Health Dictionary
Reliable, easy-to-read patient information on common medical conditions — written in plain language, free of jargon, and grounded in current evidence. Browse the most frequent diagnoses, understand what they mean for everyday life, and learn which steps and questions help you have a focused conversation with your doctor.
M. kansasii
Introduction
Overview
Overview
Mycobacterium kansasii
Description
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
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
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
Treatment
Antimicrobial regimen
- 1. pulmonary disease [1]
- 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
- 2. Rifampin-resistant M. kansasii disease
- Preferred regimen: Use three-drug regimen include Clarithromycin OR Azithromycin OR Moxifloxacin OR Ethambutol OR Sulfamethoxazole OR Streptomycin
- 3. Disseminated M. kansasii disease
- Preferred regimen: The treatment regimen for disseminated disease should be the same as for pulmonary disease
References
References
- ↑ Griffith, David E.; Aksamit, Timothy; Brown-Elliott, Barbara A.; Catanzaro, Antonino; Daley, Charles; Gordin, Fred; Holland, Steven M.; Horsburgh, Robert; Huitt, Gwen; Iademarco, Michael F.; Iseman, Michael; Olivier, Kenneth; Ruoss, Stephen; von Reyn, C. Fordham; Wallace, Richard J.; Winthrop, Kevin; ATS Mycobacterial Diseases Subcommittee; American Thoracic Society; Infectious Disease Society of America (2007-02-15). “An official ATS/IDSA statement: diagnosis, treatment, and prevention of nontuberculous mycobacterial diseases”. American Journal of Respiratory and Critical Care Medicine. 175 (4): 367–416. doi:10.1164/rccm.200604-571ST. ISSN 1073-449X. PMID 17277290.
- Hauduroy,P. 1955. Derniers aspects du monde des mycobactéries. Masson et Cie, Paris, 1955.
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