Actinomyces
| Actinomyces | ||||||||||||
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Actinomyces israelii |
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| Scientific name | ||||||||||||
| Actinomyces | ||||||||||||
| Harz 1877 | ||||||||||||
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Actinomyces is a bacteria - genus of the family Actinomycetaceae . These bacteria are characterized by elongated, often branched cells , without active movement, predominantly anaerobic growth and positive behavior in the Gram stain .
Shape, cell structure
Usually straight or curved rod-shaped cells with a diameter of 0.2 to 3.0 µm. The length is very different, mostly the individuals are long filamentous - up to a length of 50 µm or even more. Some species form small, branched mycelia . The long-thread forms and mycelia occasionally multiply by breaking up into short cells (segmentation). Endospores are not formed. Grief behavior positive. No active movement.
metabolism
Actinomyces species are predominantly anaerobic, some are facultative aerobic , and only a few possess the enzyme catalase . In some species (CO is a high carbon dioxide 2 or bicarbonate (HCO -) 3 - ) concentration in the culture medium growth under aerobic enables conditions. Most species require a complex range of nutrients to grow. Often they have a fermentative energy metabolism in which carbohydrates are converted into organic acids .
Occurrence, way of life
Most species occur in warm-blooded vertebrates , either as pathogens or as commensals . The optimum temperature for growth is therefore relatively high: 30 to 37 ° C. Actinomyces bovis, for example, is often found in the mouth of cattle. The pathogenic species, especially A. israelii , cause various diseases ( actinomycoses ), especially abscesses in the oral cavity and gastrointestinal tract .
origin of the name
In the 19th century , tuberous concretions caused by Actinomyces species in various affected parts of the body of animals received particular attention . In the cross-section through these so-called " drusen " based on an expression of mineralogy , a radiating structure is shown, which is caused by the radiating growth of the bacterial hyphae starting from a point . Since at that time bacteria of the genus Actinomyces as well as other mycelium-forming bacteria (such as those of the genus Streptomyces ) were thought to be fungi , they were given the German name "Strahlpilze" like other Actinomycetaceae; In biology, the corresponding term was "actinomycetes" (or "actinomycetes"), formed from the ancient Greek ακτίς - aktis = ray and μύκης - mykes = mushroom. In 1877, the German botanist Carl Otto Harz named the causative agent of such a concretion in a cattle Actinomyces bovis .
literature
- Klaus P. Schaal, Atteyet F. Yassin, Erko Stackebrandt: The Family Actinomycetaceae: The Genera Actinomyces, Actinobaculum, Arcanobacterium, Varibaculum, and Mobiluncus . In: Martin Dworkin, Stanley Falkow, Eugene Rosenberg, Karl-Heinz Schleifer, Erko Stackebrandt (Eds.): The Prokaryotes - A Handbook on the Biology of Bacteria . 3rd edition, Vol. 3: Archaea. Bacteria: Firmicutes, Actinomycetes. Springer Verlag, New York 2006, pp. 430-537, ISBN 978-0-387-25493-7 (print), ISBN 978-0-387-30743-5 (online), doi : 10.1007 / 0-387-30743 -5_21 .
- Eija Könönen, William G. Wade: Actinomyces and Related Organisms in Human Infections. In: Clinical Microbiology Reviews, Volume 28, 2015, Issue 2, pages 419-442. doi : 10.1128 / CMR.00100-14
Web links
Individual evidence
- ↑ Hans von Kress (ed.): Müller - Seifert . Pocket book of medical-clinical diagnostics. 69th edition. Published by JF Bergmann, Munich 1966, p. 1062.