[Pulmonary infection by Mycobacterium kansasii. Presentation of 27 cases (1988-1992)]

The aim of this study was to know the incidence of pulmonary disease by Mycobacterium kansasii in our medium in the general population with a description of the characteristics as well as the subjects which this disease affects. The incidence was related with the isolation of Mycobacterium tuberculosis on consideration of the hospital studied (practically a monography of thoracic diseases).

A retrospective review of the clinical histories of patients with positive cultures of Mycobacterium kansasii in respiratory samples was performed with the criteria of the pulmonary diseases attended in the authors center over the period from January 1988 to December 1992 being defined. A descriptive analysis of the clinical and radiographic variables, treatment and evolution was also carried out.

Mycobacteria was isolated in 1,755 respiratory samples processed by the Laboratory of Microbiology with 95% corresponding to Mycobacterium tuberculosis and 4.5% to non tuberculin mycobacteria. Mycobacterium kansasii made up 83% of the latter (3.7% of global significant isolations). Pulmonary disease by Mycobacterium kansasii was diagnosed in 27 patients (26 males and 1 female) with a mean age of 48 years (range: 24-84 years). No disseminated forms of disease were observed in this series. The sputum demonstrated high diagnostic profitability (positive in 26/27). Clinical and radiological variables were unspecific (only 1 normal) with a high percentage of cavitation being observed (74%). Most were carriers of chronic and/or general pulmonary diseases. The evolution was favorable in 70.3% of the cases with 3 patients dying (11.1%), all with severe subjacent disease and one of a cause not related with the infection. Three recurrences were observed (11.1%) and 2 persistence of positive culture (7.4%). One of the strains was niacin positive (expectional feature).

Mycobacterium kansasii is not a rare producer of disease in our medium in the general population being found in 3.7% of the total significant isolations of mycobacteria in respiratory samples in the authors center over the period from 1988 to 1992. It was found to be associated to pulmonary or general subjacent diseases preferable affecting middle-aged males. The clinical are radiological features were not specific with a high percentage of cavitation being observed. No disseminated disease was found. Conventional combined chemotherapy was effective with persistence and recurrence being seen in 11% and 7%, respectively. The prognosis of the disease was primarily determined by the basal situation of the host.