Pathogen anthrax - Bacillus anlhracis (Koch, 1872) is a typical representative of pathogenic bacilli. Belongs to the Bacillaceae family, genus Bacillus. This microbe is often called the anthrax bacillus.
Anthrax (Anthrax) is a zooanthroponosis. Many species of vests are susceptible, especially herbivores, and humans. The infectious process occurs predominantly acutely, with symptoms of septicemia or the formation of carbuncles of varying sizes. The disease is recorded in sporadic cases, enzootics and even epizootics are possible. The name of the disease “anthrax” was proposed in 1789 by S. S. Andrievsky, who studied it in the Urals and Siberia.
Microscopically, the anthrax bacillus was discovered by Pollender in 1849. French researchers Daven and Reis (1850), and in Russia, professor of the Dorpat Veterinary School Vrawell (1857), also established the presence of thread-like immobile and non-branching bodies in the blood of sheep sick and dead from anthrax. Browell was one of the first to identify bacilli in the blood of a man who died of anthrax, and experimentally infected animals with his blood. However, the role of these bacilli remained unclear until 1863, when Daven finally established them as the causative agents of anthrax.
Pure cultures of the anthrax bacillus were isolated in 1876. first R. Koch, and then L. Pasteur. Independently of each other, they reproduced the disease in animals using cultures of these microbes. In Russia, the first culture of the anthrax microbe was obtained by V.K. Vysokovich in 1882
R. Koch in 1876 proved that the vegetative cells of the anthrax microbe have the ability to form spores; in 1888, Serafini discovered the capsule of the microbe.
Morphology
Anthrax bacilli are rather large (1... 1.3x3.0... 10.0 µm) rods, immobile, gram-positive; form a capsule and spores (Fig. 25, 26, 27, 28). The microbe occurs in two forms: vegetative, in the form of rods of various cell sizes (capsular and noncapsular), and spore. Spores can be enclosed in a well-defined exosporium and located inside and outside the rods in the form of isolated bodies. In stained preparations from the blood and tissues of animals sick or dead from anthrax, the bacilli are located singly, in pairs and in the form of short chains (3...4 cells surrounded by a capsule). The ends of the sticks in the chains are straight, with sharply cut off ends, and the free ends are slightly rounded. Sometimes the chains are shaped like bamboo canes.
In smears from cultures, on solid and liquid nutrient media, rods are arranged in long chains.
In the body or when cultivated on artificial nutrient media with a high content of native protein, the anthrax bacillus forms a capsule.
The anthrax bacillus forms spores in the external environment under unfavorable living conditions. In each vegetative cell, only one endospore is formed, most often located centrally, less often - subterminally. The spores are oval, sometimes round. The sizes of mature spores range from 1.2...1.5 µm in length and 0.8...1.0 µm in diameter, as well as in a living organism or an unopened corpse.
Table of contents of the topic "Anthrax causative agent. Clinical manifestations of anthrax infection. Bacillus cereus.":Cultural properties of bacillus anthracis. Cultural properties of anthrax. Sporulation by anthrax. Biochemical properties of anthrax.
Bacillus anthracis grows well on ordinary nutrient media. Temperature optimum 35-37 °C; optimum pH 7.0. IN liquid media Grows in the form of cotton flakes, without causing turbidity in the medium. When sown by injection into gelatin, it produces characteristic growth in the form of an “inverted Christmas tree” (Fig. 13-4). Later, the top layer of gelatin liquefies, forming a funnel.
Anthrax on solid media forms rough, uneven, grayish-white, fibrous R-colonies with a diameter of 2-3 mm. At low magnification, the colonies resemble the “head of Medusa” or the “lion’s mane” (Fig. 13-5); characteristic appearance colonies are given intertwining chains anthrax bacteria.
Anthrax sporulation
Under aerobic conditions at 12 °C and 40 °C anthrax bacillus forms centrally located spores, 0.8-1.0x1.5 µm in size (see Fig. 4-13). In a living organism, sporulation does not occur; it is also absent in unopened corpses, which is mediated by the absorption of free oxygen during the process of decay. The spores are highly resistant to external influences: dry heat kills bacteria at 140 °C in 2-3 hours, autoclaving at 121 °C in 15-20 minutes. In water they last up to 10 years, in soil - up to 30 years. The germination rate depends on the temperature (optimum 37 °C) and the age of the spores; Young spores under optimal conditions germinate in 1-1.5 hours, old ones in 2-10 hours.
Biochemical properties of anthrax
anthrax forms acid without gas on media with glucose, fructose, maltose and dextrin. Hydrolyzes starch; forms acetoin and lecithinase. Unlike saprophytes, anthrax bacilli lack phosphatase and do not decompose phosphates contained in the nutrient medium. The milk is curdled within 3-5 days. The clot slowly peptonizes and liquefies with the release of ammonia, and also (due to the oxidation of tyrosine) turns brown.
THE CAUSE OF ANTHRAX - Bacillus anthracis, genus Bacillus Anthrax is an acute infectious disease of farm and wild animals, as well as humans, characterized by fever, septicemia, hemorrhages in tissues and organs, and the formation of carbuncles. Possible hyperacute course (CRS, MRS). In pigs it often occurs with damage to the retropharyngeal lymph nodes.
