Article in Japanese

A case of Shiga toxin-producing Escherichia coli O157-associated hemolytic uremic syndrome lacking diarrhea or bloody stool

Yusuke TAKASE^1）, Koji HATACHI^1）, Kunio HASHIMOTO^1）, Toshihiko SHIRAKAWA^1）, Yumiko NAKASHIMA^1）, Yasutomo FUNAKOSHI^1）, Hiroyuki MORIUCHI^1）

Shiga toxin-producing Escherichia coli-associated hemolytic uremic syndrome (STEC-HUS) is the most frequent cause of thrombotic microangiopathy (TMA) in children. It is preceded by STEC enteritis in which bloody stool is a common symptom, especially in cases of O157 infection. This study reports the case of an 8-year-old girl who developed O157 STEC-HUS in the absence of diarrhea or bloody stool. Five days after the onset of fever and lumbago, she developed hemolytic anemia, thrombocytopenia, and renal dysfunction. As she had no defecation, stool specimens were not available for diagnosing STEC-HUS. In addition, her family history prompted thought as to possible rare genetic causes of TMA, which require specific treatment options. Thus, an enema was performed to obtain stool specimens on the fifth day of admission. A stool culture did not yield STEC, and STEC antigen tests were negative;however, the stool
specimen was positive for Shiga (Vero) toxin. Furthermore, serological tests confirmed preceding STEC O157 infection. STEC-HUS should be considered even in the absence of diarrhea and bloody stool, which are indicative of preceding STEC infection. In such
cases, it is difficult to distinguish the underlying causes of TMA based on demographic characteristics and routine blood tests. Rapid STEC tests using stool specimens should be prioritized for differential diagnosis；however, false negative results are common, which make clinical decisions difficult. The serological examination for detecting antibodies to E. coli O antigens is useful and complementary to the rapid antigen tests for diagnosing STEC-HUS.

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1）Department of Pediatrics, Nagasaki University Hospital

Key words	Shiga toxin-producing Escherichia coli, O157, hemolytic uremic syndrome, thrombotic microangiopathy, serological test
Received	April 2, 2021
Accepted	September 6, 2021

33 (4)：359─366,2021