Clinical features and follow up of 302 patients with Mycobacterium kansasii pulmonary infection: a 50 year experience.

AIMS: To analyse clinical features and treatment outcomes of patients with pulmonary Mycobacterium kansasii infection treated at Hines VA Hospital between 1952 and 1995, and followed up until 2003.
FINDINGS: 302 patients were confirmed to have M kansasii pulmonary infection; diagnosis was not made until death in 2%. The average age was 50 years old; 76% were white; all were men. Productive cough, dyspnoea, and chest pain were common; 16% were asymptomatic. Right sided, apical or subapical, thin walled cavitary infiltrate was the characteristic radiological feature. Heavy smoking, chronic obstructive pulmonary disease, alcoholism, peptic ulcer disease, coronary artery disease, prior tuberculosis, psychosis, prior pneumonia, and immunocompromising conditions were prevalent. Average follow up was 10 years and 2 months. PPD was positive in 58% of 179 tested. Two thirds of the patients required only first line drugs. Fourteen per cent required surgical intervention, none after 1977. Spontaneous resolution occurred in 1%. Aspergillosis developed in 4%. Bronchogenic carcinoma coexisted with M kansasii infection in 6% and followed it in 4%. Extrapulmonary malignancy coexisted with the infection in 4% and followed it in 6%; most involved head and neck. Eleven per cent of 224 deaths were attributed to M kansasii. Outcomes were affected by comorbidity, treatment compliance, rifampicin use, and extent of infection.
CONCLUSIONS: Prognosis of M kansasii pulmonary infection is good if diagnosed and treated early, together with control of underlying conditions. Clinicians should be aware of atypical radiological manifestations of the disease when coexisting with other pulmonary or immunocompromising conditions.