Bacillus anthracis has been described under different names since time immemorial by Homer, Hippocrates, and Celsius. In 1788, the name of the disease was given by S.S. Andreevsky - staff doctor of the Chelyabinsk district The causative agent of the disease was discovered: by A. Pallender (Germany) in 1849 by C. Daven (France) in 1850 by F.A. Brauel - professor at the Dorpat veterinary school in 1857. Anthrax was studied in detail by R. Koch ( 1876), L. Pasteur (1877) and L. S. Tsenkovsky (1883).
Morphology The causative agent is a large, immobile gram-positive rod 6-8 µm long and 1.0-1.5 µm wide. Contains a differentiated nucleoid (nucleus). In smears it is located singly or more often in chains. The ends of the bacilli in the colored preparations seem to be cut at right angles.
Defense mechanisms of the anthrax causative agent The high resistance of the anthrax causative agent to unfavorable factors is due to the fact that it forms a capsule in the body, and a spore outside the body. The capsule is formed in a susceptible and non-immune organism, and sometimes also on media supplemented with blood or serum. The capsule performs protective function and is a carrier of virulence. Noncapsular strains are avirulent. Spores appear with access to atmospheric oxygen, lack of nutrients, and even in distilled water at C. Spores are located in the middle of the microbial cell and have an oval shape. On a nutrient medium at a temperature of 37 C, young spores germinate in 1-2 hours, old ones in 5-7 hours. In chestnut and chernozem soils in the summer, spores can germinate, forming vegetative cells, which with the onset of autumn again turn into their original forms.
An ear from an animal corpse, bandaged at the base (the ear is cut off from the side on which the corpse lies), or blood from an incision in the ear in the form of a thick smear on two glass slides is sent to the laboratory. To prevent the pathogen from entering the external environment, the incision site is cauterized with a spatula. Retropharyngeal lymph nodes and areas of edematous tissue are sent from pig corpses for laboratory testing. connective tissue. If anthrax is suspected during the autopsy, it is stopped and part of the spleen is sent for examination. The native material is placed in clean containers (test tubes, jars). The dried smears are placed in Petri dishes, which are wrapped in thick paper. The packaging includes the inscription “The smear is not fixed!” The container with the material is placed in a moisture-proof container, tied, sealed or sealed, and the inscription “Top. Carefully!" and with accompanying documents are sent by express to the laboratory. Material for research
Laboratory diagnosis of the causative agent of anthrax Bacterioscopy (staining according to Mikhin, according to Olt, according to Gram) Isolation of a pure culture and identification of the pathogen according to cultural and morphological characteristics. Bioassay (2 white mice or guinea pigs) “Pearl necklace” test Phage typing Hemolytic activity (-) Reaction with anthrax luminescent serum (+) Motility (-) Precipitation reaction (RP)
Methods for staining the pathogen Smears are prepared from the material received by the laboratory and stained using Gram. To identify the capsule, smears are stained with one of the methods (Mikhin, Giemsa, Olt methods, etc.), as well as with anthrax luminescent sera. In stained smears from cadaveric material, the pathogen is detected in the form of large gram-positive rod-shaped bacteria, located singly, in pairs, or in short chains. The ends of the rods facing each other are sharply cut off, the free ends are rounded, the cells are surrounded by a capsule. IN in some cases Especially in smears from pigs, the shape of the cells may be atypical: short, thick, curved or granular rods with swelling in the center or at the ends of the bacteria. A preliminary response to the farm from which the material came is given immediately based on the results of a microscopic examination.
Cultural properties The causative agent of anthrax is a facultative anaerobe. The optimal temperature is 35-37°C. The optimum pH of the environment is 7.2-7.4. Incubate under aerobic conditions for h, and in the absence of growth - up to 48 h.
Character of growth of the pathogen On MPA, B. anthracis forms flat, matte gray, rough colonies with processes at the edges (R-form, Fig.), and can also form atypical colonies without processes. Under low microscope magnification, the edges of R-form colonies have the appearance of curls, called “lion’s mane” (Fig.). On the MPB, the growth of the pathogen is characterized by the formation of a loose sediment at the bottom of the test tube in a transparent nutrient medium; after shaking, the sediment breaks into flakes
If the pathogen is grown on nutrient media containing blood serum and in an atmosphere with a high content of carbon monoxide (IV), then smooth S-form colonies are formed on MPA, and growth in the form of diffuse turbidity of the medium is noted on MPB. In grown cultures, the morphological and tinctorial properties of cells are studied. Gram-stained smears reveal long chains of typical gram-positive rods; On serum-free media, bacteria do not form a capsule; on serum-based media, the pathogen forms a capsule, and the cells in the preparation in the latter case are often located singly or in pairs. Pathogen growth pattern
In case of significant contamination of the material with foreign microflora, inoculation is done on selective agar: molten MPA ml, polymyxin M sulfate - 0.5 ml, nevigramon - 0.5 ml, griseofulvin -1 ml, Progress detergent - 10 ml, sodium phenol phthalein phosphate - 0.1ml; mix and pour into Petri dishes. After an hour of cultivation, 1-2 ml of 25% is applied to the inner surface of the lid of the Petri dish. aqueous solution ammonia, turn the cup over. Colonies of B. anthracis remain colorless, while colonies of bacteria with phosphatase activity turn pink.
Hours before death, the animal becomes a dangerous source of disease
The spores are very persistent. They can withstand exposure to direct sunlight for days
QUARANTINE Under the terms of quarantine, it is prohibited: - entry and import, withdrawal and export outside the territory of animals of all types; - procurement and export of products and raw materials of animal origin - regrouping of animals within the farm; - use of milk from sick animals; - performing surgical operations, except emergency ones; - entry to a dysfunctional farm by unauthorized persons, entry of vehicles not related to the maintenance of this farm; - driving animals to water from ponds and other natural bodies of water.
