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Encyclopedia > Mycobacterium tuberculosis
Mycobacterium tuberculosis
M. tuberculosis bacterial colonies
M. tuberculosis bacterial colonies
Scientific classification
Kingdom: Bacteria
Phylum: Actinobacteria
Order: Actinomycetales
Suborder: Corynebacterineae
Family: Mycobacteriaceae
Genus: Mycobacterium
Species: M. tuberculosis
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; the bacterium is also known as Koch's bacillus. The M. tuberculosis genome was sequenced in 1998.[2][3] This is a close-up of a Mycobacterium tuberculosis culture revealing this organism’s colonial morphology. ... For other uses, see Scientific classification (disambiguation). ... 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. ... This article does not cite any references or sources. ... 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. ... Tuberculosis (abbreviated as TB for tubercle bacillus or TuBerculosis) is a common and deadly infectious disease caused by mycobacteria, mainly Mycobacterium tuberculosis. ... is the 83rd day of the year (84th in leap years) in the Gregorian calendar. ... Year 1882 (MDCCCLXXXII) was a common year starting on Sunday (link will display the full calendar) of the Gregorian calendar (or a common year starting on Friday of the 12-day slower Julian calendar). ... For the American lobbyist, see Bobby Koch. ... List of Nobel Prize laureates in Physiology or Medicine from 1901 to the present day. ... In biology the genome of an organism is the whole hereditary information of an organism that is encoded in the DNA (or, for some viruses, RNA). ... For the sense of sequencing used in electronic music, see the music sequencer article. ... Year 1998 (MCMXCVIII) was a common year starting on Thursday (link will display full 1998 Gregorian calendar). ...

Contents

Physiology

M. tuberculosis is an obligate aerobe ( weakly Gram-positive mycobacterium, hence Z.N. staining is used). While mycobacteria do not seem to fit the Gram-positive category from an empirical standpoint (i.e. they do not retain the crystal violet stain), they are classified as an acid-fast Gram positive bacterium due to their lack of an outer cell membrane.[1] M. tuberculosis divides every 15 to 20 hours—extremely slowly compared to other bacteria, which tend to have division times measured in minutes (for example, E. coli can divide roughly every 20 minutes). It is a small, rod-like bacillus that can withstand weak disinfectants and can survive in a dry state for weeks. An aerobic organism or aerobe is an organism that has an oxygen based metabolism. ... 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. ... Species Bacillus anthracis Bacillus cereus Bacillus coagulans Bacillus globigii Bacillus licheniformis Bacillus natto Bacillus subtilis Bacillus sphaericus Bacillus thuringiensis etc. ... This is an article about antimicrobial agents. ...


Diagnosis

Sputum is taken in 3 successive mornings as the number of organisms could be low, and the specimen is treated with 3% KOH or NaOH for liquefaction and decontamination. Gram stain should never be performed as the organism is an "acid-fast bacillus" (AFB), meaning that it retains certain stains after being treated with acidic solution. In the most common staining technique, the Ziehl-Neelsen stain, AFB are stained a bright red, which stands out clearly against a blue background; therefore, the bacteria are sometimes called red snappers.[4] The reason for the acid-fast staining is because of its thick waxy cell wall.[5] The waxy quality of the cell wall is mainly due to the presence of mycolic acids. This waxy cell wall also is responsible for the typical caseous granuloma formation in tuberculosis. The component responsible, trehalose dimycolate, is called the cord factor. A grading system exists for interpretation of the microscopic findings based on the number of organisms obsereved in each field. Acid-fast bacilli can also be visualized by fluorescent microscopy using auramine-rhodamine stain which makes them appear somewhat golden in color. Also, M. tuberculosis is grown on a selective medium known as Lowenstein-Jensen medium which have traditionally been used for this purpose. However, this method is quite slow; as this organism requires 6-8 months to grow which certainly delays reporting of results. A faster results can now be obtained using Middlebrook medium. The chemical compound potassium hydroxide, (KOH) sometimes known as caustic potash, potassa, potash lye, and potassium hydrate, is a metallic base. ... Sodium hydroxide (NaOH), also known as lye, caustic soda and sodium hydrate, is a caustic metallic base. ... Gram staining is a method for staining samples of bacteria that differentiates between the two main types of bacterial cell wall. ... 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. ... The Ziehl-Neelsen stain, also known as the acid-fast stain, was first described by two german doctors; Franz Ziehl (1859 to 1926), a bacteriologist and Friedrich Neelsen (1854 to 1894), a pathologist. ... Mycolic acid is an acid known for protecting the cell bodies of mycobacterium, which include tuberculosis. ... Necrosis (in Greek Νεκρός = Dead) is the name given to unprogrammed death of cells/living tissue (compare with apoptosis - programmed cell death). ... H&E section of non-caseasting granuloma seen in the colon of a patient with Crohns disease In medicine (anatomical pathology), a granuloma is a group of epithelioid macrophages surrounded by a lymphocyte cuff. ... The auramine-rhodamine stain is a histological technique used to see acid-fast bacilli, notably Mycobacteria. ...


See Also

Philip Montagu D’Arcy Hart, CBE, (June 25, 1900 - July 30, 2006) was a British medical researcher and pioneer in tuberculosis treatment. ...

References

  1. ^ a b Ryan KJ; Ray CG (editors) (2004). Sherris Medical Microbiology, 4th ed., McGraw Hill. ISBN 0-8385-8529-9. 
  2. ^ Cole ST; Brosch R; Parkhill J; et al. (1998). "Deciphering the biology of Mycobacterium tuberculosis from the complete genome sequence.". Nature 393: 537–544. 
  3. ^ Camus JC; Pryor MJ; Medigue C; Cole ST. (148). "Re-annotation of the genome sequence of Mycobacterium tuberculosis H37Rv". Microbiology 2002: 2967–2973. 
  4. ^ Flowers T (1995). "Quarantining the noncompliant TB patient: catching the "Red Snapper"". Journal of health and hospital law : a publication of the American Academy of Hospital Attorneys of the American Hospital Association 28 (2): == h == 95-105. PMID 10141473. 
  5. ^ Madigan, Michael; Martinko, John (editors) (2005). Brock Biology of Microorganisms, 11th ed., Prentice Hall. ISBN 0-13-144329-1. 

External links

  • Database of Mycobacterium tuberculosis genome sequences and related information.

 
 

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