Mycobacterium leprae
Microphotograph of Mycobacterium leprae taken from a skin lesion. Source: CDC
Scientific classification
Kingdom: Bacteria Phylum: Actinobacteria Order: Actinomycetales Suborder: Corynebacterineae Family: Mycobacteriaceae Genus: Mycobacterium Species: M. leprae
Binomial name
Mycobacterium leprae Hansen, 1874

Mycobacterium leprae, also known as Hansen’s bacillus, is the bacterium that causes leprosy (Hansen's disease). It is an intracellular, pleomorphic, acid fast bacterium. M. leprae is a gram-positive aerobic rod-shaped (bacillus) surrounded by the characteristic waxy coating unique to mycobacteria. In size and shape, it closely resembles Mycobacterium tuberculosis. Due to its thick waxy coating, M. leprae stains with a carbol fuscin rather than with the traditional Gram stain. The culture takes several weeks to mature. Image File history File links Mycobacterium_leprae. ... Scientific classification or biological classification is a method by which biologists group and categorize species of organisms. ... Phyla/Divisions Actinobacteria Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Nitrospirae Omnibacteria Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Bacteria (singular, bacterium) are a major group of living organisms. ... Subclasses Acidimicrobidae Actinobacteridae Coriobacteridae Rubrobacteridae Sphaerobacteridae The Actinobacteria or Actinomycetes are a group of Gram-positive bacteria. ... Suborders Actinomycineae Corynebacterineae Frankineae Glycomycineae Micrococcineae Micromonosporineae Propionibacterineae Pseudonocardineae Streptomycineae Streptosporangineae Actinomycetales is an order of Actinobacteria. ... Families Corynebacteriaceae (Coryneform bacteria) Dietziaceae Gordoniaceae Mycobacteriaceae Nocardiaceae Tsukamurellaceae Williamsiaceae Corynebacterineae is a suborder of Actinomycetales. ... Species See text. ... Species See text. ... In biology, binomial nomenclature is the formal method of naming species. ... Gerhard Henrick Armauer Hansen (July 29, 1841 - February 12, 1912) was a Norwegian physician, remembered for his identification of Mycobacterium leprae as the causative agent of leprosy in 1873. ... Phyla/Divisions Actinobacteria Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Nitrospirae Omnibacteria Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Bacteria (singular, bacterium) are a major group of living organisms. ... This article or section is in need of attention from an expert on the subject. ... A bacillus is a rod-shaped bacterium: an acid-fast bacillus (or AFB) is a rod-shaped bacterium which, when stained with certain compounds, retains that stain despite treatment with an acidic solution. ... Look up Aerobic in Wiktionary, the free dictionary. ... Species see text Mycobacterium is the a genus of actinobacteria, given its own family, the Mycobacteriaceae. ... Binomial name Mycobacterium tuberculosis Zopf 1883 Mycobacterium tuberculosis is the bacterium that causes most cases of tuberculosis[1]. It was first described on March 24, 1882 by Robert Koch, who subsequently received the Nobel Prize in physiology or medicine for this discovery in 1905. ... Gram staining is a method for staining samples of bacteria that differentiates between the two main types of bacterial cell wall. ...

Optical microscopy shows M. leprae in clumps, rounded masses, or in groups of bacilli side by side.

It was discovered in 1873 by the Norwegian physician Gerhard Armauer Hansen, who was searching for the bacteria in the skin nodules of patients with leprosy. It was the first bacterium to be identified as causing disease in man. ^[1] 1873 (MDCCCLXXIII) was a common year starting on Wednesday (see link for calendar). ... Gerhard Henrick Armauer Hansen (July 29, 1841 - February 12, 1912) was a Norwegian physician, remembered for his identification of Mycobacterium leprae as the causative agent of leprosy in 1873. ...

The organism has never been successfully grown on an artificial cell culture media. Instead it has been grown in mouse foot pads and more recently in nine-banded armadillos. This can be used as a diagnostic test for the presence of bacillus in body lesions of suspected leprosy patients. The bacterium can infect armadillos, so it is studied in them (see Animal Rights). The difficulty in culturing the organism appears to be due to the fact that the organism is an obligate intra-cellular parasite that lacks many necessary genes for independent survival. The complex and unique cell wall that makes members of the Mycobacterium genus difficult to destroy is apparently also the reason for the extremely slow replication rate. Families Pampatheriidae (prehistoric) Glyptodontidae (prehistoric) Dasypodidae Armadillos are small placental mammals, known for having a bony armor shell. ... Families Pampatheriidae (prehistoric) Glyptodontidae (prehistoric) Dasypodidae Armadillos are small placental mammals, known for having a bony armor shell. ... A civet, or sea fox, photographed in the Zigong Peoples Zoo, Sichuan, 2001. ... A parasite is an organism that spends a significant portion of its life in or on the living tissue of a host organism and which causes harm to the host without immediately killing it. ... Species See text. ...

Virulence factors include a waxy exterior coating, formed by the production of mycolic acids unique to Mycobacterium. Species See text. ...

M. leprae is sensitive to dapsone (diaminodiphenylsulfone, the first effective treatment which was discovered for leprosy in the 1940's), but resistance against this antibiotic has developed over time. Therapy with dapsone alone is now strongly contraindicated. Currently, a multidrug treatment (MDT) is recommended by the World Health Organization, including dapsone, rifampicin and clofazimine. In patients receiving the MDT, a high proportion of the bacilli die within a short amount of time without immediate relief of symptoms. This suggests that many symptoms of leprosy must be due in part to the presence of dead cells. Dapsone is an antibiotic medication most commonly used for the treatment of Mycobacterium leprae infections (leprosy). ... Antibiotic resistance is the ability of a micro-organism to withstand the effects of an antibiotic. ... Staphylococcus aureus - Antibiotics test plate. ... The World Health Organization (WHO) is a specialized agency of the United Nations that acts as a coordinating authority on international public health, headquartered in Geneva, Switzerland. ... Dapsone is an antibiotic medication most commonly used for the treatment of Mycobacterium leprae infections (leprosy). ... Rifampicin (INN) (IPA: ) or rifampin (USAN) is a bacteriocidal antibiotic drug of the rifamycin group. ... Clofazimine is a fat-soluble riminophenazine dye used for the treatment of leprosy. ... Orders Bacillales Lactobacillales The term bacilli (singular bacillus) is used to refer to any rod-shaped bacteria. ...

External links

• The genome of Mycobacterium leprae
• "Mycobacterium leprae" Quick Reference

References

1. ^ Hansen G. A. Norsk Magazin for Laegevidenskaben. 1874; 4: 76.