Mycobacterium bovis

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Mycobacterium bovis
Mycobacterium bovis BCG ZN.jpg

Mycobacterium bovis

Systematics
Department : Actinobacteria
Order : Actinomycetales
Subordination : Corynebacterineae
Family : Mycobacteriaceae
Genre : Mycobacterium
Type : Mycobacterium bovis
Scientific name
Mycobacterium bovis
Karlson & Lessel 1970

Mycobacterium bovis is a bacterium foundin cattle and causes tuberculosis in cattle . Mycobacterium bovis can also betransmitted tohumans and other domestic animals ( goats ). Infection in humans occurs primarily through unpasteurized milk ( raw milk ), but is now very rare in industrialized countries.

Mycobacterium bovis is part of the Mycobacterium tuberculosis complex, from which it probably originated several tens of thousands of years ago.

Through years of repeated cultivation of M. bovis which was live vaccine BCG (Bacillus Calmette-Guérin) provided a vaccine against by M. tuberculosis induced TB in humans.

The genome has been completely sequenced.

features

Like all species and strains of Mycobacteriaceae, Mycobacterium bovis is Gram-positive . The immobile cells are rod-shaped and do not form spores . The bacterium is acid-resistant, a typical feature of mycobacteria. Another important feature of all mycobacteria is the structure of the cell wall (including a high lipid content and content of waxy substances such as mycolic acids ). The resistance to various antibiotics and acid resistance are due to the special cell wall structure . Acid-fast bacteria do not release the dyes after coloring, despite acid treatment. An initial identification can be made using the Ziehl-Neelsen staining . After staining, the bacteria are treated with acid, only the acid-fast bacteria remain stained. However, other distantly related bacteria such as species of Nocardia , Rhodococcus and Corynebacterium are also acid-resistant .

All mycobacteria show a chemoorganotrophic metabolism and require oxygen (however, M. bovis cultures also survive short microaerobic periods).

Mycobacterium bovis is an obligate pathogen and, like Mycobacterium tuberculosis, is unable to reproduce outside the host. However, the mycobacteria are very well protected against external influences by the special cell wall and can also survive outside the host for a while. In the droppings of cattle, they should still be able to grow after up to 13 days.

Differences from other mycobacteria

The polymerase chain reaction (PCR) is a common method to differentiate Mycobacterium bovis from other mycobacteria. Furthermore, the different strains have morphological (visible in the cultures) and biochemical differences. Cultures of Mycobacterium bovis show a smooth, moist, glittering appearance and the addition of glycerine has a growth-inhibiting effect. Two differentiation features to M. tuberculosis cultures whose growth would be promoted by glycerol and which appear crumbly and dry on nutrient media. Mycobacterium tuberculosis is capable of producing niacin in the course of nitrate reduction , M. bovis is not.

Immediately after cultivation , Mycobacterium bovis behaves microaerophilically , it grows best in environments with low oxygen levels. After repeated cultivation, the strains require a normal (21%) oxygen content for growth and are then, like all other mycobacteria, obligatorily aerobic . This is another difference to Mycobacterium tuberculosis , which only shows the best growth when the oxygen content is full.

Bovine tuberculosis

Tubercular pleura of a cow.

In cattle, Mycobacterium bovis is usually transmitted via the air ( droplet infection ). The bacteria can also be ingested with infected food, milk or water.

Mycobacterium bovis can be transmitted to other animals such as cats, dogs, sheep, pigs, and goats. Bovine tuberculosis can also occur in the zoos, M. bovis was for. B. isolated from leopards, sea lions and baboons.

In Germany, measures to control bovine tuberculosis were carried out in the 1950s, which almost completely eradicated this disease. In 1952, 38.5% of the cattle examined were infected, in 1967 only 0.09%. After the eradication of bovine tuberculosis in the industrialized countries, cattle themselves are no longer the main source of infection. Rather, infection of cattle from domestic animals (e.g. cats) or even wild animals is the main risk for the outbreak of bovine tuberculosis. People suffering from open tuberculosis are also a source of infection for cattle (but not only through M. bovis ).

New Zealand

The disease was first discovered in mid-July 2017 on a dairy farm on New Zealand's South Island , and it has now spread to the North Island. The pathogens can lead to treatment-resistant mastitis , fertility disorders and miscarriages in cows or cause lung diseases and joint inflammation in cattle in general . The Ministry of Agriculture decided at the end of March 2018 that all cattle on infected farms must be culled. 22 holdings with a total of around 22,300 cattle were affected. By December 2017, 3,500 animals had already been killed. In May 2018 there was talk of another 150,000 planned culls .

Importance to humans

Bovine tuberculosis, called "bovine TB" in English, can also be transmitted to humans and is therefore one of the zoonoses . Infection occurs (as in cattle) via the respiratory tract or through ingestion, often through unpasteurized milk. The latter can trigger intestinal tuberculosis . Bovine tuberculosis can be transmitted back and forth between humans and cattle.

However, with the introduction of pasteurization of milk, the number of transmissions to humans fell sharply. Tuberculosis caused by Mycobacterium bovis hardly plays a role in the industrialized countries, but it is still important in the developing countries . In an Argentine study, two percent of the 448 cases of pulmonary tuberculosis examined could be traced back to an infection with M. bovis . The bacterial strains detected there were also those that most frequently infect cattle. A Chinese study found a 0.34 percent prevalence of M. bovis disease cases.

