PURPOSE: Non-tuberculous mycobacterial (NTM) lung infection often occurs in the setting of underlying structural lung disease, but the role of COPD in NTM pathogenesis has not been well studied. We hypothesized that changes in the airway related to COPD result in increased susceptibility of airway colonization and disease from NTM.
METHODS: Data including microbiology, spirometry, and tobacco abuse history were collected from the medical records of all individuals with a positive respiratory culture for non-tuberculous mycobacteria seen over an 18-month period at a single VA pulmonary subspecialty clinic. Subjects were considered to have clinically significant NTM lung disease if diagnostic criteria were met according to 2007 American Thoracic Society guidelines or if a decision was made to treat.
RESULTS: We identified 80 unique individuals from whom at least one respiratory culture grew non-tuberculous mycobacteria. Cultures from 12 subjects grew more than one NTM species. Mycobacterium avium complex (MAC) and M. kansasii were the most commonly isolated species (31/92, 33.7% and 10/92, 10.9%, respectively). Compared to other species, MAC and M. kansasii were more likely to be isolated from patients with a diagnosis of COPD than from subjects without obstructive lung disease (p= 0.044). Neither the presence nor the severity of COPD was associated with an increased likelihood of having clinically significant NTM disease; however, individuals with severe COPD (GOLD stage III or IV) were significantly more likely to have multiple NTM species grow in culture (p=0.023).
CONCLUSION: Underlying COPD appears to increase susceptibility to airway colonization with NTM but is not associated with an increase in clinically significant NTM lung disease.
CLINICAL IMPLICATIONS: Airway colonization by non-tuberculous mycobacteria may have important effects on airway inflammation and disease progression in patients with COPD.
DISCLOSURE: Julie Philley, No Financial Disclosure Information; No Product/Research Disclosure Information