Haemolytic Uraemic Syndrome Triggered by Non-Shiga Toxin-Producing Enteropathogenic Escherichia coli in a Child: Difficulties in Diagnosis and Treatment

Haemolytic uraemic syndrome (HUS) is an important cause of acute kidney injury (AKI) in children, most commonly triggered by Shiga toxin-producing <i>Escherichia coli</i> (STEC). In contrast, HUS associated with non-Shiga toxin-producing enteropathogenic <i>E. coli</i> (EPEC) is rare, particularly when accompanied by neurological involvement. Optimal management in such cases remains uncertain, especially concerning the role of complement inhibition. A previously healthy three-year-old boy presented with bloody diarrhoea, abdominal pain, and fever. He developed biochemical features of HUS and neurological manifestations, including haemiparesis and seizures. Microbiological testing revealed an EPEC strain positive for the <i>eae</i> gene but negative for Shiga toxin. Despite the absence of complement gene pathogenic variants, treatment with plasma exchange (PLEX) and eculizumab (ECZ) was initiated due to rapid clinical deterioration. The patient achieved complete recovery of renal, haematological, and neurological function. Genetic analysis identified variants of uncertain significance, and ECZ discontinuation is being cautiously approached with extended dosing intervals. Although ECZ is well established in complement-mediated HUS, its use in infection-associated HUS is controversial due to limited high-quality trial data. Nevertheless, emerging evidence and case reports suggest that complement activation may play a role in the pathogenesis of unusual forms. This case highlights the potential benefit of early complement inhibition in severe EPEC-associated HUS with neurological complications. This case expands the spectrum of infectious triggers associated with HUS and supports a potential role for complement inhibition in selected cases of infection-associated disease, even without proven complement dysregulation. A personalised approach is vital in managing complex presentations. Further research is required to clarify treatment strategies and identify biomarkers predictive of therapeutic response.