Hemolytic Uremic Syndrome Outbreak in Adults and Shiga Toxin-Producing Escherichia coli Negative for Locus of Enterocyte Effacement, France, 2025.

In January 2025, the Escherichia coli National Reference Center of France detected an outbreak of hemolytic uremic syndrome (HUS) in adults, caused by Shiga toxin-producing E. coli negative for locus of enterocyte effacement (LEE). The outbreak included 18 confirmed cases of E. coli infection, 5 probable or possible cases detected by in-house specific PCR, and 2 additional cases from Scotland and Belgium. Whole-genome sequencing identified the outbreak strain as O77 g:K92:H18, belonging to phylogroup D; the strain harbored the Shiga toxin 2 gene variant stx2d-073-C165-02 and a 134-kb plasmid with enterotoxin genes (estb-STb2 and eltAB). Epidemiologic investigation implicated raw-milk cheese as the contamination source. The strain represents a singular hybrid pathotype of Shiga toxin-producing and enterotoxigenic E. coli, expressing a K92 capsule with known cross-immunogenicity to Neisseria meningitidis group C, which could explain the absence of pediatric cases. Related strains have been identified in international databases since 2005, suggesting global emergence.