Mycoplasma

from Wikipedia, the free encyclopedia
Mycoplasma
Mycoplasma gallisepticum

Mycoplasma gallisepticum

Systematics
Domain : Bacteria (bacteria)
Department : Tenerife
Class : Mollicutes
Order : Mycoplasmatales
Family : Mycoplasmataceae
Genre : Mycoplasma
Scientific name
Mycoplasma
Nowak 1929

Mycoplasma , also known as mycoplasma in German(from ancient Greek μύκης mýkēs “mushroom” and πλάσμα plásma “the formed”) are a genus of very small bacteria from the class of Mollicutes (from Latin mollis “soft” and cutis “skin”, “the Soft-skinned "). In contrast to all other bacteria, they lack a cell wall . They live aerobically to facultatively anaerobically and are of diverse (pleomorphic), variable, vesicular shape.

Mycoplasmas are mostly parasitic , intra- and extracellular living bacteria that are the cause of numerous diseases in humans and vertebrates. Few species are commensal or opportunistic pathogens. The first species was isolated and described from sick cattle in 1898. The mushroom-like thread shapes often observed gave the genus Mycoplasma its name . In human medicine it was not until 1962 that the species Mycoplasma pneumoniae was assigned to a disease.

With a size of 580–1,380 kbp , the genera Mycoplasma and Ureaplasma have the smallest genome of the prokaryotes capable of auto- replication with the exception of the deep-sea archaeon Nanoarchaeum equitans (~ 500 kbp) and the leaf flea endosymbiont Carsonella ruddii (about 160 kbp) . Their genome usually has a relatively low guanine - cytosine (GC) content and their cell membrane contains cholesterol, which is otherwise only found in eukaryotes .

Classification

The genus Mycoplasma belongs to the family Mycoplasmataceae . This family is placed in the Mollicutes class within the Tenerife department.

A common characteristic of the class Mollicutes (soft skin) and thus also of the mycoplasma is the lack of a cell wall and the associated susceptibility to osmotic fluctuations in the surrounding medium. Antibiotics that attach to the cell wall (e.g. penicillins ) are practically ineffective against them. Due to the small size of the mycoplasma, unlike other bacteria, they cannot be retained by sterile filters with a nominal pore size of 0.22 µm. Molecular-phylogenetic rRNA investigations showed that the mollicutes are not at the base of the bacterial phylogenetic tree, but rather emerged through degenerative evolution from Gram-positive bacteria of the Lactobacillus group with a low GC content of the DNA . In the course of this degenerative evolution the Mollicutes have lost a considerable part of their genetic information, so that today they are among the living things with the smallest known genome (Mollicutes: 580–2,300 kbp, E. coli : 4,500 kbp, Arabidopsis thaliana : 100,000 kbp, Homo sapiens : 3,400,000 kbp). Bacteria of the class Mollicutes do not live as free bacteria, but are either dependent on a host cell or a host organism.

As parasites or commensals , they receive essential metabolic components from the host organism, such as B. fatty acids , amino acids and precursors of nucleic acids . The possibility of downsizing the genome is attributed to the parasitic way of life of the Mollicutes. For the growth of some representatives of the Mollicutes, cholesterol is also required, a component that is normally not found in bacteria and whose synthesis precursors are also provided by the host cells.

Clinically important mycoplasma

As parasitic bacteria, mycoplasmas are the cause of numerous diseases in humans and vertebrates. As a rule, however, bacteria from the class of the Mollicutes do not kill their host. Rather, they cause chronic infections, which speaks for a good adaptation to the hosts, and thus embody a very successful type of parasitism. Some species are also opportunistic pathogens, a few species have also been described as harmless commensals, for example the species Mycoplasma cottewii was found in the ear canals and, less frequently, in the paranasal sinuses of goats , pathogenicity could not be proven.

Human medicine

Veterinary medicine

Cell culture

In addition to their clinical importance, mycoplasmas (mainly mycoplasma oral ) are also the most dangerous contaminants in normal cell culture . Since they cannot be seen under a light microscope and they are resistant to standard antibiotics, they often go undetected and thus affect cellular growth and results.

Sampling, transport and evidence

Due to the lack of a bacterial cell wall , the mycoplasmas in samples and test materials are very sensitive to dehydration. Samples on swabs must therefore be processed quickly or placed in a transport medium. Mycoplasma in tissue and sputum samples can be transported untreated. An interval of 24 to 48 hours between sampling and sample analysis can be bridged with cooling to +4 ° C. It is also possible to freeze the samples to −70 ° C. Since mycoplasmas do not have a cell wall, they can only be grown on special culture media. The polymerase chain reaction (PCR) has therefore established itself as a fast and cheap standard method for detection. However, this does not apply to all mycoplasmas.

literature

  • 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. 219 f.
  • Martin Dworkin, Stanley Falkow, Eugene Rosenberg, Karl-Heinz Schleifer , Erko Stackebrandt (eds.): The Prokaryotes. A Handbook on the Biology of Bacteria. 3rd edition, Volume 4: Bacteria: Firmicutes, Cyanobacteria . Springer, New York, NY 2006, ISBN 978-0-387-25494-4 (English: print edition), ISBN 978-0-387-30744-2 (online edition), doi : 10.1007 / 0-387- 30744-3 .
  • Otto Gsell, U. Krech, Werner Mohr (Ed.): Clinical virology. Including chlamydia, coxiae and mycoplasma . Advances in diagnostics, therapy and prophylaxis. Urban and Fischer, Munich 1991, ISBN 3-541-12201-3 .
  • Irmgard Gylstorff, JM Bové: Infections through Mycoplasmatales , Enke, Stuttgart 1985, ISBN 3-432-94881-6 (licensed edition by Gustav Fischer Verlag Jena).
  • Shmuel Razin, Joseph G. Tully (Eds.): Molecular and Diagnostic Procedures in Mycoplasmology. Vol. 1: Molecular Characterization. Academic Press, San Diego, CA / London 1995. ISBN 0-12-583805-0 (English).

Remarks

  1. ↑ a b c d Henning (Ed.) Brandis and colleagues. by R. Ansorg Brandis: Textbook of medical microbiology: 192 tables , 7th, completely revised. Edition, G. Fischer, Stuttgart [u. a.] 1994, ISBN 3437007432 , pp. 66, 172, 610ff.
  2. ↑ Systematics according to JP Euzéby: List of Prokaryotic Names with Standing in Nomenclature - as of September 15, 2018
  3. ↑ George M. Garrity : Bergey's Manual of Systematic Bacteriology . Volume 5: The Bacteroidetes, Spirochaetes, Tenericutes (Mollicutes), Acidobacteria, Fibrobacteres, Fusobacteria, Dictyoglomi, Gemmatimonadetes, Lentisphaerae, Verrucomicrobia, Chlamydiae, and Planctomycetes . Springer, New York 2011, ISBN 978-0-387-95042-6 .
  4. ^ Daniel G. Gibson et al .: Complete Chemical Synthesis, Assembly, and Cloning of a Mycoplasma genitalium Genome. In: Science . Volume 319, No. 5867, 2008, pp. 1215–1220, doi: 10.1126 / science.1151721
    netzeitung.de ( memento from January 6, 2010 in the Internet Archive ): Venter presents artificial bacterial genome.
  5. ^ 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. 219 f.
  6. ↑ E.g. beef tripticase soy broth with 0.5% beef albumin and penicillin G)

Web links

Commons : Mycoplasma ( Mycoplasma )  - Collection of images, videos and audio files