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.
Keywords: Escherichia coli; France; HUS; STEC; Shiga toxin–producing Escherichia coli; bacteria; diarrhea; elderly; enteric infections; hemolytic uremic syndrome; locus of enterocyte effacement; outbreak.