From the Guidelines
Mycobacterium kansasii is a slow-growing nontuberculous mycobacterium (NTM) that primarily causes lung disease resembling tuberculosis. It's the second most common cause of NTM lung disease in the United States after Mycobacterium avium complex. M. kansasii typically infects individuals with underlying lung conditions such as COPD, previous tuberculosis, or bronchiectasis, though it can occasionally affect immunocompromised patients or those with no predisposing factors. The standard treatment regimen for M. kansasii infection, as suggested by the most recent guideline 1, consists of rifampicin, ethambutol, and either isoniazid or macrolide for patients with rifampicin-susceptible M. kansasii pulmonary disease. Some key points to consider when treating M. kansasii include:
- Neither parenteral amikacin nor streptomycin are recommended for routine use in these patients 1
- Patients with nodular/bronchiectatic M. kansasii pulmonary disease should receive either daily or three times weekly treatment when receiving a macrolide, rifampicin and ethambutol 1
- In patients with cavitary disease, the regimen should be administered daily 1
- When patients are treated with a regimen that includes isoniazid, ethambutol and rifampicin, treatment should be given daily 1
- In patients with rifampicin-resistant M. kansasii or intolerance to one of the first line antibiotics, a fluoroquinolone (e.g., moxifloxacin) should be used as part of a second-line regimen 1
- All patients should be treated for at least 12 months 1
From the Research
Definition and Characteristics of Mycobacterium kansasii
- Mycobacterium kansasii (M. kansasii) is a non-tuberculosis bacterium that is highly virulent among nontuberculous mycobacteria (NTM) 2.
- It is one of the main species responsible for NTM pulmonary disease, with the ability to cause lung disease (LD) 3.
- M. kansasii is transferred by aerosols from water and soil resources to the respiratory system, with tap water being a major reservoir 4.
Clinical Syndromes and Radiological Findings
- Clinical syndromes and radiological findings of M. kansasii infection are mostly indistinguishable from those of Mycobacterium tuberculosis, requiring microbiological confirmation 4.
- The majority of patients with M. kansasii pulmonary disease have underlying pulmonary comorbidities, such as smoking, chronic obstructive pulmonary disease, bronchiectasis, and prior or concurrent M. tuberculosis infection 4.
- Common sites of extrapulmonary disease include the lymph nodes, skin, and musculoskeletal and genitourinary systems 4.
Treatment and Outcomes
- Treatment of M. kansasii-LD is recommended due to the disease's poor prognosis and fatal outcome, with rifampin-containing multiple antimicrobial regimens being effective for treatment-naïve patients 2.
- The initial treatment involves rifampin, ethambutol, isoniazid, and pyridoxine, per the guidelines from the American Thoracic Society (ATS) and the Infectious Diseases Society of America (IDSA) 3.
- A macrolide-containing regimen appears to be as effective as an isoniazid-containing regimen for treatment of M. kansasii pulmonary disease 5.
- Treatment should be continued until sputum cultures are consecutively negative for at least one year 6.