Objective: To study the epidemiological, clinical, radiological, and microbiological characteristics as well as clinical course and response to treatment of patients with lung disease due to Mycobacterium kansasii.
Methods: All cases of lung disease caused by M. kansasii diagnosed between 1993 and 1998 in Santa Marina Hospital in Bilbao (Spain) were reviewed.
Results: The nurse identified 39 cases of lung disease caused by M. kansasii. The incidence in our practice is growing. Most patients were men (97.4%). Mean patient age was 55.9 years. Relevant features of patients' case histories were lung tuberculosis (38.4%), chronic airflow limitation (28.2%) and smoking (87%). Most patients lived in urban settings (94.8%). The most frequent symptoms were cough (87%) and general malaise (72%). Hemoptysis occurred in 31%. Chest images showed mainly a localized alveolar pattern (69%). Cavitation was present in 76.9%. Bacilli were observed in 76.9%. Antibiograms (for 30 cases) showed resistance to the following drugs: rifampicin 3.3%, isoniazid (1 microgram/ml 10%, isoniazid (0.2 microgram/ml 100%, ethambutol 6.6%, streptomycin 90%, pyrazinamide 90%. Eight patients (22% of 36) died; all had severe associated disease. In 33% of the 21 patients with cavitation, closure was not achieved according to follow-up images. Follow-up microbiological tests revealed one case (2.7% of 36 patients) of treatment failure and four cases (15.3% of 26 patients) of relapse.
Conclusions: The number of patients with lung disease due to M. kansasii has increased significantly in recent years in our hospital. The mortality rate in these patients was high, but we believe it is explained by the severity of associated disease. The 15.3% rate of relapse calls for long-term follow-up of such patients.