Clostridium septicum

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Clostridium septicum
Clostridium septicum Light microscope picture after staining with methylene blue

Clostridium septicum
Light microscope picture after staining with methylene blue

Systematics
Department : Firmicutes
Class : Clostridia
Order : Clostridiales
Family : Clostridiaceae
Genre : Clostridium
Type : Clostridium septicum
Scientific name
Clostridium septicum
( Macé 1889) Ford 1927

Clostridium septicum is a gram-positive bacterium from the genus Clostridium and the pathogen of several infectious diseases , such as gas blight in humans, para blight in animals (e.g. in cattle and sheep ) and abomasum blight in sheep . The cells are strictly anaerobic , so they can only multiply when there is no oxygen . In Clostridium septicum is a spore-forming bacterium whose spores are resistant to heat. The bacterium was discovered in 1877 by Louis Pasteur and Jules Joubert, they named it " Vibrion septique ".

features

Appearance

Clostridium septicum is a gram-positive , medium-length, rod-shaped bacterium. A single cell is 3.0-14.0 µm (micrometers) long and 1.1-1.6 µm wide. The cells are capable of active movement through peritrichally arranged flagella . The bacterial cell wall is not surrounded by a capsule . Under unfavorable environmental conditions, clostridia are able to form endospores ; these are larger than the vegetative cell and lead to a bulge in the mother cell. Furthermore, the spores are characterized by their thermal resistance, while most vegetative bacterial cells are killed by briefly heating them to temperatures of around 80 ° C (known as pasteurization ), this heating does not damage the endospores, they are still viable and can germinate again. The endospores of C. septicum are only inactivated by heating at 100 ° C for 20 minutes.

Colonies of Clostridium septicum on solid nutrient medium

After incubation, visible colonies grow on solid nutrient media due to the multiplication of the cells , which when viewed from above do not appear circular but rather amoeboid . Due to the flagella of the bacteria, Clostridium septicum has a tendency to swarm over the surface of the culture medium. In these cases no single colonies can be identified. The entire surface is covered with a “bacterial lawn”, which makes a quantitative determination of the germ count difficult.

Growth and metabolism

As typical representatives of the clostridia , they grow anaerobically , so they can only multiply if there is no oxygen , as this has a toxic effect on the cells . As anaerobes, they are catalase- negative and oxidase -negative. The optimum temperature for the cultivation of C. septicum is around 37 ° C, so the bacterium is one of the mesophilic organisms. The optimal pH value for the growth of most of the strains examined is in the neutral range (pH 7.0 to 7.2).

The bacterium can be cultivated in a nutrient medium which, in addition to carbohydrates (mostly glucose ), also contains meat extract , yeast extract , peptone or amino acids , vitamins and other complex growth factors (e.g. heme and various minerals ). Since oxygen is toxic to the cells of C. septicum , the medium must be anoxic prior to inoculation . This is achieved by boiling and cooling under a nitrogen atmosphere . Strict adherence to the anaerobic technique must also be observed during inoculation and incubation .

genetics

The genome of a strain of Clostridium septicum has been completely sequenced , but according to the institute involved it is still in the draft status . Several DNA sequences that encode the pathogen's virulence factors have already been examined between 1993 and 2011 and form the basis for his detection methods.

Pathogenicity

Proposed crystal structure of the alpha toxin protein

Clostridium septicum is pathogenic; it is  assigned to risk group 2 by the Biological Agents Ordinance in conjunction with TRBA 466 . It is the causative agent of several infectious diseases in humans and animals.

The pathogenicity of Clostridium septicum is based on the release of exotoxins , similar to Clostridium botulinum and the botulinum toxin it produces . The α-toxin, which is important for C. septicum, is responsible for the symptoms of the infectious disease gas fire . It is one of the cytolytic toxins (cytotoxins), as its effect leads to the lysis ("dissolution") of the cells. In infected cells, the toxic protein leads to the formation of ion- permeable channels in the cell membrane . In the cell cultures examined , this quickly leads to cell death ( necrosis ) due to the outflow of potassium ions. Further studies cite the influx of calcium ions through the ion channels as the cause of the necrosis . When infected with gas fire, the alpha toxin also damages erythrocytes , so that it is regarded as a lethal toxin due to its hemolytic and necrotizing effects.

proof

To be able to detect the bacterium, it must be cultivated. The nutrient requirements of the nutrient medium are high, it must contain numerous complex growth factors . In addition, the anaerobic technique must be used for inoculation and incubation. The cultural detection is always time-consuming, since the reproduction of the bacteria on the nutrient medium takes several days until visible colonies are formed. Detection methods are then added. However, cultural evidence is often required to ensure identification of the bacterium in a sample and to have pure cultures available for studies.

