Necrotizing pneumonia in a patient with untreated Mycobacterium kansasii infection

Mycobacterium kansasii is the second most commonly occurring Non-Tuberculous Mycobacteria (NTM) in the United States. Infection is typically seen in middle aged males, and the risk of infection is greatly increased in immunocompromised hosts. Pulmonary infection presents in clinical parallel to that of Mycobaterium tuberculosis (TB) and is therefore often misdiagnosed. A combination of clinical, radiological, and microbiological evidence of infection is generally required to clinch the diagnosis. Treatment of such cases include prolonged courses of rifampin in combination with 2 other antimicrobial agents. The overall prognosis with appropriate treatment is good with the exception of disseminated disease in severely immunocompromised hosts. In patients who are misdiagnosed or undertreated, there is progressive destruction of the lung parenchyma with distortion of lung architecture. This can in-turn lead to bronchiectatic changes leaving the airways exposed to devastating superimposed bacterial pneumonia. We describe a case of a patient with untreated M. kansasii infection who developed superimposed necrotizing pneumonia and respiratory failure requiring prolonged ventilatory support.