Pathogens of malignant edema
Animal Diseases - Due to - Infectious Diseases - Malignant edema
Malignant wound gas swelling (Oedema malignum) - this name is understoodsporadically occurring acute infectious disease of cattle, sheep, goats, pigs and horses, and in northern areas and deer. This disease is also characteristic of humans and birds.
Information about the pathogen. Currently, it is believed that the causative agentmalignant wound gas edema is several microorganisms - anaerobes. Of these, Vibrin septique Pasteur (Bacillus oedematis maligni Koch, Clostridium oedematis maligni Bergey, Pararauschbrand bacillus) and, more rarely, other microbes. These microorganisms are widespread in nature, their spores are found in the treated soil, dust, senatus, intestines of healthy animals and in the corpses of animals that have fallen from malignant edema. V.septique was discovered by Pasteur in 1877. For a long time there were very contradictory ideas about it, which was explained by the fact that the authors dealt with unclean strains of this microbe. At the present time his personality is firmly established.
He meets sick animals in the form of separaterods of various sizes, in pairs and even long threads and chains. It is also characteristic of the presence in the smears of bulbous, swollen, intensely colored forms. Capsules do not form. It is painted by all aniline paints and by Gram. In young cultures and in material from patients, it is mobile. Mobility depends on the peri-trichial location of the flagella. Forms disputes. Spores are oval in shape and are usually located eccentrically, but are also located centrally. During spore formation, it swells, resulting in the formation of microbial-like or lemon-like forms. Most often, this can be observed on media rich in proteins or in material from patients. When cultivated on solid media, the microbe usually grows in a continuous layer, and dried arenas should be used to study individual colonies. Colonies are transparent, slightly opalescent, with smooth or jagged edges. Strict anaerobe. The microbe has a high activity, it develops rapidly on suitable nutrient media with the formation of a large amount of gas. Refers to the sugar group of anaerobic agents of wound infections. Ferment with formation of gas glucose, levulose, galactose, maltose, lactose and salicin, does not ferment glycerin, sucrose, mannitol and dulcite. It liquefies gelatin. The milk forms acid and coagulates it, but coagulation does not occur until 3-6 days. The cultures produce a sharp smell, reminiscent of the smell of butyric acid. The temperature optimum is 35-37 °, but it also grows at 20-23 °. Forms a toxin. The maximum toxicity is 24-48 hours. The toxin is unstable. Serologically (according to the agglutination reaction), there are 3 groups, but the toxin in all of them is identical.
In addition to these pathogens with malignant wound gas edema, Cl.perfringens and Bac.hystoliticus are also found.
Epizootic characteristic. In nature, V. septique is very widespread, is a permanent inhabitant of the intestines of all animals, from where it enters the soil and enters. Pathogen for all laboratory animals. With natural infection, the disease is most often observed in horses, then in sheep. Cattle get sick incomparably less often. Pigs and dogs are particularly resistant. Infection occurs when the skin or mucous membranes are injured, sometimes during childbirth and during such operations as castration. Especially easy is infection, when the injury is accompanied by a bruise or crushing of the underlying tissues.
Pathogenesis. The gateway of the infection is wounds, most often the skin, rarely the mucous membranes of the oral cavity, pharynx, birth canal, connective tissue and musculature. The development of the disease is facilitated by the penetration into the wounds simultaneously with the pathogens, the edema of foreign bodies (manure, earth, etc.). In these cases, in the affected tissues due to the action of toxins, necrotic processes develop, accompanied by the breakdown of carbohydrates and the formation of gases. Here there is a sharp edema - serous inflammation. Susceptibility to malignant edema does not depend on the age of the animals, although in cows older than 3 years this disease is more common than in younger animals. Particularly often, malignant edema is observed after calving during the arrest of the afterburn, which is separated with dirty hands or instruments, after abortions sheep, and also after castration.
In pigs, the disease is typicalwound infection, but can also occur in the form of acute gastritis, when bacteria, penetrating into the mucous membrane of the stomach, can cause gas edema of the walls of the stomach.
With the penetration of pathogens through the wounds, swelling develops after 24 hours.
Pathological changes. With the veterinary examination of the carcasses and organs of the deadanimals, patients with malignant edema, testicular creping swelling of the skin is observed at the site of penetration of pathogens. The subcutaneous and intermuscular tissues are strongly thickened and saturated most often with a serous, sometimes reddish and even a dark red fluid containing gas bubbles. The surrounding muscles of this area are also changed and painted dark brown, sometimes black.
Regional lymph nodes are enlarged and swollen. In the liver and kidneys, it is possible to find post-mortem developing gray, necrotic areas pierced with vesicle vesicles. There are usually no changes in the spleen; intestines - in a state of catarrhal enteritis. The heart muscle is flabby and is in a state of further parenchymal granular degeneration. In the cavities of the heart clots of coagulated blood. The lungs are stagnant and hyperemic, edematous.
When differential diagnosis it is necessary to exclude the following diseases: emphysematous carbuncle, which is characterized by clinical and pathological signs similar to those with malignant edema; anthrax, in which also subcutaneous fat can be swelling. An accurate diagnosis of malignant edema can be made only on the basis of bacteriological research.
Veterinary and sanitary examination. Animals that have a malignant edema are not allowed to slaughter, but are treated.
With postmortem detection of a malignantwound gas swelling, according to existing rules, the use of meat of these animals is prohibited. Pathogens of malignant edema are almost always found in the contents of the gastrointestinal tract of healthy people and animals. With repeated feeding of infectious material obtained from patients with malignant edema of animals, horses, cattle, sheep and goats of diseases they could not be called. It is necessary to assess the meat obtained from animals with malignant edema and perform a differentiation; when slaughtering animals with the initial disease processes, the pathologically altered parts must be destroyed, and healthy ones should be let out after preliminary provarking them, and such carcasses should be boiled as quickly as possible. Animal carcasses with extensive pathological changes should be directed to utilization. Skins after disinfection by pickling can be used in industry.
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