BIOPREPARATIONS * STI vaccine (live) * VGNKI vaccine (dry, live) * Associated (live vaccine against anthrax and emphysematous carbuncle of cattle) * Vaccine from strain 55 (live) * Therapeutic and prophylactic anthrax serum * Anthrax precipitating serum * Anthrax ennobled luminescent serum * Anthrax diagnostic bacteriophage
Vaccine from strain 55 Lyophilized, in ampoules (bottles) in the form of tablets of 1-2 cubic cm (doses) for subcutaneous use Liquid in bottles of cubic cm (doses) for subcutaneous use and in ampoules of 1- 5 cc (doses) for subcutaneous or intravenous application Young animals of all types of water from 3 months of age, foals - from 9 months. Revaccination after 6 months. after the first vaccination and subsequently - annually for all animals, once a year
Vaccine from strain 55 Subcutaneous application: sheep and goats - 0.5 cc - in the middle third of the neck or inner thigh; for horses, cattle, deer, camels, donkeys – 1.0 cubic cm each – in the area of the middle third of the neck; for pigs - 1.0 cc - in the area of the inner thigh or behind the ear; for fur-bearing animals -1.0 cc – in the area of the inner thigh or in the caudal mirror
Vaccine from strain 55 Intradermally - using a needle-free injector in a volume of 0.2 cubic cm of c.p.s., for deer, camels - into the hairless area of the perineum; for horses and donkeys - in the region of the middle third of the neck of pigs - behind the ear; sheep and fur-bearing animals - in a volume of 0.1 cubic cm - in the under-tail mirror Immunity after 10 days, for 1 year
In an epizootic focus of anthrax: 1). Based on the results of a clinical examination, animals are divided into 2 groups: 1- sick animals (having clinical signs of illness or elevated body temperature. They are administered anti-anthrax serum or globulin and antibiotics. 14 days after clinical recovery, they are vaccinated anthrax vaccine. 2- the remaining animals located in the epizootic outbreak. They are vaccinated with anthrax vaccine in accordance with the instructions for its use, followed by (within 3 days) a daily clinical examination. Animals with clinical signs of the disease are transferred to group 1.
2) To care for sick and suspected animals, service personnel are assigned. He is provided with special clothing, disinfectants, first aid kits, and personal hygiene products. These individuals must be vaccinated against anthrax or undergo emergency prophylaxis. Workers who have skin lesions on their hands, face and other open areas of the body are not allowed to work on caring for sick animals, cleaning corpses, cleaning and disinfecting rooms and other objects contaminated with the pathogen. 2) Feed prepared in safe areas of crops, pastures, hayfields, not in contact with sick animals and not contaminated by their secretions, is allowed for export after quarantine is lifted (obtained from areas where animals were sick or died from anthrax, or contaminated with other way, cannot be removed from the farm; they are fed on site to animals vaccinated against anthrax).
4) During the entire treatment period, milk from animals of the first group must be destroyed after disinfection by adding bleach containing at least 25% active chlorine, at the rate of 1 kg per 20 liters of milk, and leaving for 6 hours. Milk from animals of the second group is boiled for 4-5 minutes within 3 days after vaccination and fed to vaccinated animals in the epizootic outbreak; After the specified period, the milk, under the supervision of veterinary specialists, is transported through a transshipment point to a designated creamery for processing into butter. 5) Products produced at dairy enterprises from milk received from the farm before the imposition of quarantine are sold without restrictions. 6) Manure, bedding and feed residues contaminated with secretions of sick animals are burned. Slurry in a slurry container is mixed with dry bleach containing at least 25% active chlorine, at the rate of 1 kg of lime for every 20 liters of slurry.
DISINFECTION FOR ANTHRAX To disinfect surfaces contaminated with the pathogen, use: 10% hot solution caustic soda, 4% solution of formaldehyde, solutions of bleach, two-thirds salt and neutral calcium hypochloride, DP - 2, hexanite containing 5% active chlorine, 10% iodine monochloride (only for wooden surfaces), 7% hydrogen peroxide solution with the addition of 0.2% lactic acid and 0.2% OP-7 or OP-10, 2% glutaraldehyde solution. Disinfection with the indicated agents (except for iodine monochloride, hydrogen peroxide and glutaraldehyde) is carried out three times with an interval of 1 hour at the rate of 1 liter per 1 sq. m. in standard premises and 2 liters of solution per 1 sq. m. in premises adapted for keeping animals. When using iodine monochloride, the surface is treated twice with an interval of minutes at a consumption rate of 1 l/sq.m. m. area, and hydrogen peroxide and glutaraldehyde - twice with an interval of 1 hour based on the same calculation.
To disinfect surfaces at low (minus) temperatures, use: solutions of bleach, two-thirds calcium hypochlorite salt containing 8% active chlorine, DP-2 preparation and neutral calcium hypochloride containing 5% active chlorine. Solutions are prepared before use in a hot (50-60°C) 15% (at external temperature from 0 to minus 15°C) or 20% (at temperature up to minus 30°C) solution of table salt. Solutions are applied three times with an interval of 1 hour at a consumption rate of 0.5-1 l/sq. m. To disinfect wooden surfaces use: 10% solution of iodine monochloride - three times with an interval of min. 0.3-0.4 l/sq. m., after preliminary moistening the surfaces with a 20% solution of table salt at the rate of 0.5 l/sq.m. Exposure in all cases is 12 hours after the last application of the disinfectant solution. At the end of the exposure, the feeders and drinkers are washed with water, and the room is ventilated.
