Non-tuberculous pulmonary infections in Scotland: A cluster in Lothian?

Abstract

Background - A retrospective study was carried out to confirm the clinical impression that, in Lothian, non-tuberculous mycobacterial infections are as common as pulmonary tuberculosis. Methods - All pulmonary isolates of Mycobacterium tuberculosis/bovis and non-tuberculous mycobacteria in Scotland from April 1990 to March 1993, and the notes of all patients with M malmoense isolates in Lothian, were reviewed. Information on mycobacterial culture procedures in Scottish laboratories was obtained as part of an audit project. Results - Of all pulmonary isolates of mycobacteria in Lothian 53% (108/205) were non-tuberculous strains compared with 18% (140/800) for Scotland outside Lothian. Although comparable in population size and laboratory techniques, Lothian (108) had almost twice as many isolates of non-tuberculous mycobacteria as Glasgow (56), but the proportions of M malmoense and M avium intracellulare complex were similar in both areas. Of 41 patients with M malmoense isolates in Lothian 30 (75%) had clinically significant lung disease; only one was HIV positive. Conclusions - Non-tuberculous mycobacteria pose an increasing clinical problem in Scotland as a cause of pulmonary disease. There is a cluster of cases with M malmoense infection in Lothian which cannot be attributed to the high local prevalence of HIV.