[Lung diseases due to opportunistic environmental Mycobacteria in patients uninfected with human immunodeficiency virus. Risk factors, clinical and diagnostic aspects and course].

Diseases caused by opportunistic ambient mycobacteria (OAM) are common in HIV-positive patients, although they also occur in immunocompetent individuals. The objective of the present study was to describe the risk factors, clinical signs, course and microbiological spectrum of OAM that cause pulmonary diseases in non HIV-infected individuals in our community. We reviewed 29 consecutive patients with OAM-caused pulmonary disease between 1989-1994 (26 men and 3 women, mean age 58 +/- 14 years). Infections were by Mycobacterium kansasii, 19 (66%) cases; M. avium complex, 7 (24%) cases; M. chelonei, 2 (7%) cases, and M. flavescens, one (3%) case. Risk factors most often associated to infection were smoking and a history of pulmonary disease (chronic obstructive pulmonary disease or residual tuberculosis). Clinical signs were non specific, although toxic syndrome and unproductive cough predominated. Chest films were indistinguishable from those for infection by M. tuberculosis, with cavitated alveolar fibrosis being the main pattern. In vitro drug sensitivity tests showed that all strains were resistant to isoniazid, and that M. avium complex and M. chelonei strains were resistant to rifampicin, streptomycin and, to a lesser degree, to ethambutol. With prolonged medical treatment lasting from 12 to 24 months with first line drugs, outcome was good for the 17 patients for whom full follow-up information was available. Therapy failed to eradicate the bacteria in only 2 patients.