Odoribacter splanchnicus bacteremia: a rare condition associated with intestinal disease

Odoribacter splanchnicus is an anaerobe that normally inhabits the human intestine and rarely causes infections in humans. In recent years, however, three cases of O. splanchnicus bacteremia have been reported. We retrospectively searched our laboratory information system and detected five cases of O. splanchnicus bacteremia in 2014-2024. All cases of O. splanchnicus bacteremia reported to date have been associated with intestinal infection, but our five cases included one associated with decubitus ulcer infection. Antimicrobial susceptibility testing results were available in four of our five cases. O. splanchnicus showed susceptibility to beta-lactams and metronidazole. However, one isolate was resistant to clindamycin, and another showed intermediate susceptibility to levofloxacin. Among our five cases and the three previously reported cases, no patient was using immunosuppressive agents or had immunocompromising diseases except for one case with malignancy. While O. splanchnicus bacteremia is certainly rare, more cases may be found by searching the laboratory information system as in this investigation. Further accumulation of cases will help to elucidate the pathogenesis of infections caused by O. splanchnicus, which is endemic in the gastrointestinal tract, and will reveal more information on antimicrobial susceptibility.