Hemolytic uremic syndrome due to Shiga toxin–producing Escherichia coli and hypocomplementemia with favorable response to eculizumab: a case report

Introduction: Neurologic involvement in hemolytic uremic syndrome related to Shiga toxin–producing Escherichia coli (STEC-HUS) is the main cause of death. In last years has been demonstrated that activation of complement alternative pathway also contributes to organ damage. This finding led to the recognition of decreased C3 levels at admission as a marker of poor prognosis as well as the evaluation of the use of eculizumab in cases with neurologic compromise. Objective: to report a patient with STEC-HUS and hypocomplementemia with neurological involvement treated with eculizumab. Clinical case: A 17-month-old male was admitted due to seizures and anuria for last 24 h with a history of 48 h of bloody diarrhea. He presented a laboratory profile compatible with STEC-HUS and severe hyponatremia, results of brain tomography were normal. Also there was complement activation: C3 73 mg/dl (normal > 90 mg/dL) and C5b-9 778.9 ng/ml (normal 135.8-385.3 ng/ml). Initial treatment includes normal saline solution and anticonvulsants drugs, sodium correction and peritoneal dialysis. On third day of hospitalization, because of progression of the neurologic involvement a dose of eculizumab (300 mg) was given, showing at 24 h a markedly neurologic improvement along with and increasing platelet count and a descending lactic dehydrogenase levels. He was discharged after 14 days in a good condition. Later a STEC O157:H7 infection was confirmed and he also normalized the C3 level. Conclusion: This case shows that decreased C3 level at admission was associated to neurologic involvement and suggests that eculizumab might be a favorable therapeutic option.