The soil at the site of death, forced slaughter of a sick animal or autopsy of an animal that died from anthrax is irrigated with a solution of bleach containing 5% active chlorine at the rate of 10 l/sq.m. m.. After this, the soil is dug up to a depth of cm, mixed with dry bleach containing at least% active chlorine, based on 3 parts of soil to 1 part of bleach. After this, the soil is moistened with water. Disinfection of soil foci of anthrax is carried out with methyl bromide in accordance with current instructions. After disinfection, the soil outbreak is considered eliminated and the corresponding restrictions are lifted. Working clothes, brushes, combs, buckets and other small equipment are disinfected and disinfected by immersing for 4 hours in a 1% activated solution of chloramine, 4% solution of formaldehyde or boiling in a 2% solution of soda ash for at least 90 minutes. Fur products, leather, rubber shoes and other things that deteriorate using the above disinfection method are disinfected with formaldehyde vapor in formaldehyde steam chambers at a consumption of 250 ml. formalin per 1 cubic meter m chamber volume, temperature 58-59°C and exposure 3 hours. Valuable furs are treated in special hermetic chambers with methyl bromide (in accordance with the instructions).
Quarterly dynamics of anthrax problems (cattle, small animals, pigs, horses) for the year YearsQuarters IIIIIIIV
Quarterly dynamics of incidence of anthrax (cattle, small animals, pigs, horses) for the year Years Quarters IIIIIIIV According to IAC Rosselkhoznadzor
Anthrax (according to IAC Rosselkhoznadzor) - Situation: stationary trouble, primarily due to the presence of soil foci of infection - Vaccine dependence - Focal incidence (n = 7) = 4.1 - Registration of soil foci is not perfect. The data presented in the “Cadastre” is significantly higher than the number of recorded outbreaks in the constituent entities of the Russian Federation - During the year, the disease was registered in three constituent entities of the Russian Federation: - in pigs in Voronezh region in the first quarter (one animal fell ill); - in cattle in the Kursk region (3rd quarter) and the Republic of North Ossetia (4th quarter) - one animal each fell ill
Anthrax (according to the IAC Rosselkhoznadzor) In 2010, 11 cases of animal anthrax were registered. Problems with the disease were identified in the following regions: Republics - Dagestan (2 villages, 1 head of cattle and 1 head of small cattle fell ill), Chechnya ( 2n.p., 2 heads of cattle got sick), Kalmykia (1n.p., 1 head of cattle got sick). Stavropol Territory (1 settlement, 1 head of cattle fell ill), Krasnodar Territory (1 settlement, where 152 heads of cattle and 2 horses fell ill). Volgograd region (1 settlement, 1 head of cattle fell ill), Rostovtovsk region (1 settlement, 1 pig fell ill), Omsk region (2 settlement, 2 horses fell ill) Epidemic thresholds for ill-health and morbidity in 4- om quarter have not been surpassed. The short-term trend in ill-being is decreasing, while in morbidity it is increasing. The quarterly dynamics of troubles are extremely variable: from 0 to 8 outbreaks.
anthrax known since ancient times. Its causative agent, B. anthracis, was first described by Pollender (1849) and Daven (1850). Great contributions to the study of anthrax were made by Koch (1876), Pasteur (1881) and L. S. Tsenkovsky (1883).
Morphology and biological properties. The causative agent of anthrax (B. anthracis) is a large rod with chopped ends (on average 1.5X8 microns). In the stained preparation, the rods are arranged singly, in pairs or in a chain (Fig. 38, 1).
Gram positive. The microbe is immobile, surrounded by a transparent capsule, the formation of which is characteristic of virulent strains. The capsule is formed both in the body of sick people and animals, and during cultivation on special nutrient media. Under unfavorable environmental conditions with access to oxygen and temperatures from 15 to 42°C, the microbe forms a spore, which is located centrally and has an oval shape. Its diameter does not exceed the diameter of the cell. When hitting favorable environment spores germinate within a few hours.
The causative agent of anthrax is a facultative aerobe. The optimal growth temperature is 35–37°C and pH 7.4–8.0. The microbe is undemanding to nutrient media, so it can grow even on such substrates as straw infusion, raw and boiled potatoes, extracts of cereals, peas, etc. On meat-peptone agar, growth is so characteristic that it has diagnostic value. After 24 hours of growth, colonies appear: silver-gray, granular, 3-5 mm in diameter, with fringed edges and bundles of threads extending from them, reminiscent of a jellyfish’s head or a lion’s mane. This growth (R-form) is characteristic of virulent strains.
In old cultures, smooth S-shaped colonies appear, avirulent. After 18-24 hours, a sediment in the form of flakes forms in the broth, and the broth itself remains clear.
Biochemical activity small: decomposes glucose, maltose, sucrose with the formation of acid, milk slowly coagulates and peptonizes. The growth in the column of gelatin is characteristic: in the form of an “overturned Christmas tree”; later the gelatin liquefies in a funnel; on blood agape does not produce hemolysis, which makes it different from similar soil and pseudoanthrax bacilli. The pathogenetic factors of the anthrax pathogen are its ability to produce exotoxin and form a capsule. The inflammatory and lethal effects of the pathogen are associated with the exotoxin. It was found that the toxin also suppresses the phagocytic activity of leukocytes. The capsule prevents the phagocytosis of bacilli, promoting the manifestation of the action of the main pathogenetic factor - the toxin. The toxin causes increased vascular permeability in the body, respiratory distress due to damage to the central nervous system, changes cellular and chemical composition blood.
