Anthrax (charcoal). Gram-positive spore-forming bacteria Characteristics of the causative agent of anthrax microbiology

No. 16 The causative agent of anthrax. Taxonomy and characteristics. Microbiological diagnostics. Specific prevention and treatment.
Anthrax is an acute anthroponotic infectious disease caused by Bacillus anthracis, characterized by severe intoxication, damage to the skin and lymph nodes.
Taxonomy. The pathogen belongs to the division Firmicutes, genus Bacillus.
Morphological properties. Very large gram-positive rods with chopped ends, in a smear from a pure culture, are arranged in short chains (streptobacilli). motionless; form centrally located spores as well as a capsule.
Cultural properties. Aerobes. They grow well on simple nutrient media in the temperature range of 10-40C, the optimum growth temperature is 35C. On liquid media they produce bottom growth; on dense media they form large, rough, matte colonies with uneven edges (R-form). On media containing penicillin, after 3 hours of growth, anthrax bacilli form spheroplasts arranged in a chain and resembling a pearl necklace in a smear.
Biochemical properties. Enzymatic activity is quite high: pathogens ferment glucose, sucrose, maltose, starch, and inulin to acid; have proteolytic and lipolytic activity. They secrete gelatinase and have weak hemolytic, lecithinase and phosphatase activity.
They secrete gelatinase and exhibit low hemolytic, lecithinase and phosphatase activity.
Antigens and pathogenicity factors. Contain generic somatic polysaccharide and specific protein capsular antigens. They form a protein exotoxin that has antigenic properties and consists of several components (lethal, protective and causing edema). Virulent strains in a susceptible organism synthesize a complex exotoxin and a large amount of capsular substance with pronounced antiphagocytic activity.
Resistance. The vegetative form is unstable to environmental factors; the spores are extremely stable and persist in the environment and can withstand boiling. Sensitive to penicillin and other antibiotics; spores are resistant to antiseptics.
Epidemiology and pathogenesis. The source of infection is sick animals, most often cattle, sheep, and pigs. A person becomes infected mainly through contact, less often through nutrition, when caring for sick animals, processing animal raw materials, and eating meat. The entry point for infection in most cases is damaged skin, much less often the mucous membranes of the respiratory tract and gastrointestinal tract. The pathogenesis is based on the action of an exotoxin, which causes coagulation of proteins, tissue swelling, and lead to the development of toxic-infectious shock.
Clinic. There are cutaneous, pulmonary and intestinal forms of anthrax. In the cutaneous (localized) form, a characteristic anthrax carbuncle appears at the site of pathogen penetration, accompanied by swelling. Pulmonary and intestinal forms are generalized forms and are expressed by hemorrhagic and necrotic damage to the corresponding organs.
Immunity. After an illness, stable cellular-humoral immunity develops.
Microbiological diagnostics :
The most reliable method of laboratory diagnosis of anthrax is the isolation of a culture of the pathogen from the test material. The Ascoli thermoprecipitation reaction and the allergic skin test are also of diagnostic value.
Bacterioscopic examination. The study of Gram-stained smears from pathological material allows us to detect the pathogen, which is a large Gram-positive, non-motile streptobacilli. In the body of patients and on a protein nutrient medium, microorganisms form a capsule, in the soil - spores.
Bacteriological research. The test material is inoculated onto nutrient and blood agar plates, as well as into a test tube with nutrient broth. The crops are incubated at 37C for 18 hours. In broth, B. anthracis grows as a flocculent sediment; on agar, virulent strains form R-form colonies. Avirulent or weakly virulent bacteria form S-form colonies.
B. anthracis has saccharolytic properties, does not hemolyze red blood cells, and slowly liquefies gelatin. Under the influence of penicillin, it forms spheroplasts that look like “pearls”. This phenomenon is used to differentiate B. anthracis from non-pathogenic bacilli.
Bioassay . The test material is injected subcutaneously into guinea pigs and rabbits. Smears are prepared from blood and internal organs, and cultures are done to isolate a pure culture of the pathogen.
Express diagnostics carried out using the Ascoli thermoprecipitation reaction and the immunofluorescence method.
The Ascoli reaction is used when it is necessary to diagnose anthrax in dead animals or dead people. Samples of the test material are crushed and boiled in a test tube with an isotonic sodium chloride solution for 10 minutes, after which they are filtered until completely transparent.
The immunofluorescence method makes it possible to detect capsular forms of B. anthracis in the exudate. Smears from the exudate 5-18 hours after infection of the animal are treated with capsular anthrax antiserum, and then with fluorescent anti-rabbit serum. In preparations containing capsular bacilli, a yellow-green glow of the pathogen is observed.
Skin allergy test. Placed on the inner surface of the forearm - 0.1 ml of anthraxin is injected intradermally. If the reaction is positive, hyperemia and infiltration appear after 24 hours.
Treatment: antibiotics and anthrax immunoglobulin. For antibacterial therapy, the drug of choice is penicillin.
Prevention. For specific prevention, live anthrax vaccine is used. For emergency prevention, anthrax immunoglobulin is prescribed.
Precipitating anthrax serum. Obtained from the blood of a rabbit hyperimmunized with a culture of B. anthracis. It is used to perform the Ascoli thermoprecipitation reaction.
Anthrax live vaccine STI. A dried suspension of living spores of B. anthracis of an avirulent noncapsular strain. Used to prevent anthrax.
Anti-anthrax immunoglobulin. The gamma globulin fraction of the blood serum of a horse hyperimmunized with live anthrax vaccine and a virulent strain of B. anthracis is used for preventive and therapeutic purposes.

