Flavonifractor plautii: A Rare Cause of Anaerobic Bacteremia.

Flavonifractor plautii (formerly Eubacterium plautii) is a Gram-variable, strict anaerobic bacillus that forms part of the human gut microbiome, although its role in human health remains incompletely understood. F. plautii has rarely been linked to clinical infections. We describe a case of bacteremia in a patient with severe intrahepatic biliary ductal dilatation and septic shock and F. plautii bacteremia, which cleared following treatment with ceftriaxone and metronidazole. Diarrhea with disruption of the gut barrier and subsequent bacterial translocation appear to be the mechanism for bacteremia due to this organism. Based on this case and previous reports, F. plautii infections appear susceptible to beta-lactam antibiotics (e.g., ampicillin, ceftriaxone) and anaerobic agents (e.g., metronidazole, clindamycin), supporting their use as preferred treatment options over glycopeptides or oxazolidinones. This case underscores the importance of recognizing anaerobic gut commensals as potential bloodstream pathogens in critically ill patients.