Streptococci

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Streptococci
Streptococcus pneumoniae secondary electron micrograph, colored

Streptococcus pneumoniae
secondary electron micrograph, colored

Systematics
Domain : Bacteria (bacteria)
Department : Firmicutes
Class : Bacilli
Order : Lactic acid bacteria (Lactobacillales)
Family : Streptococcaceae
Genre : Streptococci
Scientific name
Streptococcus
Rosenbach 1884

Streptococci (German plural from the Latin singular Streptococcus , which is made up of the two ancient Greek components στρεπτός streptós 'necklace', 'twisted', 'chain-shaped', and κόκκος kókkos 'core', 'grain', 'berry') are bacteria of the genus Streptococcus from the family of the Streptococcaceae , coccal (approximately spherical), preferably arranged in chains, gram-positive and aerotolerant . They were first discovered in 1874 by Theodor Billroth (from whom they got their name) and Paul Ehrlich as chain-forming cocci. Of the streptococci divided into groups A to T, β-haemolytic streptococci of group A (GBA) and group B (GBS) are of particular importance for humans .

properties

Spherical to ellipsoidal cells , diameter 0.5–2.0 µm, arranged in pairs or in chains of different lengths, gram-positive , non- motile (without active movement), not forming spores , some species form mucous membranes . They are facultative anaerobic , aerotolerant , chemoorganotrophic , fermentative , mainly utilize carbohydrates and thereby mainly form lactic acid homofermentative , catalase -negative and oxidase -negative (without catalase and oxidase activity), not proteolytic (does not break down proteins), temperature range of growth and the reproduction of most strains 25–45 ° C, optimum near 37 ° C.

Occurrence

Streptococci are widespread and occur as saprophytes in habitats that contain biogenic , organic substances , for example on plants and in dead plant material. In connection with their acid formation, this is used to preserve plant material ( silage , pickled vegetables ) and to manufacture sour milk products . Some streptococci belong to the normal bacterial society that settles in and on humans and mammals . The Streptococcus species that belong to the normal flora of humans are found mainly in the oropharynx , intestines and genital tract. Some streptococci can cause mild to severe illnesses in animals and humans, examples: Streptococcus pyogenes as a pus pathogen , Streptococcus mutans as a caries cause . The presence of streptococci in the blood causes sepsis (blood poisoning).

Classification, medical significance

The various hemolysis types

The classification is based on the hemolytic behavior (dissolution of erythrocytes ) into α-, β- and γ-hemolytic streptococci. β-hemolytic streptococci are further subdivided according to the Lancefield classification. Some types of streptococcus come in many forms with different types of antigens . Thus, 84 different strains of Streptococcus pneumoniae are known, which differ in the chemical structure of their polysaccharide shell . Each of these strains represents a different serotype . The polysaccharide shell of S. salivarius, for example, consists of a polymer of fructose (a so-called Laevan , the shell is therefore called the Laevan capsule ).

As viridans streptococci streptococci are referred to that in blood agar , a so-called α- hemolysis cause ( "greening"), which means they destroy the erythrocytes (red blood cells) with degradation of hemoglobin , with greenish-products. They belong to the normal colonization of microorganisms in the oral cavity . Many of them can lead to inflammation of the inner lining of the heart (endocarditis) if they enter the blood . They also include the species Streptococcus mutans , which plays an important role in dental caries (dissolution of tooth substance) by forming firmly adherent exopolysaccharides on the one hand and lactic acid from carbohydrates on the other , which attacks the tooth substance . Streptococci also cause ear, nose and throat diseases (ENT diseases).

Serogroup B β-hemolytic streptococci can pose a risk to newborns during childbirth. These bacteria can be transmitted from the mother during vaginal delivery. These bacteria can lead to sepsis , meningitis (meningitis) and pneumonia , especially in premature babies . These bacteria are detected by a smear in the vaginal or perineal area. Treatment is carried out for the period of delivery (from the rupture of the bladder or when the first labor begins) by administering antibiotics to the woman giving birth.

There are two prevention strategies: to test all laboring women and give antibiotics in the event of infection (test strategy) or to give antibiotics to all women who are at increased risk (risk strategy). The IGeL monitor of the MDS association (Medical Service of the Central Association of Health Insurance Funds) evaluates the streptococcal test during pregnancy with regard to the question "Can the test contribute to the fact that fewer newborns become infected with B-streptococci?" As "unclear". The B streptococcal test is only provided by the statutory health insurance companies in Germany if the risk is high.

