Molecular identification of fatal Clostridioides mangenotii bloodstream infection in an immunocompromised patient: A case report

Immunocompromised patients are at increased risk of rare opportunistic and emerging infections that can be difficult to diagnose using conventional methods. Molecular approaches can facilitate the identification of unusual pathogens that warrant further investigation. A 36-year-old woman with metastatic invasive ductal carcinoma who had received broad-spectrum antimicrobials for recurrent febrile neutropenia was acutely admitted to the hospital with fever, tachycardia, and hypotension. Septic workup revealed anaerobic Gram-positive bacilli that could not be identified by Matrix-assisted laser desorption/ionization time-of-flight, whereas the VITEK 2 automated system suggested Clostridioides difficile.Despite broad-spectrum antibiotics targeting presumed clostridial infection, including piperacillin/tazobactam, meropenem, vancomycin, and metronidazole, her condition rapidly deteriorated to septic shock, and she died within 72 hours of its onset. Because of the unusual presentation and discordant microbiological results, 16S ribosomal RNA (rRNA) gene amplification and sequencing were performed. The isolate was provisionally identified as Clostridioides mangenotii. This environmental pathogen is closely related to Clostridioides difficile but has rarely been implicated in human disease. This case highlights the importance of molecular diagnostics in identifying rare invasive pathogens in immunocompromised hosts.