Sustainability. Vegetative forms are not stable: they die in a corpse within 1-3 days, at 60°C - after 15 minutes, and at 75°C - after a minute. Spores of anthrax bacilli are highly resistant. They persist in the external environment longer than all other known pathogenic spore-forming microbes. Withstand dry heat of 120-140°C for 2-3 hours, autoclaving at 120°C for 5-10 minutes. Disinfecting solutions (sublimate 1: 1000, 5% carbolic acid solution, 5-10% chloramine solution) kill them in only a few hours, and ethanol in concentrations from 25% to absolute - in 50 days.
Antigenic structure. The causative agent of anthrax contains a polysaccharide antigen and a capsular protein antigen in its cell wall. The body produces antibodies to both antigens, but they do not have protective properties. In the body of animals and humans, the microbe forms a special protective antigen, which determines the state of immunity.
Pathogenicity. Anthrax primarily affects domestic herbivores. Infection of animals occurs mainly through contaminated food, which leads to the development of the intestinal form of anthrax and is accompanied by the release of large quantity germs in feces. In laboratory conditions, guinea pigs, white mice and rabbits are most sensitive to anthrax. When even small doses of the microbe are administered subcutaneously, animals die within 2-4 days. At autopsy, anthrax bacilli are found in the blood and various organs.
Pathogenesis and clinic. The incubation period for anthrax lasts 2-3 days. There are several clinical forms of the disease depending on the method of infection: skin, pulmonary and intestinal. The most common (in 98% of cases) is the skin form of the disease. At the site where the anthrax bacilli invades, a red spot appears, which then turns into a papule, pustule, and, as the inflammatory process intensifies, into an anthrax carbuncle. Most often it is located on the face, hands and other open parts of the body.
The patient's general condition is serious: temperature 0°C, severe headache, enlarged regional lymph nodes. Usually the skin form, with timely treatment, ends in recovery. However, if the course is unfavorable, the pathogen can enter the blood, which leads to the development of sepsis and usually ends in death. The pulmonary form occurs only in humans and is characterized by high fever, the development of bronchopneumonia, severe shortness of breath and other symptoms. In the intestinal form, abdominal pain, bloating, and dyspepsia are observed. With pulmonary and intestinal forms, the prognosis is unfavorable - the disease ends in the death of the patient. In very rare cases, with massive infection with virulent strains of anthrax bacilli, a (primarily) septic form develops, leading to death.
Immunity. In case of anthrax, it is unstable, repeated diseases are possible. The main role in protecting the body belongs to the phagocytic reaction, caused by the formation of a protective antigen.
Microbiological diagnostics. Pathological material taken from the patient is sent to the laboratory: carbuncle discharge, sputum, feces, blood, material from animals (wool, skin, meat, cadaveric material, etc.), water, soil, swabs from various environmental objects. Laboratory diagnosis of anthrax consists of a microbiological study, a bioassay, a skin allergy test, and the Ascoli thermoprecipitation reaction.
During a microbiological examination, a smear is prepared from pathological material, stained with Gram, and examined under a microscope. Then the material is inoculated on meat-peptone agar and meat-peptone broth and grown for 24 hours in a thermostat at 37°C. The isolated culture is identified by morphological and cultural properties. To isolate a pure culture of anthrax bacilli, the test material can be injected subcutaneously into guinea pigs or white mice (bioassay). Animals usually die within 1-2 days. The characteristic pathological picture at autopsy and microscopy of smears from various organs (the presence of capsular anthrax bacilli) help make a diagnosis.
A skin allergy test is also used, which is positive from the first days of the disease. The method is based on the ability of the patient’s body to respond with a local allergic reaction to the introduction of an anthrax allergen (anthraxin).
In order to detect anthrax antigen in various objects (leather, fur raw materials, etc.), the thermoprecipitation reaction of Decal with precipitating anti-anthrax serum is used. This reaction is highly sensitive; a negative result excludes the presence of anthrax.
Prevention and treatment. Since the source of infection is animals, the main preventive measures are carried out by the veterinary service. Specific prevention is the introduction of live anthrax vaccine STI, obtained from a capsular strain of anthrax bacilli. Vaccination is carried out according to epidemiological indications to persons associated with livestock farming. Immunity after vaccination lasts up to a year.
For treatment, antibiotics, specific anti-anthrax serum and globulin are used.
anthrax (malignant carbuncle) - acute infectious disease of zoonotic origin, occurring predominantly in the form of a cutaneous form, pulmonary and intestinal forms are rarely observed, and is included in the group of especially dangerous infections.
anthrax in a susceptible organism, the vegetative form forms a capsule; in the environment, with access to free air oxygen and a temperature of 15-42 ° C, a spore located in the center of the spore rod is formed from the vegetative cells. The pathogenicity of the microbe is determined by the capsule (which has antiphagocytic activity and promotes fixation of the microbe on the host cells) and the heat-labile exotoxin, consisting of three components - edema (edematous), protective antigen (immunogen) and lethal factor.
Anthrax. Etiology.
