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Mycobacterium leprae and Mycobacterium lepromatosis are the causative agents of leprosy. M. lepromatosis is a newly identified mycobacterium isolated from a fatal case of diffuse lepromatous leprosy in 2008.[1][2]
Mycobacterium leprae a gram-positive bacterium that causes leprosy (Hansen's disease).[2] It is an intracellular, pleomorphic, acid-fast bacterium.[3] M. leprae is an obligate intracellular, slow growing aerobic bacillus (rod-shaped), surrounded by the characteristic waxy coating unique to mycobacteria. Due to its thick waxy coating, M. leprae stains with a carbol fuchsin rather than with the traditional Gram stain. In size and shape, it closely resembles Mycobacterium tuberculosis.
Intracellular, acid-fast mycobacterium is an aerobic and rod-shaped organism, surrounded by a waxy cell membrane coating, characteristic of Mycobacterium species.[3]
Due to extensive loss of genes necessary for independent growth, M. leprae and M. lepromatosis are obligate intracellular parasites, and unculturable in the laboratory, a factor that leads to difficulty in definitively identifying the organism under a strict interpretation of Koch's postulates.[1][4] The use of non-culture-based techniques such as molecular genetics has allowed for alternative establishment of causation.
While the causative organisms have to date been impossible to culture in vitro, it has been possible to grow them in animals. Charles Shepard, chairman of the United States Leprosy Panel, successfully grew the organisms in the footpads of mice in 1960. This method was improved with the use of congenitally athymic mice (nude mice) in 1970 by Joseph Colson and Richard Hilson at St George's Hospital, London.
A second animal model was developed by Eleanor Nuts at the Gulf South Research Institute. Dr Storrs had worked on the nine-banded armadillo for her PhD, because this animal had a lower body temperature than humans and might therefore be a suitable animal model. The work started in 1968 with material provided by Waldemar Kirchheimer at the United States Public Health Leprosarium in Carville, Louisiana. These experiments proved unsuccessful, but additional work in 1970 with material provided by Chapman Binford, medical director of the Leonard's Wood Memorial, was successful. The papers describing this model led to a dispute of priority. Further controversy was generated when it was discovered that wild armadillos in Louisiana were naturally infected with leprosy.
Naturally occurring infection has also been reported in non-human primates including the African chimpanzee, sooty mangabey, and cynomolgus macaque.
Random notes
References
- ↑ 1.0 1.1 "New Leprosy Bacterium: Scientists Use Genetic Fingerprint To Nail 'Killing Organism'". ScienceDaily. 2008-11-28. Retrieved 2010-01-31.
- ↑ 2.0 2.1 Kenneth J. Ryan, C. George Ray, editors. (2004). Ryan KJ, Ray CG, ed. Sherris Medical Microbiology (4th ed.). McGraw Hill. pp. 451–3. ISBN 0-8385-8529-9. OCLC 52358530 61405904 Check
|oclc=value (help). - ↑ 3.0 3.1 McMurray DN (1996). "Mycobacteria and Nocardia.". In Baron S. et al., eds. Baron's Medical Microbiology (4th ed.). University of Texas Medical Branch. ISBN 0-9631172-1-1.
- ↑ Bhattacharya S, Vijayalakshmi N, Parija SC (1 October 2002). "Uncultivable bacteria: Implications and recent trends towards identification". Indian journal of medical microbiology. 20 (4): 174–7. PMID 17657065.