''Mycobacterium avium'' subspecies ''paratuberculosis''

Mycobacterium avium subspecies paratuberculosis (MAP) is an obligate pathogenic bacterium in the genus Mycobacterium.[1] It is often abbreviated M. paratuberculosis or M. avium ssp. paratuberculosis. It is the causative agent of Johne's disease, which affects ruminants such as cattle, and suspected causative agent in human Crohn's disease. The type strain is ATCC 19698 (equivalent to CIP 103963 or DSM 44133).[2]

Pathophysiology

MAP causes Johne's disease in cattle and other ruminants, and it has long been suspected as a causative agent in Crohn's disease in humans;[3][4]

Recent studies have shown that MAP present in milk can survive pasteurization, which has raised human health concerns due to the widespread nature of MAP in modern dairy herds. MAP survival during pasteurization is dependent on the D72C-value of the strains present and their concentration in milk. It is heat resistant and is capable of sequestering itself inside white blood cells, which may contribute to its persistence in milk. It has also been reported to survive chlorination in municipal water supplies.

MAP is a slow growing organism and is difficult to culture. Bacterial cultures were regarded as Gold standards for detection of MAP. Detection is very limited in fresh tissues, food, and water. Recently, John Aitken and Otakaro Pathways have discovered a method to culture MAP from human blood. Testing is ongoing. Professor John Hermon-Taylor of Kings College London is developing a new vector type anti MAP vaccine which he claims is both curative and preventative. Stage 1 human trials began in January 2017. He is also developing a companion MAP blood test.

It is not susceptible to antituberculosis drugs (which can generally kill Mycobacterium tuberculosis). MAP is susceptible to antibiotics used to treat Mycobacterium avium disease, such as rifabutin and clarithromycin, however the capacity of these antibiotics to eradicate MAP infection in vivo has not been established.

Crohn's disease

MAP is recognized as a multi-host mycobacterial pathogen with a proven specific ability to initiate and maintain systemic infection and chronic inflammation of the intestine of a range of histopathological types in many animal species, including primates.[5]

MAP has been found in larger numbers within the intestines of Crohn's disease patients[6] and in significant amount of irritable bowel syndrome patients[7] compared to those suffering from ulcerative colitis or otherwise healthy controls.

Genome

The genome of MAP strain K-10 was sequenced in 2005 and found to consist of a single circular chromosome of 4,829,781 base pairs, and to encode 4,350 predicted ORFs, 45 tRNAs, and one rRNA operon.[8]

See also

References

  1. ↑ Ryan KJ; Ray CG, eds. (2004). Sherris Medical Microbiology (4th ed.). McGraw Hill. ISBN 0-8385-8529-9.
  2. ↑ Thorel M, Krichevsky M, Lévy-Frébault V (1990). "Numerical taxonomy of mycobactin-dependent mycobacteria, amended description of Mycobacterium avium, and description of Mycobacterium avium subsp. avium subsp. nov., Mycobacterium avium subsp. paratuberculosis subsp. nov., and Mycobacterium avium subsp. silvaticum subsp. nov". Int J Syst Bacteriol. 40 (3): 254–60. PMID 2397193. doi:10.1099/00207713-40-3-254.
  3. ↑ Hermon-Taylor, J (2009). "Mycobacterium avium subspecies paratuberculosis, Crohn's disease and the Doomsday scenario". Gut Pathogens. 1 (15): 15. PMC 2718892 Freely accessible. PMID 19602288. doi:10.1186/1757-4749-1-15..
  4. ↑ Freeman H, Noble M (2005). "Lack of evidence for Mycobacterium avium subspecies paratuberculosis in Crohn's disease regulation of immunity". Inflammatory Bowel Diseases. 11 (8): 782–3. PMID 16043998. doi:10.1097/01.MIB.0000179317.27132.24.
  5. ↑ "Johne's Information Center". Retrieved 2008-06-13.
  6. ↑ Sanderson JD, Moss MT, Tizard ML, Hermon-Taylor J (1992). "Mycobacterium paratuberculosis DNA in Crohn's disease tissue". Gut. 33 (7): 890–6. PMC 1379400 Freely accessible. PMID 1644328. doi:10.1136/gut.33.7.890.
  7. ↑ Scanu, Antonio M.; Bull, Tim J.; Cannas, Sara; Sanderson, Jeremy D.; Sechi, Leonardo A.; Dettori, Giuseppe; Zanetti, Stefania; Hermon-Taylor, John (December 2007). "Mycobacterium avium Subspecies paratuberculosis Infection in Cases of Irritable Bowel Syndrome and Comparison with Crohn's Disease and Johne's Disease: Common Neural and Immune Pathogenicities". Journal of Clinical Microbiology. 45 (12): 3883–3890. ISSN 0095-1137. PMC 2168579 Freely accessible. PMID 17913930. doi:10.1128/JCM.01371-07. Mycobacterium avium subsp. paratuberculosis was detected in 15 of 20 (75%) patients with irritable bowel syndrome, 3 of 20 (15%) healthy controls, and 20 of 23 (87%) people with Crohn's disease
  8. ↑ Li L, Bannantine J, Zhang Q, Amonsin A, May B, Alt D, Banerji N, Kanjilal S, Kapur V (2005). "The complete genome sequence of Mycobacterium avium subspecies paratuberculosis". Proc Natl Acad Sci USA. 102 (35): 12344–9. PMC 1194940 Freely accessible. PMID 16116077. doi:10.1073/pnas.0505662102.
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