The changes in the affected organs from tuberculosis caused by Mycobacterium bovis are indistinguishable from the M. tuberculosis tuberculosis lesions.

Systematics

Within the genus Mycobacterium , Mycobacterium bovis and M. bovis BCG are assigned to the " Mycobacterium tuberculosis complex".

The two subspecies (subspecies) Mycobacterium bovis subsp. bovis and Mycobacterium bovis subsp. caprae are no longer available. The latter is now assigned to the species Mycobacterium caprae .

Synonyms for Mycobacterium bovis are Mycobacterium tuberculosis typus bovinus Lehmann & Neumann 1907 and Mycobacterium tuberculosis var. Bovis Bergey et al. 1934.

Reporting requirement

In Germany, the direct detection of Mycobacterium bovis in humans must be reported by name in accordance with Section 7 of the Infection Protection Act . The reporting obligation only applies if the direct evidence indicates an acute infection and, subsequently, for the result of the resistance determination; in advance also for the detection of acid-fast rods in the sputum.

In Switzerland, positive and negative laboratory-analytical findings of pathogens from the Mycobacterium tuberculosis complex in humans must be reported in accordance with the Epidemics Act (EpG) in conjunction with the Epidemics Ordinance and Annex 3 of the Ordinance of the FDHA on the reporting of observations of communicable diseases in humans .

literature

  • Martin Dworkin, Stanley Falkow, Eugene Rosenberg, Karl-Heinz Schleifer, Erko Stackebrandt (Eds.): The Prokaryotes, A Handbook of the Biology of Bacteria. 7 volumes, 3rd edition. Springer, New York et al. O., 2006, ISBN 0-387-30740-0 . Volume 3: Archaea. Bacteria: Firmicutes, actinomycetes. ISBN 0-387-25493-5 .
  • John G. Holt (Ed.): Bergey's manual of systematic bacteriology. Volume 2, 1986, ISBN 0-683-07893-3 .
  • Werner Köhler (Ed.) Medical Microbiology. 8th edition. Munich / Jena 2001, ISBN 978-3-437-41640-8 .
  • Michael Rolle, Anton Mayr (ed.): Medical microbiology, infection and epidemic theory. 7th edition. Enke, Stuttgart 1993, ISBN 3-432-84686-X .

Web links

Commons : Mycobacterium bovis  - collection of images, videos and audio files

Tuberculosis - Mycobacterium bovis (English)

Individual evidence

  1. ↑ SI Cadmus, HK Adesokan u. a .: Mycobacterium bovis and M. tuberculosis in goats, Nigeria. In: Emerging Infect. Dis. Volume 15, No. 12, December 2009, pp. 2066-2067, ISSN  1080-6059 . PMID 19961707 . PMC 3044523 (free full text).
  2. ↑ a b c Michael Rolle, Anton Mayr (ed.): Medical microbiology, infection and epidemic theory. 7th edition. Enke Verlag, Stuttgart 1993, ISBN 3-432-84686-X .
  3. ^ MF Thorel, C. Karoui, A. Varnerot, C. Fleury and V. Vincent: Isolation of Mycobacterium bovis from baboons, leopards and a sea-lion. In: Veterinary research , Vol. 29, Number 2, March-April, 1998: pp. 207-12. PMID 9601152
  4. ↑ N: 22,300 cattle are culled In: schweizerbauer.ch , April 2, 2018, accessed on April 2, 2018.
  5. ↑ NZ: 3,500 cattle already culled In: schweizerbauer.ch , December 19, 2017, accessed on April 2, 2018.
  6. ↑ Cattle disease in New Zealand: 150,000 cows have to die - to kill a bacterium In: srf.ch , May 28, 2018, accessed on May 29, 2018.
  7. ^ Sophia Wagner: Cattle epidemic in New Zealand - 150,000 animals are to be culled. In: deutschlandfunk.de. June 13, 2018. Retrieved August 29, 2018 .
  8. ↑ apa: New Zealand has to slaughter more than 150,000 cattle because of the disease. In: derstandard.at . May 28, 2018. Retrieved August 29, 2018 .
  9. ↑ Geoff Brumfiel: Badger battle erupts in England. Cull plan splits farmers, conservationists - and scientists. In: Nature . Volume 490, 2012, pp. 317-318, doi: 10.1038 / 490317a
  10. ↑ Etchechoury I, Valencia GE, Morcillo N, et al. : Molecular typing of Mycobacterium bovis isolates in Argentina: first description of a person-to-person transmission case . In: Zoonoses and Public Health . 57, No. 6, September 2010, pp. 375-81. doi : 10.1111 / j.1863-2378.2009.01233.x . PMID 19912616 .
  11. ^ Y. Chen, Y. Chao et al .: Potential challenges to the Stop TB Plan for humans in China; cattle maintain M. bovis and M. tuberculosis. In: Tuberculosis (Edinb). Volume 89, Number 1, January 2009, pp. 95-100, ISSN  1873-281X . doi : 10.1016 / j.tube.2008.07.003 . PMID 19056318 .
  12. ^ A b Jean Euzéby, Aidan C. Parte: Genus Mycobacterium. In: List of Prokaryotic names with Standing in Nomenclature ( LPSN ). Retrieved December 23, 2013 .
  13. ↑ tuberculosis. RKI advisor. In: rki.de. Robert Koch Institute, February 21, 2013, accessed on March 18, 2020 (reporting obligation according to IfSG).