Mycobacterium conceptionense Bloodstream Infection in a Patient with Advanced Gastric Carcinoma

A 65-year-old Japanese male farmer with advanced gastric adenocarcinoma and multiple hepatic metastases was admitted to our hospital. Blood culture results were positive on day 5, and Gram-positive rods were detected. According to the results of Ziehl-Neelsen staining and a cultured colony of this bacterium, we suspected a mycobacterial infection. Suspecting a rapidly growing mycobacterium (RGM), we started multidrug therapy with levofloxacin, clarithromycin, and ethambutol, and the patient recovered from the bloodstream infection. Further gene examination (16S rRNA, hsp65, and sodA) revealed an isolate of Mycobacterium conceptionense. M. conceptionense was first identified as an RGM in 2006. Among previous case reports of M. conceptionense infections, bone and soft tissue infections in hosts with a disorder of the normal structure (e.g., surgical sites) were dominant. We report the characteristics of M. conceptionense infection in this first Japanese case report and a review of the literature.