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 a 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 ear incision 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 connective tissue are sent from pig corpses for laboratory testing. 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 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 a 25% aqueous ammonia solution is applied to the inner surface of the lid of the Petri dish, and the dish is turned 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 * Siberia ulcerative 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 use Young animals of all types 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 there were animals sick or dead 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 IN ANTHRAX To disinfect surfaces contaminated with the pathogen, use: 10% hot solution of caustic soda, 4% solution of formaldehyde, solutions of bleach, two-thirds salt and neutral calcium hypochloride, DP - 2, hexanite with 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 % solution of glutaraldehyde. 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 registered 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 the Voronezh region in the first quarter (one animal fell ill); - for 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 (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 is an acute, particularly dangerous zoonotic infection. The diseases are predominantly of animals, among which the most susceptible are cattle, sheep, goats, deer, and horses. The name of the disease was proposed by S.S. Andreevsky in connection with the place where he studied it. There was a big epidemic in 1786-1788 in the Urals.

Anthrax bacilli were first discovered in the blood of sick animals in 1840. Pollender's discovery was confirmed in 1850.

In 1875, R. Koch was the first to isolate a pure culture of anthrax and finally establish the role of this microbe in the etiology of the disease. Working simultaneously with R. Koch, L. Pasteur in 1881 received similar data and, having studied the biology of the microbe, developed a method for preparing a live anthrax vaccine to prevent this disease. In 1883, L.S. Tsenkovsky received a highly effective vaccine, which was used in our country for 60 years to prevent anthrax disease among farm animals.

Taxonomy of the pathogen

• Class Shizomycetes
• Order Eeubacteriales
• Family Bacillaceae
• Species Bacillus Anthracis

Morphology of the pathogen

The causative agent of anthrax is a large rod, 5-10 microns long, 1-2 microns wide, immobile, gram-positive. In liquid masks, the bacillus is located in pairs or long chains. The ends of the bacilli in stained smears appear chopped off. Bacilli outside the body under unfavorable living conditions form spores, which are located in the center of the cell, have an oval shape and do not exceed the diameter of the body of the microbe, and do not deform it. Bacilli in the body of humans and animals form capsules surrounding both individual individuals and chains. Capsules are formed in special nutrient media containing blood, serum, egg white or brain tissue. The capsule consists of proteins.

In 1911 and 1912. In the Siberian region, the incidence of anthrax in animals per 100,000 livestock was 2000 and 1671, respectively; in 1908, in the Syrdarya region, anthrax was registered in 50 horses and 67 heads of cattle.

