Characterizing Non-Tuberculous Mycobacteria Infection in Bronchiectasis

Abstract

Chronic airway infection is a key aspect of the pathogenesis of bronchiectasis. A growing interest has been raised on non-tuberculous mycobacteria (NTM) infection. We aimed at describing the clinical characteristics, diagnostic process, therapeutic options and outcomes of bronchiectasis patients with pulmonary NTM (pNTM) disease. This was a prospective, observational study enrolling 261 adult bronchiectasis patients during the stable state at the San Gerardo Hospital, Monza, Italy, from 2012 to 2015. Three groups were identified: pNTM disease; chronic P. aeruginosa infection; chronic infection due to bacteria other than P. aeruginosa. NTM were isolated in 32 (12%) patients, and among them, a diagnosis of pNTM disease was reached in 23 cases. When compared to chronic P. aeruginosa infection, patients with pNTM were more likely to have cylindrical bronchiectasis and a “tree-in-bud” pattern, a history of weight loss, a lower disease severity and a lower number of pulmonary exacerbations. Among pNTM patients who started treatment, 68% showed a radiological improvement, and 37% achieved culture conversion without recurrence, while 21% showed NTM isolation recurrence. NTM isolation seems to be a frequent event in bronchiectasis patients, and few parameters might help to suspect NTM infection. Treatment indications and monitoring still remain an important area for future research.

Bronchiectasis in indigenous and non‐indigenous residents of Australia and New Zealand

“…When performed, the results indicated a low level of NTM with a higher proportion of non‐MAC mycobacteria seen in Aboriginal Australians. This was consistent with previous studies that found NTM isolated in 8–12% of patients and MAC in 4% …”

Geographic variation in the aetiology, epidemiology and microbiology of bronchiectasis

“…Bronchiectasis and NTM are highly associated pulmonary diseases with airway distortion predisposing to NTM infection [79,80]. While NTM is isolated from the bronchiectasis airway and clearly associates with poorer outcomes and more aggressive disease in most cases (largely dependent on the species involved), in some studies, it interestingly has been associated with a milder phenotype, less severe disease, lower exacerbations and better pulmonary function [81,82]. NTM colonisation in common with P. aeruginosa is more frequent in older patients with gender preponderance for postmenopausal women and a lower prevalence is observed in paediatric populations [82][83][84][85].…”

Pathogenesis, imaging and clinical characteristics of CF and non-CF bronchiectasis

“…NTM belonging to the MAC group are also highly prevalent in non-CF bronchiectasis with a female preponderance [35,36]. This group of organisms are surprisingly poorly associated with disease severity and exacerbations in the non-CF setting when compared to Pseudomonas [37,38]. In contrast for CF patients, MAC and M. abscessus are often associated with an aggressive and accelerated lung function decline [39][40][41][42].…”