In the case of clinical samples, for reasons of time, it is necessary to achieve faster identification so that therapeutic measures, such as treatment with antibiotics , can be carried out as soon as possible . For this purpose, direct immunofluorescence is used, in which antibodies are marked with fluorescent dyes . The antigen to be examined is part of the bacterium. The labeled antibodies bind to the antigens ( antigen-antibody reaction ) and the bacteria are detected directly in the fluorescence microscope .

Among the animal diseases, the infectious diseases that can be found in cattle and sheep are indistinguishable from the symptoms of intoxicating blight (caused by Clostridium chauvoei ) and pararous blight (caused by C. septicum ). Therefore, the detection of the bacteria is important. As the two species are phenotypically very similar, the Friedrich Loeffler Institute (FLI) - Federal Research Institute for Animal Health - has developed a multiplex PCR process. It is based on the detection of the "spo0A gene" and makes it possible to identify C. chauvoei and C. septicum in clinical samples at the same time . The method has been used at the Institute for Bacterial Infections and Zoonoses , a research facility of the FLI, since 2010 . For Germany the institute is the national reference laboratory for intoxicating fire .

When examining poultry flocks for the presence of C. septicum as a pathogen, tissue samples are used as the test material. As an alternative to cultural evidence, the alpha toxin formed by the pathogen is examined. The aim of the investigation is that part of the genome in which toxin formation is coded . The detection is carried out with the help of the real-time PCR process, which enables the differentiation from other toxins that are formed by related Clostridium species.

Occurrence

Clostridium septicum occurs in the soil, from where it is further spread with the help of the endospores. While the vegetative cells react sensitively to atmospheric oxygen, this does not apply to the endospores, so that they are ubiquitous and can be found almost everywhere. In the case of animal diseases, the distribution of the endospores on forage plants is important. In infected people or animals, various types of tissue or organs are affected, for example the intestines or the abomasum in ruminants , in which the bacterium can then be detected.

Systematics

External system

The utilization of carbohydrates in clostridia occurs through fermentation . The first step is the gradual breakdown of monosaccharides (simple sugars) such as B. D - Glucose (grape sugar) in glycolysis to pyruvate . Under anaerobic conditions, the NAD + (nicotinamide adenine dinucleotide) consumed in the process must be regenerated; this is done by means of butyric acid fermentation or other fermentations. In addition to the saccharolytic clostridia (which mainly ferment carbohydrates) there are also clostridia which break down amino acids, peptones or proteins in a fermentation process; they are referred to as peptolytic or proteolytic clostridia. In many of these fermentations, butyrate (the anion of butyric acid ), acetate (anion of acetic acid), carbon dioxide (gas) and gaseous hydrogen (H 2 ) are the characteristic products of fermentation. The gas fire pathogens include both sugar and amino acid fermenters.

The distinction between Clostridium chauvoei (causative agent of intoxicating blight) and Clostridium septicum (causative agent of pararous blight) is difficult, as the two species are similar in many phenotypic characteristics. In fact, genetic studies have shown that 99.3% of the nucleotides in the genome of C. chauvoei and C. septicum are identical.

etymology

The generic name can be traced back to the appearance of the spindle-shaped bacterial cells that are expanded by the endospores (from ancient Greek for "spindle"). The species name refers to the Greek word σῆψις sēpsis and means "putrefaction", it can also be found in the term sepsis (blood poisoning) as a disease symptom. The bacterium was discovered in 1877 by Louis Pasteur and Jules Joubert in anthrax carcasses, and they named it “ Vibrion septique ”.

Medical and veterinary importance

Sources of infection

The infection of C. septicum can orally take place, this particular is among the animal diseases of importance. The cause here is feed contaminated with endospores. In organs with anaerobic conditions, such as the intestine, the spores can germinate and develop into vegetative cells, which, if they are high enough, cause infection. An important source of infection is soil ("earth"), a so-called exogenous infection is the result when dirt gets into a deep wound, similar to tetanus ( tetanus ). Endogenous infections are also observed - especially in patients with a weakened immune system or in patients with colorectal carcinoma (colon cancer) - in this case, clostridia in the intestine spread to other tissues.

