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. T he role of Mycobacterium kansasii as an infecting organism was not recognised until the early 1950s. M kansasii infection shares many clinical aspects with tuberculosis (TB). However, M kansasii infection contrasts with TB by being non-contagious, more associated with underlying diseases, and having a definite geographical distribution-that is, in southern and central USA.1-4 In a non-endemic area, a higher incidence of M kansasii isolates was found among HIV positive persons, and more predisposing medical conditions were found among HIV negative persons.5 While the prevalence of TB has decreased in the past 20 years, those of non-tuberculous mycobacterial infections including M kansasii have been increasing worldwide. As a positive sputum culture for M kansasii may only reflect colonisation, strict criteria have been developed for the diagnosis of pulmonary M kansasii infection to exclude a mere colonisation. Varying findings on M kansasii pulmonary infection were reported from cancer treatment centres, HIV treatment centres, TB centres, mining company TB clinics, and pulmonary departments. We present here data analysis of the largest patient population with the longest follow up, hopefully to confirm prior findings and to help resolve some of the conflicting conclusions.
METHODSThis is a retrospective study of M kans...