Background: Pre-existing underlying bronchopulmonary diseases and relative impairments of the immune system are risk factors that predispose to the development of pulmonary infections with non-tuberculous mycobacteria (NTM), even if the impairment is not severe.
Methods: In a prospective study n = 111 patient diagnoses between 1992 and 2004 were included. The criterion for inclusion was laboratory evidence of non-tuberculous mycobacteria. The local risk factors and general risks were recorded for each case and the total number of risks for each patient was counted. Risk profiles were drawn up and risk scores calculated for different groups.
Results: N = 66 patients met the ATS criteria for NTM disease. The disease rates for the most frequent species varied widely ( M. AVIUM complex 57 %, M. KANSASII 100 %, M. XENOPI 73 %). Older women (> 65 years) with M. AVIUM complex were rarely ill. The risk factors were almost equally frequent for patients meeting criteria for disease status and those who did not and patients under 65 years of age had fewer local risk factors than older patients. Patients with M. GORDONAE showed fewer local risk factors than patients with M. AVIUM complex or M. XENOPI.
Conclusions: Even local risk factors predispose towards infections with mycobacteria and do not only lead to disease after infection. Bullous changes of the lungs, cavities and bronchiectasis are local risk factors, but can also develop as sequelae of mycobacteriosis. There is sufficient evidence to support the continued use of the concept of colonisation alongside those of infection with and infection without disease status. In our region, a thorough evaluation is needed to establish whether older women with M. AVIUM complex actually have mycobacteriosis.