Urethrocutaneous fistula and subcutaneous abscess in the inguinal region with bacteremia caused by Bilophila wadsworthia in a Japanese patient: A case report

<i>Bilophila wadsworthia</i> is an anaerobic, gram-negative bacillus commonly associated with acute appendicitis. However, bacteremia is exceedingly rare. Herein, we report a case of <i>B. wadsworthia</i> bacteremia associated with a urethrocutaneous fistula and a subcutaneous abscess in the left inguinal region. A 75-year-old man was referred to our hospital due to persistent fever despite piperacillin treatment. The patient was diagnosed with a urethrocutaneous fistula and a subcutaneous abscess in the left inguinal region. <i>B. wadsworthia</i> was isolated from his blood culture and identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry. Subsequently, the patient underwent a four-week course of piperacillin-tazobactam therapy. Since a susceptibility breakpoint has not been established for <i>B. wadsworthia</i>, standardized treatment guidelines are currently unavailable. This case represents the first successful treatment of <i>B. wadsworthia</i> bacteremia with piperacillin-tazobactam, suggesting it may be an effective therapeutic option for infections caused by <i>B. wadsworthia</i>.