Population genomics provides insights into the evolution and adaptation to humans of the waterborne pathogen Mycobacterium kansasii

Mycobacterium kansasii can cause serious pulmonary disease. It belongs to a group of closely-related species of non-tuberculous mycobacteria known as the M. kansasii complex (MKC). Here, we report a population genomics analysis of 358 MKC isolates from worldwide water and clinical sources. We find that recombination, likely mediated by distributive conjugative transfer, has contributed to speciation and on-going diversification of the MKC. Our analyses support municipal water as a main source of MKC infections. Furthermore, nearly 80% of the MKC infections are due to closely-related M. kansasii strains, forming a main cluster that apparently originated in the 1900s and subsequently expanded globally. Bioinformatic analyses indicate that several genes involved in metabolism (e.g., maintenance of the methylcitrate cycle), ESX-I secretion, metal ion homeostasis and cell surface remodelling may have contributed to M. kansasii's success and its ongoing adaptation to the human host.Mycobacterium kansasii can cause serious pulmonary disease. Here, the authors present a population genomics analysis of 358 environmental and clinical isolates from around the world, supporting the idea that municipal water is a main source of infection, and shedding light into the pathogen's diversity and adaptation to the human host.

Automated summary

A population genomics analysis of Mycobacterium kansasii reveals municipal water as a main source of infection and shows that nearly 80% of infections are due to closely-related strains, forming a main cluster that originated in the 1900s. Bioinformatic analyses suggest that certain genes may have contributed to the pathogen's success and adaptation to the human host.