Probiotics-related Clostridium butyricum bacteraemia after COVID-19, confirmed by whole-genome sequencing.

A man in his 70s was admitted to an intensive care unit with severe COVID-19 and treated with dexamethasone and tocilizumab. After recovery from COVID-19, he developed Clostridium butyricum bacteraemia and non-occlusive mesenteric ischaemia, with fatal outcome. He had been prescribed C. butyricum MIYAIRI 588 fine granules as probiotics for a month. The genome sequences of the C. butyricum isolate from the blood culture and C. butyricum MIYAIRI 588 fine granules were identical by single nucleotide polymorphism analysis. This is the first case of definitive probiotics-related C. butyricum bacteraemia after treatment of severe COVID-19.