Medication Summary
The 2007 ATS/IDSA guideline for the treatment of M kansasii pulmonary disease recommends a regimen containing rifampin (600 mg), ethambutol (15 mg/kg) and isoniazid (300 mg) with pyridoxine (50 mg) daily for a total duration that includes at least 12 months of negative sputum culture results. [24]
Patients who are infected with rifampin-resistant M kansasii or who are intolerant of rifampin should be treated with a 3-drug regimen based on susceptibility results. For example, for rifampin-resistant M kansasii, rifampin should be substituted with clarithromycin.
Other agents with useful activity against M kansasii include fluoroquinolones (moxifloxacin, sparfloxacin), aminoglycosides (streptomycin, amikacin), sulfamethoxazole, bedaquiline, and oxazolidinones (tedizolid or linezolid). [24, 29, 30] However, clinical experience for their use in the treatment of M kansasii infection are very limited.
Patients with severe M kansasii infections and disseminated infections should also be treated with 3-drug regimens similar to that instituted for pulmonary infection . Rifampin should not be used concurrently with HIV protease inhibitors or nonnucleoside reverse transcriptase inhibitors (NNRTIs) because rifampin significantly enhances their metabolism. Rifabutin at a lower dose (150 mg/d) should be substituted for rifampin in patients receiving protease inhibitors.
Most M kansasii isolates are pyrazinamide-resistant in vitro. Pyrazinamide is unacceptable as an alternative drug for M kansasii infection.
Antibiotics
Class Summary
Empiric antimicrobial therapy must be comprehensive and should cover all likely pathogens in the context of the clinical setting.
Rifampin (Rifadin, Rimactane)
Considered the most important drug. Inhibits DNA-dependent bacterial but not mammalian RNA polymerase. Cross-resistance may occur. Treat for 6-9 mo or until 6 mo have elapsed from conversion to sputum culture negativity.
Ethambutol (Myambutol)
Impairs cell metabolism by inhibiting synthesis of 1 or more metabolites, which in turn, causes cell death. No cross-resistance demonstrated.
Mycobacterial resistance is frequent with previous therapy. Use in combination with second-line drugs that have not been administered previously.
Administer q24h until permanent bacteriologic conversion and maximal clinical improvement are observed. Absorption is not significantly altered by food.
Isoniazid (INH, Laniazid)
Best combination of effectiveness, low cost, and minor adverse effects. First-line drug unless known resistance or another contraindication is present. Therapeutic regimens of < 6 mo demonstrate unacceptably high relapse rate.
Coadministration of pyridoxine is recommended if peripheral neuropathies secondary to INH therapy develop. Prophylactic doses of 6-50 mg of pyridoxine daily are recommended.
Rifabutin (Mycobutin)
Ansamycin antibiotic derived from rifamycin S. Inhibits DNA-dependent RNA polymerase, preventing chain initiation, in susceptible strains of Escherichia coli and Bacillus subtilis but not in mammalian cells. If GI upset occurs, administer dose bid with food.
Clarithromycin (Biaxin)
Inhibits bacterial growth, possibly by blocking dissociation of peptidyl tRNA from ribosomes, causing RNA-dependent protein synthesis to arrest.
Azithromycin (Zithromax, Zmax)
Macrolide that inhibits bacterial growth, possibly by blocking dissociation of peptidyl tRNA from ribosomes, causing RNA-dependent protein synthesis to arrest. Used once daily as an alternative to clarithromycin.
Streptomycin
Recommended by some experts during the initial phase, especially with positive sputum smear results and positive blood cultures. For treatment of susceptible mycobacterial infections.
Use in combination with other antituberculous drugs (eg, INH, EMB, rifampin).
Amikacin (Amikin)
Occasionally necessary during initial treatment phase, especially with positive sputum smear results. Irreversibly binds to 30S subunit of bacterial ribosomes. Blocks recognition step in protein synthesis. Causes growth inhibition. Use patient's IBW for dosage calculation.
Moxifloxacin (Avelox)
Inhibits bacterial DNA synthesis and growth. Activity is similar to that of ciprofloxacin and levofloxacin.
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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.
