Corynebacterium
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| Lehmann & Neumann 1896 |
Corynebacterium (from the Greek coryne = 'club') is a genus of aerobic to facultative anaerobic , gram-positive bacteria with a high GC content . The representatives are between 3 and 5 μm long, do not form spores and are immobile. Corynebacteria belong to the CMNR group, as do Mycobacterium, Nocardia and Rhodococcus. This group is characterized by a high G + C content in the genome, as well as mycolic acids , arabinogalactan and peptidoglycan in their cell membrane.
The genus is diverse; some representatives are pathogenic to humans or animals . Others are saprophytes and live on decaying plant remains. Some species are common in the mucosal flora and on human skin.
Features and evidence
A special feature of the cell wall, which serves as a characteristic for the Corynebacterium , are the meso- 2,6-diaminopimelic acids , the sugars galactose and arabinose and the mycolic acids contained in it. In the cell plasma, there are stainable granules, so-called polar granules, which contain polyphosphates . They are detected by the Neisser stain . The bacterium then appears yellow in color with dark polar grains at the end of the cell. The bacteria can be cultivated on blood agar , which contains the enzyme catalase, which is important for the identification of infectious diseases . A distinction between the different types can be made by detecting different metabolic reactions. The presence of the enzyme urease to break down urea, cystine breakdown , nitrate reduction, glucose fermentation and sucrose serve as criteria.
Cell shape and division
The cells of the Corynebacteria usually have a characteristic club shape. The shape is created by a swollen end of the cell. This cell morphology gave its name (koryne is ancient Greek and means "club"). Bacteria whose cells are thickened like a club at one end are generally referred to as " coryneforms ". Corynebacterium is pleomorphic , and during growth the shape can change between rod-shaped and cocoid .
Often cells stay connected after division, they appear in a V-shape under the microscope. This is caused by the so-called postfisionary snap movement (English: Snapping Postfission Movements), or simply snap division (Snapping Division). In Corynebacteria, the cell wall consists of two layers, only the inner one takes part in cell division, the outer one then surrounds the two daughter cells. Shortly after the division, the outer one tears in a limited place. The two cells then move from the side on which the rupture took place, they snap apart and now form the distinctive V-shape.
Pathogenicity
Pathogenic representatives of the corynebacteria , such as Corynebacterium diphtheriae, can cause diphtheria if they are infected by a certain bacteriophage . The so-called tox gene is transferred from corynebacteriophages to potentially pathogenic representatives and integrated into their genome. The tox gene codes for diphtheria toxin , which inhibits protein synthesis in the cytoplasm of the eukaryotic host cell and thus kills the human cell. If the bacterium is not infected by this bacteriophage, no classic diphtheria disease can occur. Some strains of the closely related Corynebacterium ulcerans are also able to trigger symptoms of diphtheria.
An important non-pathogenic Corynebacterium strain is Corynebacterium glutamicum , which is used as a model organism for the investigation of other pathogenic representatives. For the industry it is u. a. important as a producer of glutamic acid .
The usually multi - resistant gram-positive rod Corynebacterium jeikeium is a skin germ and mucous membrane colonist in humans. It can cause hospital-acquired wound infections, bacteremia, and endocarditis. Infections with it can be associated with foreign materials such as artificial shunts and prostheses. The antibiotic therapy takes place with vancomycin or rifampicin , alternatively also with teicoplanin or aminoglycosides .
Taxonomy
The corynebacteria belong to the actinobacteria, a group of gram-positive bacteria.
Some types:
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Corynebacterium afermentans (Riegel et al. 1993)
- Corynebacterium afermentans subsp. afermentans Riegel et al. 1993
- Corynebacterium afermentans subsp. lipophilum Riegel et al. 1993
- Corynebacterium ammoniagenes (Cooke and Keith 1927) Collins 1987 (Synonym: Brevibacterium ammoniagenes )
- Corynebacterium amycolatum (Collins et al. 1988)
- Corynebacterium atypicum (Hall et al. 2003)
- Corynebacterium auris (Funke et al. 1995)
- Corynebacterium bovis (Bergey et al. 1923)
- Corynebacterium callunae (Lee and Good 1963) Yamada and Komagata 1972
- Corynebacterium casei (Brennan et al. 2001)
- Corynebacterium confusum (Funke et al. 1998)
- Corynebacterium diphtheriae (Kruse 1886) Lehmann and Neumann 1896
- Corynebacterium equi (Magnusson 1923)
- Corynebacterium glucuronolyticum (Funke et al. 1995)
- Corynebacterium glutamicum (Kinoshita et al. 1958) Abe et al. 1967
- Corynebacterium halotolerans (Chen et al. 2004)
- Corynebacterium hansenii (Renaud et al. 2007)
- Corynebacterium jeikeium (Jackman et al. 1988)
- Corynebacterium minutissimum (ex Sarkany et al. 1962) Collins and Jones 1983 (trigger of erythrasma )
- Corynebacterium mycetoides (ex Castellani 1942) Collins 1983
- Corynebacterium pseudotuberculosis (Buchanan 1911, Eberson 1918)
- Corynebacterium resistens (Otsuka et al. 2005)
- Corynebacterium striatum (Chester 1901) Eberson 1918
- Corynebacterium tuscaniense (Riegel et al. 2006)
- Corynebacterium ulcerans (ex Gilbert and Stewart 1927) Riegel et al. 1995
- Corynebacterium urealyticum (Pitcher et al. 1992) (Corynebacteria of group D2)
- Corynebacterium uropygiale Markus Santhosh Braun, Stefan Zimmermann, Maria Danner, Harun-or Rashid & Michael Wink 2016
- Corynebacterium xerosis (Lehmann & Neumann 1896) Lehmann & Neumann 1899
Reporting requirement
In Germany, the direct or indirect detection of toxin-forming Corynebacteria is notifiable by name in accordance with Section 7 of the Infection Protection Act , if the evidence indicates an acute infection.
In Switzerland, a positive laboratory analysis result (or a negative result in a test for the toxin gene) for the pathogen Corynebacterium diphtheriae and other toxin-producing corynebacteria (C. ulcerans, C. pseudo-tuberculosis) must be reported in accordance with the Epidemics Act (EpG) with the Epidemic Ordinance and Annex 3 of the Ordinance of the FDHA on the reporting of observations of communicable diseases in humans .
literature
- Werner Köhler (Ed.) Medical Microbiology. 8th edition. Munich / Jena 2001, ISBN 978-3-437-41640-8 .
- Michael T. Madigan, John M. Martinko, Jack Parker: Brock - Microbiology. 11th edition. Pearson Studium, Munich 2006, ISBN 3-8274-0566-1 .
Web links
Individual evidence
- ↑ Wagner et al., 2010; Diphtheria in the United Kingdom, 1986-2008: the increasing role of Corynebacterium ulcerans. Epidemiol Infect. ; 138: 1519-30
- ^ Marianne Abele-Horn: Antimicrobial Therapy. Decision support for the treatment and prophylaxis of infectious diseases. With the collaboration of Werner Heinz, Hartwig Klinker, Johann Schurz and August Stich, 2nd, revised and expanded edition. Peter Wiehl, Marburg 2009, ISBN 978-3-927219-14-4 , p. 262.
- ↑ In: List of Prokaryotic names with Standing in Nomenclature (LPSN). Retrieved April 27, 2019 .