The clinical manifestations include both indolent or rapidly progressive disease. Clinical data suggest that patients do better with earlier therapy. Mycobacterium kansasii isolated from respiratory cultures is generally regarded as a pathogen. Culture techniques and drug susceptibility testing similar to that used with Mycobacterium tuberculosis , can also be performed in patients with Mycobacterium kansasii infection. The rapidly growing mycobacteria cause disease more commonly than was previously thought.
Cutaneous manifestations predominate.
Most cases are sporadic and community-acquired, although nosocomial cases have also been reported. Most patients are white women with no underlying lung disease and unrelated to smoking. The disease runs a slowly progressive course unless successfully treated. Mycobacterium scrofulaceum usually causes disease in children 1 to 5 years of age, with unilateral involvement of the submandibular, submaxillary, and cervical lymph nodes . Patients are mildly symptomatic, manifesting only minimal constitutional features such as low-grade fever.