While the treatment of Mycobacterium tuberculosis is firmly based on multiple controlled clinical trials in various settings1 ,2 and meet the criteria for ‘A’ category recommendations,3 the management of opportunist mycobacteria (mycobacteria other than tuberculosis (MOTT), non-tuberculous mycobacteria, environmental mycobacteria, atypical mycobacteria) is much less so. When the Joint Tuberculosis Committee of the British Thoracic Society reviewed the evidence base for the treatment of this group of organisms in HIV negative persons for their 2000 treatment guidelines,4 only the treatment recommended for M kansasii was based on a prospective controlled study.5 The treatment recommendations for the other common opportunist mycobacteria causing respiratory …