Non-tuberculous mycobacteria in patients with bronchiectasis

M Wickremasinghe ¹, L J Ozerovitch ¹, G Davies ¹, T Woodhouse ¹, M V Chadwick ¹, S Abdallah ¹, P Shah ¹ and R Wilson ^1*

¹ Royal Brompton Hospital, United Kingdom

^* To whom correspondence should be addressed. E-mail: r.wilson{at}rbh.nthames.nhs.uk.

Accepted 10 September 2005

Abstract

Background: Non-tuberculous mycobacteria (NTM) are ubiquitous environmental organisms. Patients with pre-existing lung damage are susceptible to NTM but their prevalence in bronchiectasis is unknown. Distinguishing between lung colonisation and disease can be difficult.

Methods: A prospective study of 100 bronchiectasis patients to evaluate sputum NTM prevalence, and a retrospective analysis over 11 years of clinical, microbiological, lung function and radiology data of our clinic patients with NTM sputum isolates, was performed.

Results: NTM prevalence in this population of bronchiectatics was 2%. Patients in the retrospective study were defined as bronchiectasis and multiple NTM isolates (n=25), bronchiectasis and single isolates (n=23) and non-bronchiectasis and multiple isolates (n=22). Mycobacterium avium complex (MAC) species predominated in bronchiectasis compared to non-bronchiectasis lung disease (72% vs. 9% p<0.0001). Single isolates were also frequently MAC (45.5%). Multiple isolates in bronchiectasis were more often smear positive on first sample than single isolates (p<0.0001). NTM were identified on routine screening samples or because of suggestive radiology. No particular bronchiectasis aetiology was associated with a NTM. Pseudomonas aeruginosa and Staphylococcus aureus were frequently co-cultured. Six (25%) of multiple NTM patients had cavities of which five were due to MAC. Half of patients with multiple isolates were treated, mostly due to progressive radiology.

Conclusions: NTM are uncommon in non-cystic fibrosis bronchiectasis. Routine screening identifies otherwise unsuspected patients. MAC is the most frequent NTM isolated. Half of patients with multiple isolates were treated, based on progressive radiology.

Keywords: bronchiectasis, lung function, mycobacterium avium complex, non-tuberculous mycobacteria

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