Abstract
We compared the clinical findings and survival in patients with Mycobacterium avium complex (MAC) and other non-tuberculous mycobacteria (NTM). A total of 167 adult non-human immunodeficiency virus (HIV) patients with at least one positive culture for NTM were included. Medical records were reviewed. The patients were categorised according to the 2007 American Thoracic Society (ATS) criteria. MAC comprised 59 % of all NTM findings. MAC patients were more often female (70 % vs. 34 %, p < 0.001) and had less fatal underlying diseases (23 % vs. 47 %, p = 0.001) as compared to other NTM patients. Symptoms compatible with NTM infection had lasted for less than a year in 34 % of MAC patients but in 54 % of other NTM patients (p = 0.037). Pulmonary MAC patients had a significantly lower risk of death compared to pulmonary other NTM (hazard ratio [HR] 0.50, 95 % confidence interval [CI] 0.33–0.77, p = 0.002) or subgroup of other slowly growing NTM (HR 0.55, 95 % CI 0.31–0.99, p = 0.048) or as rapidly growing NTM (HR 0.47, 95 % CI 0.25–0.87, p = 0.02). The median survival time was 13.0 years (95 % CI 5.9–20.1) for pulmonary MAC but 4.6 years (95 % CI 3.4–5.9) for pulmonary other NTM. Serious underlying diseases (HR 3.21, 95 % CI 2.05–5.01, p < 0.001) and age (HR 1.07, 95 % CI 1.04–1.09, p < 0.001) were the significant predictors of mortality and female sex was a predictor of survival (HR 0.38, 95 % CI 0.24–0.59, p < 0.001) in the multivariate analysis. Pulmonary MAC patients had better prognosis than pulmonary other NTM patients. The symptom onset suggests a fairly rapid disease course.
Highlights
The incidence of non-tuberculous mycobacteria (NTM) in clinical samples has been reported to increase, and they have become a more common finding than classical Mycobacterium tuberculosis in many countries [1,2,3]
Samples for mycobacterial culture were analysed by the Central Microbiological Laboratory of Helsinki City, later Helsinki University Central Hospital Laboratory (HUSLAB), and patients were identified and matched with their records and isolates by using their unique personal identity number; these numbers are given to all residents of Finland
The radiological findings of chest X-ray, computed tomography (CT) scans and high-resolution computed tomography (HRCT) were collected from the original radiologist statements at patient visits closest (6 months) to 1 year after the positive culture and classified as infiltrates, nodules, cavities or bronchiectasis according to the 2007 American Thoracic Society (ATS) criteria [17]
Summary
The incidence of non-tuberculous mycobacteria (NTM) in clinical samples has been reported to increase, and they have become a more common finding than classical Mycobacterium tuberculosis in many countries [1,2,3]. M. avium complex (MAC) has been the most commonly found NTM in human infections in most parts of the world, but in Europe, it makes up only about one-third of NTM isolations [3,4,5,6]. In Europe, M. gordonae consisted of up to 17 %, rapidly growing mycobacteria (RGM) 16 %, M. xenopi 14 % and M. malmoense 1 % of all NTM isolations in 2008 [6]. In other parts of the world, M. kansasii, M. abscessus and M. chelonae have been common isolations and, especially in Asia, RGM have been commonly reported [4,5,6]. NTM have been reported to be associated with an increased proportion of deaths in USA and increased risk of respiratory failure [15, 16]
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