia coli (STEC) infection can cause potentially fatal hemolytic uremic syndrome (HUS). To determine epidemiologic and bacterial genomic factors associated with HUS, we conducted a retrospective case-control study with 108 HUS cases and 416 unmatched controls (non-HUS) selected among STEC notifications in Ireland during 2017-2020. We combined routinely collected epidemiologic data on STEC notifications with genomewide association study findings and used logistic regression to estimate adjusted odds ratios. Our findings reaffirmed known risk factors, such as young age (0-9 years) and presence of specific stx genes or gene combinations (stx2a; stx1a + stx2a; stx1a + stx2c), and additionally suggest that having outbreak-associated infection, residence within the East region of Ireland, and the combined presence of both ygiW and group_5720 or both pfkA and fieF genes are potentially associated with developing HUS. Our findings could improve early identification of high-risk STEC infections and help guide enhanced surveillance and public health management.