We report a case of Bacillus subtilis variant natto bacteremia from a gastrointestinal perforation in a patient who ingested natto. Genotypic methods showed the bacteria in a blood sample and the ingested natto were the same strains. Older or immunocompromised patients could be at risk for bacteremia from ingesting natto.
Bacillus subtilis is a gram-positive, rod-shaped, spore-forming bacterium with low pathogenicity (1). B. subtilis isolated from clinical specimens is sometimes considered a contaminant (2). However, a few cases of bacteremia caused by B. subtilis have been reported in Japan (3–6). We report a case of B. subtilis variant natto bacteremia and peritonitis caused by ingestion of natto, a traditional fermented food in Japan that is prepared by adding B. subtilis var. natto culture to soybeans and fermenting them.
A 65-year-old man with metastatic colorectal cancer was admitted to Oita University Hospital (Oita, Japan) with fever and perianal pain. Approximately 2 months before admission, he began chemotherapy with bevacizumab and modified oxaliplatin plus leucovorin plus 5-fluorouracilm (FOLFOX6). Six days before admission, on day 4 after the third course of chemotherapy, he experienced perianal pain. He had a history of diabetes mellitus and a custom of eating natto.
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