**Notes/thanks/other declarations**

The authors would like to acknowledge the Central Tuberculosis Laboratory, Department of Microbiology, Singapore General Hospital, for the contribution of Singapore NTM registry. The authors would like to thank the advices and help from A/Prof. Koh Tse Hsien (Department of Microbiology, Singapore General Hospital), A/Prof. Sng Li-Hwei (Central Tuberculosis Laboratory, Singapore General Hospital), A/Prof. Tan Thuan Tong (Department of Infectious Diseases, Singapore General Hospital), A/Prof. Timothy Mark Sebsatian Barkham (Laboratory Medicine, Tan Tock Seng Hospital) and the support of funding from NMRC/TCR/002-SERI/2012/R1018.
