Cellulosimicrobium Sepsis: Identification of an Emerging Pathogen Using Whole-Genome Sequencing

Cellulosimicrobium is an emerging but still rare pathogen that has exhibited a predilection for immunocompromised patients and those with indwelling medical devices. A case of an immunocompetent 89-year-old man with a history of hypertension who presented with 1 day of subjective fever and right-sided flank pain and was found to be bacteremic secondary to cholecystitis is presented in the present study. Piperacillin-tazobactam was initiated, and a percutaneous cholecystostomy tube was placed the following day. The blood-cultured pathogen was originally identified as Cellulomonas, but whole-genome sequencing (WGS) was used to reidentify the organism as a new clade of Cellulosimicrobium. The patient successfully completed treatment with piperacillin-tazobactam, which resulted in clinical improvement and cholecystostomy tube removal. Therefore, this case highlights the need for accurate microbial identification and the potential of WGS in distinguishing between closely related species to diagnose and treat patients appropriately. Despite its promise, barriers to widespread WGS use include cost and turnaround time, highlighting the need for advances to fully integrate this technology into routine clinical practice.