Infectious diseases in humans

In humans, the infectious disease gas fire (other names include gas edema , clostridial myositis and clostridial myonecrosis ) is mainly caused by Clostridium perfringens , but C. septicum is one of the pathogens of this disease. It is a local soft tissue infection with gas-forming clostridia. The metabolism of the bacteria creates gas (carbon dioxide) that destroys the surrounding tissue and can be felt as a gas accumulation under the subcutaneous tissue . The exotoxins formed by C. septicum lead to necrosis of the tissue, which then enables the bacteria to multiply further, since there is no longer any oxygen supply via the blood. The course of the disease is often very short; after an incubation period of five hours, death can occur after just a few hours if no treatment is given. But even with therapy, the mortality rate of this disease is 40–60%.

If C. septicum is the pathogen, the mortality rate is often even higher. Children in particular are at risk, as the first unspecific symptoms often do not lead to the correct diagnosis . The gastrointestinal tract is often affected. One case study cited symptoms of vomiting , diarrhea , blood in the stool, abdominal pain and loss of appetite , which occurred in 85% of children with the disease.

Infectious diseases in animals

Clostridium septicum causes the infectious disease Pararauschbrand in cattle , sheep and goats . The symptoms are the same as those of the animal disease bogus , which is caused by C. chauvoei , and are similar to the gas burn in humans. In sheep, C. septicum v. a. Abomasum and abomasum intoxication are also known and are known as abomasum intoxication of sheep or Nordic bradsot . It occurs predominantly in young animals between the ages of six months and two years and is characterized by the peracute course with fever and a high mortality rate: up to 50% of infected sheep die within a few hours. Furthermore, C. septicum the trigger of an infectious disease of poultry known as gangrenous dermatitis is called.

therapy

Treatment is difficult because of the rapid progression of infections caused by Clostridium septicum . In humans, in addition to surgical interventions , e.g. B. Amputation of affected limbs, antibiotics used as an accompanying measure to combat the pathogens. Penicillin G ( benzylpenicillin ) is mainly used, but also cephalosporins . When the animal diseases occur, sick animals must be isolated, the other animals are vaccinated with a polyvalent clostridial vaccine .

swell

literature

  • Michael T. Madigan, John M. Martinko, Jack Parker: Brock Microbiology. German translation edited by Werner Goebel, 1st edition. Spektrum Akademischer Verlag GmbH, Heidelberg / Berlin 2000, ISBN 978-3-8274-0566-1 .
  • Hans G. Schlegel, Christiane Zaborosch: General microbiology . 7th edition. Thieme Verlag, Stuttgart / New York 1992, ISBN 3-13-444607-3 .