The causative agent is a Gram-positive, immobile large Bacillus anihracis rod, 6-10 µm long and 1-2 µm wide, Gram stained, forms spores and a capsule, is an aerobe and a facultative anaerobe. Grows well on various nutrient media. In a susceptible organism, the vegetative form of the pathogen forms a capsule; in the environment, with access to free air oxygen and a temperature of 15-42 ° C, a spore located in the center of the spore stick is formed from the vegetative cells. Vegetative forms quickly die without access to air, when heated, under the influence of various disinfectants. The virulence of the pathogen is due to the presence of a capsule and exotoxin. In addition to penicillin, the causative agent of anthrax is also sensitive to antibiotics of the tetracycline group, chloramphenicol, streptomycin, and neomycin.
anthrax has various pathogenicity factors. Pathogenicity is determined by the capsule (which has antiphagocytic activity and promotes fixation of the microbe on the host cells) and a heat-labile exotoxin, consisting of three components - edematous (edematous), protective antigen (immunogen) and lethal factor.
Anthrax. Resistance.
anthrax in the vegetative form it is relatively little stable: at a temperature of 55°C they die after 40 minutes, at 60°C - after 15 minutes, when boiling - instantly. Vegetative forms are inactivated by standard disinfectant solutions after a few minutes. In unopened corpses they persist for up to 7 days.
anthrax has spores that are very stable in the external environment, they can persist in the soil for up to 10 years or more, and are formed outside the body with access to free oxygen. The spores are extremely stable: after 5-10 minutes of boiling, they all retain the ability to vegetate. Under the influence of dry heat at 120-140°C they die after 1-3 hours, in an autoclave at 110°C - after 40 minutes. A 1% formalin solution and a 10% sodium hydroxide solution kills spores in 2 hours. Temperature affects the survival time of spores environment, at which sporulation occurred. Spores formed at a temperature of 18-20°C are more stable.
Anthrax. Epidemiology.
anthrax has various sources of infection, for example, domestic animals (cattle, sheep, goats, camels, pigs). Infection can occur when caring for sick animals, slaughtering livestock, processing meat, as well as through contact with animal products (hides, skins, fur products, wool, bristles) contaminated with spores of the anthrax microbe. Infection is predominantly occupational in nature. Infection can occur through soil in which spores of the anthrax pathogen persist for many years. Spores enter the skin through microtraumas; in case of nutritional infection (consumption of contaminated products), an intestinal form occurs.
Among animals, the alimentary route of infection is of important epizootological importance - through food and water contaminated with anthrax spores; aerosol, vector-borne infection through milk and dairy products are of less importance. The pathogen can be transmitted by horseflies and burner flies, in whose mouthparts the pathogen can survive for up to 5 days.
anthrax can be transmitted aerogenously (inhalation of infected dust, bone meal). In these cases anthrax initiates pulmonary and generalized forms of infection. In African countries, the possibility of transmission of infection through the bites of blood-sucking insects is accepted. Human-to-human transmission is not usually observed. anthrax widespread in many countries in Asia, Africa and South America. In the USA and European countries anthrax It is extremely rare and isolated cases of disease are observed.
Anthrax. Pathogenesis.
The absence of infection between humans and humans is explained by the peculiarities of the transmission mechanism, which is realized among animals or from animals to humans and is impossible among humans due to the peculiarities of the first phase of isolation of the pathogen from the infected organism. In a sick animal, before death, the pathogen is released with various excreta; the blood from the corpse is saturated with anthrax bacilli, which leads to a high intensity of contamination of animal products. Spontaneous release of anthrax bacilli from a skin lesion in humans is not observed. Since rods are not found in the serous-hemorrhagic exudate of the carbuncle at the onset of the disease, instrumental intervention is required to isolate them from the blood. Anthrax bacilli are also absent in the discharge of a patient with a septic form of the disease.
anthrax most often penetrates through the skin. Typically, the pathogen invades the skin of the upper extremities (about half of all cases) and the head (20-30%), less often the torso (3-8%) and legs (1-2%). Mostly exposed areas of skin are affected. Within a few hours after infection, the pathogen begins to multiply at the site of infection (in the skin). In this case, pathogens form capsules and secrete exotoxin, which causes dense swelling and necrosis.
Capsule, which is a polypeptide, has antiphagocytic activity, prevents opsonization and phagocytosis of bacilli and at the same time promotes their fixation on host cells. anthrax due to this, it becomes invasive and can take root in the macroorganism, then multiply and develop bacteremia. anthrax It has strains that have a capsule; it distinguishes virulent anthrax strains from the vaccine strain.
Exotoxin inhibits the nonspecific bactericidal activity of humoral and cellular factors, phagocytosis, has anti-complementary activity, increases the virulence of anthrax bacilli, causes death in the terminal stage of the disease, inhibiting the function of the respiratory center and hypothalamus. Endogenous products of anthrax microbes do not have a pronounced toxic effect.
From the sites of primary reproduction, pathogens reach regional lymph nodes through lymphatic vessels, and subsequently hematogenous spread of microbes to various organs is possible. In the skin form at the site of the primary inflammatory-necrotic focus, secondary bacterial infection does not play a special role.
During aerogenic infection, the spores are phagocytosed by alveolar macrophages, then they enter the mediastinal lymph nodes, where the pathogen multiplies and accumulates; the mediastinal lymph nodes also become necrotic, which leads to hemorrhagic mediastenitis and bacteremia. As a result of bacteremia, secondary hemorrhagic anthrax pneumonia occurs.
When eating infected (and insufficiently heated) meat, the spores penetrate the submucosa and regional lymph nodes. An intestinal form of anthrax develops, in which the pathogens also penetrate the blood and the disease becomes septic. Thus, anthrax may have a septic course with any form of infection. In the pathogenesis of anthrax great importance has exposure to toxins produced by the pathogen.
