Clostridium perfringens
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Clostridium perfringens |
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| ( Veillon & Zuber 1898) Hauduroy et al. 1937 |
Clostridium perfringens ( Latin perfringere , 'to break through') is a rod-shaped, gram-positive , endospore-forming , uncultivated bacterium of the genus Clostridium . In (older) specialist literature, the term " Welch-Fraenkel gas bacillus " or Clostridium welchii is occasionally found .
Occurrence
C. perfringens is a strict anaerobe , but it can easily survive brief exposure to an oxygen-rich atmosphere. The organism can be detected in the soil (anaerobic zones), in water, dust and food, but also in the intestines of humans and animals (1,000 to 10,000 germs / g faeces ). In the soil, clostridia are among the most important anaerobic cellulose- degrading microorganisms.
The temperature optimum of C. perfringens is approx. 43 to 47 ° C (with generation times of 8 to 12 min), extreme range min. at 10 to 18 ° C and max. at 50 to 52 ° C. Depending on various environmental factors, the spores can survive temperatures of 60 ° C. The heat resistance is very variable depending on the trunk and can be up to 60 minutes at 100 ° C. The toxin is heat-labile (4 min at 60 ° C). The decimal reduction times are 15 to 145 minutes at 90 ° C and 0.31 to 38 minutes at 100 ° C.
Toxins
C. perfringens of serotypes A, B, C, D and E forms exotoxins ( enterotoxins ) that are pathogenic for humans . By detecting the essential toxins α , β, ε, ι, these C. perfringens serotypes can be differentiated. Gas fire germs form at least twelve toxins which act as enzymes ( proteases , collagenases , deoxyribonucleases and phospholipases ). These enzymes break down tissue and lead to necrosis in the affected muscle tissue .
Pathogenesis and pathology
The pathogen, along with other clostridia, belongs to the group of gas burn bacilli and is the most common cause of gas burn (70 to 80%). In addition, the bacterium is often the cause of necrotizing pneumonia , gangrenous cholecystitis , sepsis or other non-specific infectious diseases. In human medicine , type A and type C are particularly important. In addition, Clostridium perfringens can cause infectious diseases of the central nervous system , the most common of which is clostridial meningitis , which usually develops from clostridial sepsis, but can also arise as a result of local trauma or operations such as the removal of a subdural hematoma . Cases of clostridial encephalitis have also been described less frequently . In animals, diseases caused by Clostridium perfringens toxins are known as enterotoxemia .
Gas fire
The gas fire caused by Clostridium perfringens is considered to be the most severe form of clostridial disease and is also known as "clostridial myositis", "clostridial myonecrosis" or gas gangrene. The disease usually develops after injuries with infection during gardening or activities in the agricultural sector, but also after bite injuries or amputations and has an incubation period of approx. 2 days. The infection area is characterized by swelling and brownish-livid discoloration. In the palpation a "crackle" (may optionally Crepitatio ) are detected. Often smelly, serous wound secretion is emptied from the wound. If treatment is not carried out quickly, a toxin-induced shock can kill the infected person within hours. Despite optimal therapy, lethality is high and is 40 to 60%. However, due to good surgical care, the disease has become rare in the Federal Republic of Germany ; In 1998 there were 114 reported cases of gas fires in Germany.
Serotype A Clostridium perfringens bacteria can be detected as the pathomechanical cause of the gas fire. These destroy by their α-toxin - a lecithinase , the membrane- lecithin in phosphorylcholine and diacylglycerol splits - the cell membranes from the infected area. The multiplication of the toxin-producing pathogens or the germination of the spores of C. perfringens is stimulated by a reduction in the redox potential in the tissue - for example in the event of reduced blood flow, accumulation of secretions or necrosis . As a result, bruises, soiled abrasions, large wound cavities after amputation or impaling wounds promote infection.
Intestinal infections
C. perfringens is also one of the food poisoners. The infectious dose is 700,000 individuals / g, which is usually even higher for food. Food at risk is meat that has been kept warm (beef, poultry), oysters and other seafood. The intestinal C. perfringens diseases are caused in the majority of cases by C. perfringens strains of type A. In the United States , Clostridium perfringens is the leading reported cause of food poisoning, with an estimated 248,000 cases each year. The clostridia, which germinate after consumption, start producing the perfringens enterotoxin in the intestine, which increases the permeability of the intestinal epithelium and thus leads to diarrhea and intestinal cramps, but is rarely accompanied by fever or vomiting. The first symptoms appear within 7 to 15 hours after consuming the contaminated food and often go away after 24 hours. The lethality is low.
