Article in Japanese

Hemolytic-uremic syndrome diagnosed as enterohemorrhagic Escherichia coli O121 infection using a serodiagnostic microagglutination assay: a case report

Satoshi OGASAWARA¹⁾, Yasuko KOBAYASHI¹⁾, Yuka IKEUCHI¹⁾, Chikage YOSHIZAWA¹⁾, Mariko TAKEI¹⁾, Takumi TAKIZAWA¹⁾, Makoto ONISHI²⁾, Hirokazu ARAKAWA¹⁾

Hemolytic-uremic syndrome(HUS) is thrombotic microangiopathy(TMA) characterized by a triad of symptoms: hemolytic anemia, thrombocytopenia, and acute kidney injury. HUS caused by enterohemorrhagic Escherichia coli (EHEC) infection accounts for 64% of TMA developed in Japanese children. EHEC infection is diagnosed by isolating the bacteria from fecal culture and detecting verotoxin from stool or by detecting anti-O antigen antibody from the patient's serum. It is impossible to distinguish EHEC-related HUS from atypical HUS without establishing evidence of EHEC infection.
A 2 year-old boy developed HUS and was hospitalized after having persistent diarrhea for 2 weeks. Hemodialysis was initiated because of sustained oliguria, metabolic acidosis, and hyperkalemia against conservative treatment. From the 4th day of hospitalization, the oliguria improved and the patient was discharged from hospital on the 12th day. HUS caused by EHEC infection was suspected from family history; however, the causative bacteria were not detected via fecal culture, and the O157 lipopolysaccharide antibody test results were negative. This study conducted E. coli O antigen microagglutination assay for differential diagnosis for atypical HUS, or non-O157 EHEC infection. O121 antibody was positive in the serum obtained at the time of admission and discharge from hospital. Therefore, the patient received a diagnosis of HUS caused by EHEC O121 infection.
It is important to diagnose non-O157 EHEC infection as well as O157 infection that causes HUS. The E. coli O antigen agglutination antibody test, using the patient's serum, is useful in HUS cases where EHEC was not detected by fecal culture.

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1) Department of Pediatrics, Gunma University Medical School Hospital
2) Research Bacteria Part 1, National Institute of Infectious Diseases

Key words	hemolytic uremic syndrome, enterohemorrhagic E. coli infection, O 121, E. coli O antigen agglutination antibody test
Received	December 20, 2018
Accepted	April 23, 2019

31 (3)：275─280,2019