Anthrax. Immunity.
The transferred disease leaves behind a strong immunity, although there are descriptions of repeated diseases 10-20 years after the first disease.
Anthrax. Symptoms and course.
anthrax There is an incubation period that ranges from several hours to 8 days (usually 2-3 days). anthrax It has various shapes, distinguish between skin, pulmonary (inhalation) and intestinal. The last two forms are characterized by hematogenous dissemination of microorganisms and are sometimes combined under the name of the generalized (septic) form, although these two forms differ from each other in changes in the area of the infection gate. Most often, the cutaneous form is observed (in 95%), rarely pulmonary and very rarely (less than 1%) intestinal.
Cutaneous form is divided into the following clinical varieties: carbunculous, edematous, bullous and erysipeloid [Nikiforov V.N., 1973]. The most common type is the carbunculous variety. The cutaneous form is characterized by local changes in the area of the infection gate. Initially, a red spot appears at the site of the lesion, which rises above the skin level, forming a papule, then a vesicle develops in place of the papule, after some time the vesicle turns into a pustule, and then into an ulcer. The process proceeds quickly, several hours pass from the moment the spot appears until the formation of the pustule.
Locally, patients note itching and burning. The contents of the pustule are often dark in color due to the admixture of blood. If the integrity of the pustule is violated (usually by scratching), an ulcer forms, which becomes covered with a dark crust. Around the central scab, secondary pustules are located in the form of a necklace, and when destroyed, the size of the ulcer increases. There is swelling and hyperemia of the skin around the ulcer, especially pronounced when the process is localized on the face. Characterized by a decrease or complete absence of sensitivity in the area of the ulcer.
Most often, the ulcer is localized on the upper extremities: fingers, hand, forearm, shoulder (498 cases out of 1329), followed by the forehead, temples, crown, cheekbone, cheek, eyelid, lower jaw, chin (486 patients), neck and back of the head (193 ), chest, collarbone, mammary glands, back, abdomen (67), the ulcer was localized on the lower extremities in only 29 people. Other localizations were rare.
Signs of general intoxication (fever up to 40°C, general weakness, fatigue, headache, adynamia, tachycardia) appear by the end of the first day or on the 2nd day of illness. The fever lasts for 5-7 days, body temperature drops critically. Local changes in the area of the ulcer gradually heal, and by the end of the 2-3rd week the scab is rejected. Usually there is a single ulcer, although sometimes there can be multiple ones (2-5 and even 36). An increase in the number of ulcers does not have a noticeable effect on the severity of the disease. The age of the patient has a greater influence on the severity of the disease. Before the introduction of antibiotics into practice, among patients over 50 years of age, mortality was 5 times higher (54%) than among younger people (8-11%). In those vaccinated against anthrax, skin changes may be very minor, resembling an ordinary boil, and general signs of intoxication may be absent.
The edematous variety of cutaneous anthrax is rare and is characterized by the development of edema without a visible carbuncle at the onset of the disease. The disease is more severe with pronounced manifestations of general intoxication. Later, in place of dense painless swelling, skin necrosis appears, which is covered with a scab.
anthrax has a bullous type of skin form, which is rarely observed. It is characterized by the fact that in place of a typical carbuncle in the area of the infection gate, blisters filled with hemorrhagic fluid form. They appear on an inflamed infiltrated base. The blisters reach large sizes and open only on the 5-10th day of illness. In their place, an extensive necrotic (ulcerative) surface is formed. This type of anthrax occurs with high fever and severe symptoms of general intoxication.
anthrax has an erysipeloid type of skin form, which is most rarely observed. Its peculiarity is the formation of a large number of whitish blisters filled with clear liquid, located on swollen, reddened, but painless skin. After opening the blisters, multiple ulcers remain that quickly dry out. This type is characterized by a milder course and a favorable outcome.
Pulmonary form anthrax begins acutely, progresses severely, and even with modern methods treatment may be fatal. In the midst of complete health, tremendous chills occur, body temperature quickly reaches high numbers (40°C and above), conjunctivitis is noted (lacrimation, photophobia, conjunctival hyperemia), catarrhal symptoms of the upper respiratory tract (sneezing, runny nose, hoarse voice, cough). From the first hours of illness, the condition of patients becomes severe, severe stabbing pain in the chest, shortness of breath, cyanosis, tachycardia (up to 120-140 beats/min) appear, blood pressure decreases. There is an admixture of blood in the sputum. Above the lungs, areas of dullness of percussion sound, dry and wet rales, and sometimes pleural friction noise are detected. Death occurs within 2-3 days.
Intestinal form Anthrax is characterized by general intoxication, increased body temperature, epigastric pain, diarrhea and vomiting. There may be blood in the vomit and stool. The abdomen is swollen, sharply painful on palpation, signs of peritoneal irritation are revealed. The patient's condition progressively worsens and with the phenomena of infectious-toxic shock, patients die.
With any of the described forms, anthrax sepsis can develop with bacteremia, the occurrence of secondary foci (meningitis, damage to the liver, kidneys, spleen and others).