Much more serious by C. perfringens and triggered the first time in humans is First World War described enteritis necrotizing (also called bowel fire ) which is a highly necrotizing disease of the jejunum (upper small intestine) is. This is caused by β-toxin-producing strains of the bacterium of serotype C and is often fatal. The exact pathomechanisms have not yet been conclusively clarified. In the animal kingdom, type C causes necrotizing intestinal inflammation in suckling pigs or necrotic enteritis in lambs, sheep and calves.
diagnosis
Food poisoning by means of Clostridium perfringens type A is diagnosed by isolating the pathogen from the intestine or, most reliably, by an enzyme-linked immunosorbent test ( ELISA ) to detect the bacterium in the intestine. However, a laboratory diagnosis can usually only allow subsequent confirmation of the infection, since the symptoms of the disease have usually subsided after 24 hours.
The diagnosis of gas fire is first made clinically. Due to the rapid progression of the gas fire, it is generally not possible to wait for the pathogen to be cultivated and can therefore only be used for subsequent confirmation.
Microbiological evidence
The detection of Clostridium perfringens is first carried out microscopically by making a gram-stained preparation in which about 4 to 6 × 1 μm large rods with rounded ends are visible. In original preparations, the pathogens can be partially surrounded by capsules, which can be recognized by non-stained areas around the bacteria. Spores are occasionally found in stool and soil samples, but mostly not in cultivated cultures. The feature is u. a. the immobility due to the lack of flagellation and the lack of spore formation in vitro .
Furthermore, the suspect material is grown on anaerobic or standard blood agar and on egg yolk agar. Clostridium perfringens colonies are usually visible after 10 to 12 hours when incubated. Characteristic of anaerobic blood agar are round, convex, moist, shiny, occasionally reddish shimmering colonies 3 to 5 mm in diameter, which first turn gray, then light brown and later greenish under the influence of oxygen and are not surrounded by a large hemolytic field . Double zone hemolysis occurs around the colonies on the standard blood agar. On egg yolk agar, the lecithinase released by the pathogen causes a characteristic whitish lightening around the growth lawn ("Seiffert-Nagler reaction"). In nutrient bouillons , turbidity with strong gas development occurs quickly.
In special laboratories, the serotypes of Clostridium perfringens can also be determined by identifying the exotoxins in animal experiments using specific antisera .
Individual evidence
- ↑ a b c d e f g h Arne C. Rodloff: Obligate anaerobic spore-forming rods. In: Helmut Hahn et al. (Ed.): Medical microbiology and infectiology. 5th edition. Berlin / Heidelberg 2004, p. 339ff.
- ↑ a b c Werner Köhler: Spore-forming gram-positive bacteria (Bacillus, Clostridium) - anthrax, tetanus, gas burn, pseudomembranous colitis, botulism. In: Werner Köhler et al. (Ed.): Medical Microbiology. 8th edition. Jena / Munich 2001, p. 402ff.
- ↑ a b Gerhard Ruckdeschel: Clostridium perfringens and other histotoxic and other, usually apathogenic types of clostridia. In: Friedrich Burkhardt (Hrsg.): Mikrobiologische Diagnostik. Stuttgart / New York, p. 228ff.
- ↑ J. Finsterer, B. Hess: Neuromuscular and Central Nervous System Manifestations of Clostridium perfringens Infections . In: Infection . tape 35 , no. 6 , 2007, p. 396-405 , doi : 10.1007 / s15010-007-6345-z .
- ↑ a b c Michael T. Madigan, John M. Martinko: Brock. Microbiology. 11., revised. Edition. Munich et al. 2006, pp. 814, 1069.
- ↑ a b Herbert Hof: Bacteriology. In: Herbert Hof, Rüdiger Dörries (Ed.): Microbiology. (= Dual row ). Stuttgart 2005, p. 345ff.
- ^ Hans Adolf Kühn: Enteritis necroticans (intestinal burn). In: Ludwig Heilmeyer (ed.): Textbook of internal medicine. Springer-Verlag, Berlin / Göttingen / Heidelberg 1955; 2nd edition ibid. 1961, p. 812 f.
