Mycobacterium leprae

Mycobacterium leprae
Scientific classification
Kingdom: Eubacteria Phylum: Actinobacteria Order: Actinomycetales Family: Mycobacteriaceae Genus: Mycobacterium Species: leprae
Binomial name
Mycobacterium leprae

Mycobacterium leprae causes the disease leprosy, also called Hansen's disease after the scientist that discovered the organism in the skin nodules of leprosy patient. For a long time this disease was seen as a curse , an hereditary disease and its patients used to be stimatized. Cases of this disease has been reported as early as 650 BCE and the Christian Bible talks alot about it.But it's not as contagious as the Bible stories make us believed. Patients of this disease used to be stunned. This disease no longer cause a treat to the United States but is a major problems in the third countried specially India, Brazil and some parts of Africa. M.leprae is an obligate parasite that once it atttacks the human body can take a long time to show symptoms.

Genome structure

It was discovered in 1873 by Gerhard Armauer Hansen. He discovered it in the skin nodules of patients with leprosy.

Mycobactrium M.leprae has about 3,268,203 base pairs. Only 49% of the genome encode for proteins. The rest is composed of pseudogenes. In size and shape M.leprae resemble the M. tuberculosis.

Cell structure and metabolism

M. leprae is an aerobic, rod-shaped bacterium, technically Gram-positive but often difficult to stain without an acid-fast procedure such as the Ziehl-Neelsen stain. It is believed that the pseudogenes used to be involved in metabolic patgways but now this bacteria lost its metabolic capability, making it an obligate parasite that depends on its host for most of its nutritional and functional needs.

Mycobacteria have a waxy coating of mycolic acid, which is made up of large lipids that are covalently bonded to each other to form the waxy coating. The coating is solid at room temperature, resisting most disinfectants except those certified as tuberculocides.

Ecology

This bacteria is believed to live in the soil. Scientists think that the reservoir for this bacteria is the new world armadillos and African primates. At the beginning the idea that the habitat of this bacteria was in soil was just an hypothesis but some research were done and DNA of the m.leeprae was found in soil close to where peope were infected with leprosy. Its ideal temperature is about 30-33 degrees C

Pathology

M.leprae is responsible for the disease leprosy, a chronic disease that infects the peripheral nerves, the skin, the nervous system and the mucous membranes of the nose , throat and eyes. It has a slow growth rate and also a long incubation time. The symptoms of leprosy are skin lesions, pain and weakness. If left untreated it can cause nerve damage that can lead to numbness, deformities of extremeties.It can also cause blindness. It can be treated with multiple drug therapy but some strands are becaming resistant to some of the drugs. Transmission of the disease is not fully understood, and current research are being done on that. But scientists believe that it might be transmitted from infected individuals to uninfected ones through close contacts.

Current Research

Recent research are being done on strains of rifampin-resistant. In this reseaserch samples were taking from patients with reocurring leprosy. A punctual mutation was found in nucleotide 1367 of the rpoBgene. That mutation show strains of rifampin-resistant M.leprae in two of the three patients that were tested. This study took place in Agua de Dios in Colombia. Another research is being done on the mechanism of transmission of leprosy. This research was done in India. Another one is done to study M.leprae in leprosy patient in Malawi and India. In this research the scientist used short tandem repeat sequence to help them undrestand M.leprae.

References

1.[ "The discovery of the leprosy bacillus". Tidsskr Nor Laegeforen 122 (7): 708-9. PMID 11998735]

3.[Hernández E, Cardona-Castro N, Rodríguez G, Villegas S, Beltrán C, Kimura M, Vissa VD, Gómez Y. "Study of rifampin and dapsone resistance in three patients with recurring leprosy".Rev Panam Salud Publica. 2008 Feb;23(2):73-7.]

4.[http://microbewiki.kenyon.edu/index.php/Mycobacterium_leprae