A 41 year‐old man with a past medical history of AIDS CD4 count of 2 cells/ml was found in the subway complaining of generalized weakness and a tender lesion on his left leg. He denied recent trauma, insect bites or exposure to seawater or animals. His only recent travel was to Boston and he denied taking medications. On presentation, he was febrile to 100.3F, HR 118 bpm, BP 89/57. The examination was significant for cachexia, oral thrush and 5 x3 cm erythematous and indurated nodule of the left shin. Incision and drainage was performed by the ED. Laboratory data was significant for a white blood cell count 7.7 k/uL, 94% neutrophils, hemoglobin 8 g/dL and serum albumin 1.6 g/dL. A tibia‐fibula X‐ray showed diffuse soft tissue swelling with obscuration of muscle planes. A noncontrast chest CT revealed a thick walled right upper lobe cavitary lesion, bilateral pulmonary nodules and mediastinal lymphadenopathy. The patient was placed on airborne precautions and started on vancomycin and cefepime for a presumptive bacterial abscess. On the second hospital day, the wound culture reported 4+ AFB seen on direct smear by fluorescence microscopy and later grew Mycobacterium kansasii. The patient was initiated on HAART and empiric treatment with isoniazid, ethambutol, rifabutin. Unfortunately, he was not compliant with the medications and refused additional testing. Two weeks after admission, the patient was found unresponsive and resuscitation efforts were unsuccessful. His family declined our request for an autopsy.
Mycobacterium kansasii is the second most common non‐tuberculous opportunistic mycobacterium infection associated with AIDS. It is not readily isolated from the environment and is presumably acquired via aspiration or local inoculation. Asymptomatic infection is uncommon and rarely is M kansasii considered a colonizer or contaminant. M kansasii infection commonly presents as a chronic pulmonary infection resembling pulmonary tuberculosis. As seen with our case, approximately 90% will have cavitary infiltrates on chest radiography—typically in the right apex. The spectrum of disease includes meningitis, bacteremia, pericarditis, oral ulcers, chronic sinusitis and osteomyelitis. With skin inoculation, M kansasii can cause local disease including cellulitis, nodules, pustules, verrucous lesions, erythematous plaques, seromas or progress to disseminated disease. Twenty percent of HIV infected patients will develop disseminated disease. Treatment is advised when M kansasii is isolated, typically with a 3 drug regimen. The prognosis of disseminated infection is poor, with the presence of immune suppression serving as the best predictor of outcome.
Our case highlights the prevalence of non‐tuberculous mycobacterial infections in the immunocompromised patient and urges an expedited workup for disseminated infection when M kansasii is recovered.