γ-haemolytic streptococci show no haemolytic behavior. Serogroup D streptococci are usually treated as a separate entity (see Enterococci ).

The type of antibiotic treatment for streptococcal infections depends on their group or species.

species

Use

Streptococci are used for the production of pickled vegetables, silage and sour milk products (see under Occurrence ). The enzyme streptokinase , which is used as a fibrinolysis activator during fibrinolysis (dissolution of fibrin ), is obtained from streptococci . See also BLIS as a prophylaxis against periodontal disease and to build up the intestinal flora after antibiotic therapy or treatment of mycoses .

See also

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. 267.
  • Werner Köhler : History of streptococcal research. Erfurt 2003.
  • Ralf Vollmuth : Streptococci, Streptococcus. In: Werner E. Gerabek , Bernhard D. Haage, Gundolf Keil , Wolfgang Wegner (eds.): Enzyklopädie Medizingeschichte. De Gruyter, Berlin / New York 2005, ISBN 3-11-015714-4 , p. 1364.

Web links

Wiktionary: Streptococci  - explanations of meanings, word origins, synonyms, translations
Commons : Streptococcus  - Collection of pictures, videos and audio files

Individual evidence

  1. ^ Wilhelm Gemoll : Greek-German school and hand dictionary. Munich / Vienna 1965.
  2. ↑ Stefanie Uibel, Johanna Bock, David A. Groneberg: Streptococci - an overview . In: Zentralblatt für Arbeitsmedizin, Arbeitsschutz und Ergonomie . tape 62 , no. 6 , 2012, p. 320-327 , doi : 10.1007 / BF03346172 .
  3. ↑ John G. Holt, Noel R. Krieg, Peter HA Sneath, James T. Staley, Stanley T. Williams (Eds.): Bergey's Manual of Determinative Bacteriology . 9th edition. Williams & Wilkins, Baltimore et al. O. 1994, ISBN 0-683-00603-7 , pp. 532-533, 535-536, 552-558.
  4. ^ Marianne Abele-Horn: Antimicrobial Therapy. Decision support for the treatment and prophylaxis of infectious diseases. 2009, p. 267.
  5. ↑ IGeL-Monitor, Evaluation of the Streptococcus Test in Pregnancy , accessed on October 19, 2018.
  6. ↑ Uwe Groß: Short textbook medical microbiology and infectious diseases . 3rd, completely revised and updated edition. Thieme, Stuttgart 2013, ISBN 978-3-13-141653-7 , pp. 50 .
  7. ^ H. Hof: Medical Microbiology. 3. Edition. Thieme, 2005.
  8. ^ 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 , pp. 230-232 and 267.
  9. ↑ JP Burton, CN Chilcott, JR Tagg: The rationale and potential for the reduction of oral malodour using Streptococcus salivarius probiotics . In: Oral Diseases . tape 11 , s1, 2005, p. 29-31 , doi : 10.1111 / j.1601-0825.2005.01084.x .
  10. ↑ JP Burton, CN Chilcott, CJ Moore, G. Speiser, JR Tagg: A preliminary study of the effect of probiotic Streptococcus salivarius K12 on oral malodour parameters . In: Journal of Applied Microbiology . tape 100 , no. 4 , 2006, p. 754–764 , doi : 10.1111 / j.1365-2672.2006.02837.x (free full text).
  11. ↑ Jeremy P. Burton, Philip A. Wescombe, Chris J. Moore, Chris N. Chilcott, John R. Tagg: Safety Assessment of the Oral Cavity Probiotic Streptococcus salivarius K12 . In: Applied and Environmental Microbiology . tape 72 , no. 4 , 2006, p. 3050-3053 , doi : 10.1128 / AEM.72.4.3050-3053.2006 , PMID 16598017 (free full text).
  12. ↑ H.‐P. Horz, A. Meinelt, B. Houben, G. Conrads: Distribution and persistence of probiotic Streptococcus salivarius K12 in the human oral cavity as determined by real-time quantitative polymerase chain reaction . In: Oral Microbiology and Immunology . tape 22 , no. 2 , 2007, p. 126-130 , doi : 10.1111 / j.1399-302x.2007.00334.x .