Mycobacterium avium
Mycobacterium avium | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Mycobacterium avium |
||||||||||||
Systematics | ||||||||||||
|
||||||||||||
Scientific name | ||||||||||||
Mycobacterium avium | ||||||||||||
Chester , 1901 |
Mycobacterium avium is a slowly growing species of bacteria, the three known subspecies (subspecies) of which are all pathogens.
The nominate form Mycobacterium avium ssp. avium is the causative agent of avian tuberculosis , Mycobacterium avium ssp. paratuberculosis is the causative agent of paratuberculosis in cattle and may also be involved in the development of Crohn's disease in humans. Mycobacterium avium ssp. silvaticum also causes tuberculosis in birds and paratuberculosis in mammals.
features
Mycobacterium avium is rod-shaped and the surface of cultures is smooth or rough. Most of the known strains are non-photochromogenic, a few are scotochromogenic and turn light yellow in color. Temperatures around 37 ° C are required for their growth.
Systematics
Mycobacterium avium belongs to the so-called MAIS-complex within the genus ( M ycobacterium a Vium i ntracellulare s crofulaceum ), the species can be due to many common features distinguished only by genetic analysis (16S rRNA) of one another. Pathogenicity and the host range are considered to be important characteristics .
Pathogenicity
Mycobacterium avium occupies a special position because on the one hand it causes avian tuberculosis, on the other hand it also occurs as a pathogen in humans and mammals. Chickens are most receptive , followed by pigeons , birds of prey and waterfowl. It can also be found in small birds / pets. The pathogen is also absorbed through the food chain, e.g. B. from rats . Infections in humans or mammals are called mycobacterioses . They are most likely to occur in cattle and pigs and may have an effect. a. as a causative agent of mastitis in cows. The pathogen belongs to the non-tuberculous mycobacteria , can be found in tap water, is heat-resistant up to 140 ° C (i.e. cannot be eliminated by boiling) and can cause dangerous pneumonia with tuberculosis-like symptoms in people with a weakened immune system. The pathogen is particularly dangerous because it is often not recognized in time and conventional broad-spectrum antibiotics are not effective. Azithromycin is given as prophylaxis . A combination therapy consisting of isoniazid and high-dose cefpodoxime proved to be effective .
Due to the relatively time-consuming cultivation of Mycobacterium avium ssp. paratuberculosis or long incubation phases, there is often a delayed detection of paratuberculosis infection in ruminant populations. For this reason it is now being investigated ( in vitro and in vivo ) whether indications of paratuberculosis infections can be supported by the detection of specific changes in the concentration of volatile organic compounds (VOCs).
literature
- Marie-Francoise Thorel, Micah Krichevsky, Veronique Vincent Levy-Frebault: Numerical Taxonomy of Mycobactin-Dependent Mycobacteria, Emended 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. In: International Journal of Systematic and Evolutionary Microbiology. 1990, 40, pp. 254-260.
- Sybe Hartmans, Jan AM De Bont, Erko Stackebrandt: The Genus Mycobacterium — Nonmedical. In: The Prokaryotes. 2006; 3, pp. 889-918, doi : 10.1007 / 0-387-30743-5_33
Web links
Individual evidence
- ^ Phillip Trefz, Heike Koehler, Klaus Klepik, Petra Moebius, Petra Reinhold: Volatile Emissions from Mycobacterium avium subsp. paratuberculosis Mirror Bacterial Growth and Enable Distinction of Different Strains . In: PLOS ONE . tape 8 , no. 10 , October 8, 2013, ISSN 1932-6203 , p. e76868 , doi : 10.1371 / journal.pone.0076868 , PMID 24116177 ( plos.org [accessed June 11, 2017]).
- ↑ Andreas Bergmann, Phillip Trefz, Sina Fischer, Klaus Klepik, Gudrun Walter: In Vivo Volatile Organic Compound Signatures of Mycobacterium avium subsp. paratuberculosis . In: PLOS ONE . tape 10 , no. 4 , April 27, 2015, ISSN 1932-6203 , p. e0123980 , doi : 10.1371 / journal.pone.0123980 , PMID 25915653 ( plos.org [accessed June 11, 2017]).