Geographic Distribution of Nontuberculous Mycobacteria Isolated from Clinical Specimens: A Systematic Review

Isolation frequency of nontuberculous mycobacterial (NTM) differs per region. Differences in isolation frequency as well as frequencies in clinical relevance are relevant for daily clinical practice. We conducted a systematic review, searching PubMed to assess these differences. Mycobacterium avium complex (MAC) is the most frequently isolated species and the majority of MAC isolates are causative agents of clinically relevant disease, that is, the patient ultimately meets American Thoracic Society/Infectious Disease Society of America diagnostic criteria for NTM pulmonary disease. Differences in isolation frequency between MAC species are seen in different continents. Another species that shows a remarkable difference in isolation frequency is M. abscessus complex, which is common in Asia and Oceania, in contrast to Europe, North America, and South America. Furthermore, differences in isolation frequency are seen between different continents, and also between regions or cities. These differences might drive local epidemiology of NTM pulmonary disease, and knowledge of the local situation is thus essential for daily clinical practice. To be fully able to assess this problem, larger multicenter studies with uniform microbiological methods are needed.