Nontuberculous Mycobacterial Infective Endocarditis: A Systematic Review of Clinical Characteristics and Outcomes

Background: Infective endocarditis (IE) due to nontuberculous mycobacteria (NTM) is a rare infection, and several outbreaks have been reported in the last 2 decades. However, the clinical spectrum is still poorly understood. This systematic review aimed to evaluate the clinical characteristics and outcomes in NTM IE.

Methods: We searched the major electronic databases (PubMed, Scopus, and Google Scholar) with appropriate keywords to December 2023. We included studies based on predefined diagnostic criteria, and relevant data were collected on clinical presentation and treatment outcomes. The study was registered with PROSPERO (CRD42023492577).

Results: A total of 97 studies were reviewed, encompassing 167 patients with NTM IE. The earliest cases were reported in 1975, involving M chelonae and M fortuitum. M chimaera was the most prevalent species (38.9%), though rapidly growing NTM (RGM) were more common than slow-growing NTM (SGM; 59.3% vs 40.7%). Disseminated NTM infection occurred in 84% of cases, with bone marrow infiltration and osteomyelitis as frequent manifestations. Prosthetic valves were the main risk factor, present in 63.5% of cases. In native valve IE, nearly all cases (n = 27, 96%) were attributed to RGM. The overall mortality rate was 44.9%, with conservative management without surgery associated with poorer outcomes (66.7% vs 30.6%). Mortality was comparable between SGM and RGM IE, although relapses were more common in SGM IE (17.6% vs 1.9%).

Conclusions: This review highlights the changing epidemiology of NTM IE with the emergence of RGM IE. Disseminated infections in the setting of prosthetic valves warrant NTM evaluation. The high mortality rate necessitates the role of early surgery.