Individual evidence

  1. ^ A b c Hans G. Schlegel, Christiane Zaborosch: General microbiology . 7th edition. Thieme Verlag, Stuttgart / New York 1992, ISBN 3-13-444607-3 .
  2. ↑ a b c d Martin Ganter, Heinrich Behrens, Theodor Hiepe: Textbook of sheep diseases . 4th edition. Parey Verlag, Stuttgart 2001, ISBN 978-3-8304-4190-8 .
  3. ↑ a b c A. P. Neumann, SM Dunham u. a .: Quantitative real-time PCR assay for Clostridium septicum in poultry gangrenous dermatitis associated samples. In: Molecular and cellular probes. Volume 24, Number 4, August 2010, pp. 211-218, ISSN  1096-1194 . doi : 10.1016 / j.mcp.2010.04.001 . PMID 20399850 .
  4. ↑ a b c Catalog of Microorganisms. In: Website of the Leibniz Institute DSMZ - German Collection of Microorganisms and Cell Cultures GmbH . Retrieved August 11, 2013 .
  5. ↑ a b S. M. Hasan, JB Hall: Growth of Clostridium tertium and Clostridium septicum in chemically defined media. In: Applied and environmental microbiology. Volume 31, Number 3, March 1976, pp. 442-443, ISSN  0099-2240 . PMID 180884 . PMC 169793 (free full text).
  6. ↑ Clostridium septicum. In: Website Genomes Online Database (GOLD) . Retrieved August 11, 2013 .
  7. ^ Projects. In: Website Hattori Lab in the University of Tokyo . Retrieved August 11, 2013 .
  8. ↑ Clostridium septicum (Taxon Passport). (No longer available online.) In: StrainInfo website . Archived from the original on March 4, 2016 ; Retrieved August 11, 2013 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / www.straininfo.net
  9. ↑ TRBA 466: Classification of prokaryotes (Bacteria and Archaea) in risk groups. In: Website of the Federal Institute for Occupational Safety and Health (BAuA). May 4, 2012, accessed August 6, 2013 .
  10. ↑ a b c d e Michael T. Madigan, John M. Martinko, Jack Parker: Brock Mikrobiologie. German translation edited by Werner Goebel, 1st edition. Spektrum Akademischer Verlag GmbH, Heidelberg / Berlin 2000, ISBN 978-3-8274-0566-1 .
  11. ^ O. Knapp, E. Maier u. a .: Clostridium septicum alpha-toxin forms pores and induces rapid cell necrosis. In: Toxicon: official journal of the International Society on Toxinology. Volume 55, Number 1, January 2010, pp. 61-72, ISSN  1879-3150 . doi : 10.1016 / j.toxicon.2009.06.037 . PMID 19632260 .
  12. ↑ CL Kennedy, DJ Smith et al. a .: Programmed cellular necrosis mediated by the pore-forming alpha-toxin from Clostridium septicum. In: PLoS pathogens. Volume 5, Number 7, July 2009, p. E1000516, ISSN  1553-7374 . doi : 10.1371 / journal.ppat.1000516 . PMID 19609357 . PMC 2705182 (free full text).
  13. ^ TI Cortiñas, MA Mattar, AM Stefanini de Guzmán: Alpha-toxin production by Clostridium septicum at different culture conditions. In: Anaerobic. Volume 3, Numbers 2-3, 1997 Apr-Jun, pp 199-202, ISSN  1075-9964 . doi : 10.1006 / anae.1997.0105 . PMID 16887590 .
  14. ↑ a b National Reference Laboratory for Rauschbrand. (No longer available online.) In: Website of the Friedrich Loeffler Institute (FLI). Archived from the original on May 4, 2014 ; Retrieved August 11, 2013 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / www.fli.bund.de
  15. ↑ M. Lange, H. Neubauer, C. Seyboldt: Development and validation of a multiplex real-time PCR for detection of Clostridium chauvoei and Clostridium septicum. In: Molecular and cellular probes. Volume 24, Number 4, August 2010, pp. 204-210, ISSN  1096-1194 . doi : 10.1016 / j.mcp.2010.03.003 . PMID 20362050 .
  16. ↑ P. Kuhnert, SE Capaul u. a .: Phylogenetic positions of Clostridium chauvoei and Clostridium septicum based on 16S rRNA gene sequences. In: International journal of systematic bacteriology. Volume 46, Number 4, October 1996, pp. 1174-1176, ISSN  0020-7713 . PMID 8863454 .
  17. ^ Jean Euzéby, Aidan C. Parte: Genus Clostridium. (No longer available online.) In: List of Prokaryotic names with Standing in Nomenclature ( LPSN ). Archived from the original on November 3, 2013 ; Retrieved August 12, 2013 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / www.bacterio.net
  18. ^ A b c Herbert Hof, Rüdiger Dörries: Dual series: Medical microbiology . 3. Edition. Thieme Verlag, Stuttgart 2005, ISBN 978-3-13-125313-2 .
  19. ↑ CL Smith-Slatas, M. Bourque, JC Salazar: Clostridium septicum infections in children: a case report and review of the literature. In: Pediatrics. Volume 117, Number 4, April 2006, pp. E796-e805, ISSN  1098-4275 . doi : 10.1542 / peds.2005-1074 . PMID 16567392 . (Review).
  20. ↑ Official collection of methods for notifiable animal diseases, as of May 2009. (PDF; 4.1 MB) (No longer available online.) In: Website of the Friedrich Loeffler Institute (FLI). Formerly in the original ; Retrieved August 11, 2013 .  ( Page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.@1@ 2Template: Toter Link / www.fli.bund.de  

Web links

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