Anthrax. Diagnosis and differential diagnosis.
anthrax is recognized on the basis of epidemiological history data (the patient’s profession, the nature of the material being processed, where the raw materials were delivered from, contact with sick animals, etc.). Characteristic changes in the skin in the area of the infection gate are also taken into account (location on open areas of the skin, the presence of a dark scab surrounded by secondary pustules, edema and hyperemia, anesthesia of the ulcer). It should be borne in mind that in vaccinated people, all skin changes may be mild and resemble staphylococcal diseases (furuncle and others).
anthrax is confirmed by laboratory methods and is carried out through the isolation of an anthrax bacillus culture and its identification. For research, the contents of pustules, vesicles, and tissue effusion from under the scab are taken. If a pulmonary form is suspected, blood, sputum, and stool are collected. In cutaneous forms, blood cultures are rarely isolated. The collection and transfer of material is carried out in compliance with all rules for working with especially dangerous infections.
To study material (skins, wool), the thermoprecipitation reaction (Accol reaction) is used. The immunofluorescent method is also used to detect the pathogen. As helper method You can use a skin allergy test with a specific allergen - anthraxin. The drug is administered intradermally (0.1 ml). The result is taken into account after 24 and 48 hours. The reaction is considered positive in the presence of hyperemia and infiltrate over 10 mm in diameter, provided that the reaction has not disappeared after 48 hours.
It is necessary to differentiate from a boil, carbuncle, erysipelas, in particular from the bullous form. The pulmonary (inhalational) form of anthrax is differentiated from the pulmonary form of plague, tularemia, melioidosis, legionellosis and severe pneumonia of other etiologies.
Anthrax. Treatment.
anthrax It is quite difficult to treat; antibiotics, as well as specific immunoglobulin, are used for etiotropic treatment. Most often, penicillin is prescribed for the cutaneous form, 2 million–4 million units/day parenterally. After the swelling in the area of the ulcer disappears, penicillin preparations can be prescribed orally (ampicillin, oxacillin for another 7-10 days).
For pulmonary and septic forms, penicillin is administered intravenously at a dose of 16-20 million units/day; for anthrax meningitis, such doses of penicillin are combined with 300-400 mg of hydrocortisone. If penicillin is intolerant to cutaneous anthrax, tetracycline is prescribed at a dose of 0.5 g 4 times a day for 7-10 days. You can also use erythromycin (0.5 g 4 times a day for 7-10 days). Recently, ciprofloxacin 400 mg every 8-12 hours, as well as doxycycline 200 mg 4 times a day, and then 100 mg 4 times a day have been recommended.
Specific anti-anthrax immunoglobulin is administered intramuscularly at a dose of 20-80 ml/day (depending on the clinical form and severity of the disease) after preliminary desensitization. First, to test sensitivity to horse protein, 0.1 ml of immunoglobulin, diluted 100 times, is injected intradermally. If the test is negative, 0.1 ml of diluted (1:10) immunoglobulin is administered subcutaneously after 20 minutes and the entire dose is administered intramuscularly after 1 hour. If there is a positive intradermal reaction, it is better to refrain from administering immunoglobulin.
Anthrax. Forecast.
Before the introduction of antibiotics into practice, the mortality rate for the cutaneous form reached 20%; with modern early antibiotic treatment, it does not exceed 1%. With pulmonary, intestinal and septic forms the prognosis is unfavorable.
Anthrax. Prevention, control measures and activities in the outbreak.
Veterinary activities are:
1. Identification, registration, certification of points unfavorable for anthrax.
2. Routine immunization of farm animals in disadvantaged areas.
3. Control over the implementation of reclamation and agrotechnical measures aimed at improving the health of disadvantaged territories and reservoirs.
4. Monitoring the proper condition of cattle burial grounds, cattle routes, pastures, and livestock breeding facilities.
5. Monitoring compliance with veterinary and sanitary rules during the procurement, storage, transportation and processing of raw materials.
6. Timely diagnosis of anthrax in animals, their isolation and treatment.
7. Epizootological examination of the epizootic outbreak, neutralization of the corpses of dead animals, current and final disinfection in the outbreak.
8. Veterinary and sanitary educational work among the population.
9. Preventive measures against anthrax include medical, sanitary and veterinary measures.
Medical and sanitary measures are:
1. Control over the implementation of general sanitary preventive measures in areas unaffected by anthrax, during the procurement, storage, transportation and processing of raw materials of animal origin.
2. Vaccinal prevention of persons at increased risk of anthrax infection (according to indications).
3. Timely diagnosis of anthrax disease in people, hospitalization and treatment of patients, epidemiological examination of the outbreak and final disinfection in the room where the sick person was.
4. Emergency prevention among persons who have come into contact with the source of the infectious agent or contaminated products.
5. Sanitary educational work among the population.
Anthrax. Vaccine prevention.
Persons who work with live cultures of the pathogen, infected laboratory animals, examine material infected with the causative agent of anthrax, veterinary workers and other persons professionally engaged in pre-slaughter livestock maintenance, slaughter, cutting of carcasses and skinning, as well as those engaged in collection, storage, transportation are subject to vaccination. and primary processing of raw materials of animal origin. Vaccination is carried out with live anthrax vaccine STI twice with an interval of 21 days. Revaccination is carried out annually at intervals of no more than a year in order to catch it before the seasonal rise in incidence.
Anthrax. Laboratory diagnostics.
Laboratory diagnosis is based on bacteriological examination of the contents of skin lesions, and if a generalized form is suspected, on examination of blood, sputum, and feces (early use of antibiotics sharply reduces the inoculability of the pathogen). A skin allergy test with anthraxin is performed, which is positive in 90% of cases in the first week of the disease. A positive test result is not taken into account in persons previously vaccinated against anthrax, if the period from the date of vaccination does not exceed 12 months. Laboratory studies are carried out in compliance with the regime required when working with pathogens of particularly dangerous infections.