First case report of Mycobacterium canariasense native mitral valve endocarditis

Mycobacterium canariasense is a relatively newly discovered, rapidly growing nontuberculous Mycobacterium first described in 17 patients with fever in the Canary Islands, Spain, in 2004. To date, there have been very few case reports in literature, and to our knowledge, infective endocarditis due to M. canariasense has not been reported. In this case report, we present a 33-year-old man who was an intravenous drug user with native mitral valve infective endocarditis caused by M. canariasense after presenting with septic emboli to the toes and kidneys. The rapidly growing mycobacterium isolated from blood culture and valve tissue was identified by 16S rRNA sequencing as M. cosmeticum but was finally identified as M. canariasense by rpoB gene sequencing. The patient underwent mitral valve replacement surgery and received combined antibiotic therapy of intravenous ciprofloxacin, intravenous amikacin, and oral clarithromycin with a successful outcome. This case highlights the importance of molecular identification of nontuberculous Mycobacterium to guide antimicrobial therapy in such serious infections.