Mycobacterium kansasii
| Mycobacterium kansasii | ||||||||||||||
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| Mycobacterium kansasii Hauduroy 1955, ATCC 12478 |
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Overview
Mycobacterium kansasii
Description
Gram-positive, nonmotile, moderately long to long and acid-fast rods.
Colony characteristics
- Smooth to rough colonies after 7 or more days of incubation.
- Colonies grown in dark are nonpigmented, when grown in light or when young colonies are exposed briefly to light, colonies become brilliant yellow (photochromogenic).
- If grown in a lighted incubator, most strains form dark red crystals of β-carotene on the surface and inside of colony.
Physiology
- Growth on Middlebrook 7H10 agar at 37°C within 7 days or more.
- Resistant to isoniazid.
- Susceptible to ethambutol.
Differential characteristics
- Closely related to the non-pathogenic, also slowly growing, nonpigmented M. gastri.
- Both species share an identical 16S rDNA but differentiation is possible by differences in the ITS and hsp65 sequences
- A commercial hybridisation assay (AccuProbe) to identify M. kansasii exists.
Pathogenesis
- Chronic human pulmonary disease resembling tuberculosis (involvement of the upper lobe).
- Extrapulmonary infections, (cervical lymphadenitis in children, cutaneous and soft tissues infections and musculoskeletal system involvement), are uncommon.
- Rarely causes disseminated disease except in patients with severely impaired cellular immunity (patients with organ transplants or AIDS).
- Normally considered not to be contagious from person to person.
- Natural sources of infections unclear. Tap water is believed to be the major reservoir associated with human disease.
- Biosafety level 2
Type Strain
- First and most frequently isolated from human pulmonary secretions and lesions.
Strain ATCC 12478 = CIP 104589 = DSM 44162 = JCM 6379 = NCTC 13024.
Treatment
Antimicrobial regimen
- pulmonary disease
- Preferred regimen: Rifampin 10 mg/kg/day (maximum, 600 mg) AND Ethambutol 15 mg/kg/ day AND Isoniazid 5 mg/kg/day (maximum 300 mg) AND Pyridoxine 50 mg/day
- NOTE: Treatment duration for M. kansasii lung disease should include 12 months of negative sputum cultures
- Rifampin-resistant M. kansasii disease
- Preferred regimen: Use three-drug regimen include Clarithromycin OR Azithromycin OR Moxifloxacin OR Ethambutol OR Sulfamethoxazole OR Streptomycin
- NOTE: Patients undergoing therapy for M. kansasii lung disease should have close clinical monitoring with frequent sputum examinations for mycobacterial culture throughout therapy
References
- Hauduroy,P. 1955. Derniers aspects du monde des mycobactéries. Masson et Cie, Paris, 1955.