O80:H2-Associated Hemolytic Uremic Syndrome without Hemorrhagic Colitis: A Case Report.

Introduction: Hemolytic uremic syndrome (HUS) is characterized by progressive kidney injury accompanied by thrombotic microangiopathy, which is clinically defined as microangiopathic hemolytic anemia with thrombocytopenia and organ injury. Shiga toxin-producing Escherichia coli (STEC)-HUS is caused by infection with pathogenic E. coli strains, typically O157, O26, and O111. However, the prevalence of other types of pathogenic E. coli has been increasing, and these pathogens sometimes cause atypical clinical manifestations of STEC-HUS.

Case presentation: We report the case of a 3-year-old girl diagnosed with STEC-HUS associated with a rare O80:H2 stx2 serotype, characterized by an atypical clinical course. She presented with severe hemolytic anemia and mild renal dysfunction but did not have enterohemorrhagic diarrhea. The first culture test of her stool sample collected using a swab upon admission yielded no signs of STEC, leading to an initial diagnosis of atypical HUS; thus, eculizumab was administered adding to red blood cell transfusion and recombinant thrombomodulin alfa and haptoglobin. However, a subsequent culture test of her second stool sample revealed the presence of O80:H2 stx2, confirming the diagnosis of STEC-HUS. Subsequently, the patient's condition improved, and her serum creatinine level gradually normalized over the course of 3 months.

Conclusion: Diligently diagnosis is crucial in cases lacking typical STEC-HUS symptoms. We advocate for repeated stool culture testing to ensure accurate identification and timely management of such cases.