History
In most cases, M kansasii causes lung disease that is clinically indistinguishable from tuberculosis. Symptoms may be less severe and more chronic than Mycobacterium tuberculosis infection. Asymptomatic M kansasii infection occurs in a small proportion (16%) of affected patients. [11]
Healthy host
The most common symptoms of pulmonary M kansasii infection include cough (91%), sputum production (85%), weight loss (53%), breathlessness (51%), chest pain (34%), hemoptysis (32%), and fever or sweats (17%). [15]
Cutaneous M kansasii infection resembles sporotrichosis secondary to local lymphatic spread. Cutaneous lesions may include nodules, pustules, verrucous lesions, erythematous plaques, abscesses, and ulcers.
Immunocompromised host
M kansasii infection manifests late in the course of HIV disease. The lung is the organ most commonly involved. Commonly reported symptoms include fever, chills, night sweats, productive or nonproductive cough, weight loss, fatigue, dyspnea, and chest pain.
Almost 20% of patients with HIV infection who develop M kansasii infection eventually develop disseminated disease.
M kansasii meningitis similar to M tuberculosis meningitis has been reported in patients infected with HIV and may carry a higher mortality rate despite appropriate antibiotic therapy.
M kansasii bacteremia, pericarditis with cardiac tamponade, oral ulcers, chronic sinusitis, osteomyelitis, and scalp abscess have been reported in patients with AIDS.
Disseminated M kansasii infection has also been reported in other immunocompromised hosts (eg, patients with myelodysplastic syndrome, patients on hemodialysis).
Cutaneous M kansasii infections in immunocompromised hosts usually have atypical clinical features (eg, cellulitis, seroma). These features, along with atypical histology (eg, absence of granuloma), may delay diagnosis.
Physical
Common physical findings of M kansasii infection include the following:
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Fever
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Pulmonary crackles and wheezing
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Lymphadenopathy
Analysis of a series of 49 patients coinfected with HIV showed the following physical findings at the time of initial isolation of M kansasii: [16]
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Pulmonary disease
Fever (45%)
Lung crackles (40%)
Lymphadenopathy (25%)
Wheezes (20%)
Hepatosplenomegaly (5%)
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Disseminated disease
Fever (60%)
Hepatosplenomegaly (40%)
Lung crackles (25%)
Lymphadenopathy (10%)
Cutaneous lesions (10%)
Wheezes (5%)
Patients with cutaneous M kansasii infection may develop nodules, pustules, verrucous lesions, erythematous plaques, abscesses, or ulcers.
Other signs depend on the site of infection. For example, other manifestations, such as septic arthritis, tenosynovitis, osteomyelitis, and pleurisy, among others, have been reported.
Causes
Immunocompromised patients, including patients with HIV/AIDS, are at a high risk for M kansasii infection.
Predisposing conditions for M kansasii infection include pulmonary conditions resulting from pneumoconioses (especially silicosis, gold mining, and coal mining), healed chronic infections (eg, tuberculosis, mycosis, chronic obstructive pulmonary disease, bronchiectasis), heavy smoking, and chronic obstructive pulmonary disease.
Other risk factors include cancer, diabetes mellitus, long-term steroid use, alcoholism, peptic ulcer disease, coronary artery disease, and prior pneumonia.
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Chest radiograph in a patient with Mycobacterium kansasii pulmonary infection shows left lower lung infiltrates.
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Chest CT scan in a patient with Mycobacterium kansasii pulmonary infection.
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Chest radiograph in a patient with classic right upper lobe cavitary lung disease secondary to Mycobacterium kansasii infection. Courtesy of Raj Sreedhar, MD, SIU School of Medicine, Springfield, IL.
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CT thorax of a patient with classic right upper lobe cavitary lung disease secondary to Mycobacterium kansasii infection. Courtesy of Raj Sreedhar, MD, SIU School of Medicine, Springfield, IL.