Toxin formation

• The bacillus secretes an exotoxin consisting of 3 factors:
• Inflammatory or edematous.
• Immunogenic.
• Lethal.

Anthrax toxin plays an important role in the pathogenesis and pathological physiology of anthrax infection, and such is involved in the formation of specific immunity.

Antigenic structure

Bacillus contains:

• O - Somatic antigen consisting of polysoccharides
• K - Capsular - thermolabel antigen.

In the body of animals and in special media containing tissue or plasma extracts, a special kind of antigen is produced that has high immunizing properties.

Resistance

Anthrax bacillus spores are highly resistant; dry steam kills them at a temperature of 140 C for 2-3 hours, and in an autoclave at 120 C they die after 13-20 minutes when boiled for 60 minutes. The vegetative form of the anthrax pathogen dies when heated to 55C for 40 minutes, 60C for 15 minutes, 75C for 1 minute. Direct sunlight and disinfectants easily kill the wand. The vegetative form exhibits resistance to low temperatures -1 °C.

Pathogenicity for animals

All types of herbivores are susceptible to the causative agent of anthrax; among domestic animals, cows, sheep, horses, pigs, and camels are susceptible. Animals develop weakness, cyanosis, and bloody discharge from the intestines, mouth and nose. Death occurs within 2-3 days.

Clinical disease in humans and pathogenesis

The incubation period lasts from several hours to 6-8 days, usually 2-3 days. The following forms are distinguished:

• Skin form.
• Pulmonary form.
• Intestinal form.
• Septic form.

In the human cutaneous form, anthrax carbuncle appears.

At the site of penetration of the pathogen, reddish spots initially appear, turning into a copper-red capsule. After a few hours, the capsule turns into an itchy blister. Characteristically, there is no pain in the area of ​​surrounding swelling.

The pulmonary form is rare and occurs as bronchopneumonia. Death due to the development of sepsis.

The intestinal form is rare and occurs in the form of general intoxication with catarrhal hemorrhagic phenomena of the digestive system. The patient experiences nausea, vomiting, and bloody diarrhea.

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Anthrax bacillus - you. anthracis (Fig. 96) belongs to the group of gram-positive aerobic spore-forming bacilli, widespread in nature. Anthrax bacillus is the only pathogenic representative of this group.
Anthrax bacilli were first discovered in the blood of animals by the German scientist A. Pallender in 1839. The same microorganisms were observed in the blood of animals in France in 1850 by C. Daven. However, the true significance of these microbes in the etiology of the Siberian disease was established in Russia by Prof. F.A. Brauel in 1855. R. Koch, with his classical studies on anthrax, finally proved the bacterial nature of Pallender and Daven bacilli, established their ability to form spores, obtained a pure culture and successfully infected experimental animals with it.
Morphology and tinctorial properties. Anthrax bacilli are large, thick rods, 1-2 microns wide and 8 microns long. They are located mainly in pairs or chains. The ends of the sticks on the colored preparations are motionless and appear as if they were chopped off.

Rice. 96. Anthrax bacillus.
1 - colonies on agar; 2 - anthrax bacilli in pure culture; 3 - growth when sowing by injection into gelatin.
A morphological feature of anthrax bacilli is their ability to form spores and capsules (Fig. 97 and 98 inset).

Rice. 97. Anthrax bacillus spores. Hansen staining.

The spores are located centrally, oval in shape; their diameter does not exceed the diameter of the microbial cell. Spores are formed outside the body with a sufficient supply of oxygen; capsules, on the contrary, are formed in the body and are lost when the bacilli are cultivated on nutrient media. Anthrax bacilli stain well with aniline dyes and are gram-positive.
Cultural and biochemical properties. Anthrax bacillus grows well on all nutrient media, aerobic. Temperature optimum 37°
Quite large, rough colonies, matte with a fringed periphery, grow on agar plates. These are virulent R colonies.
At low microscope magnification, colonies have a fibrous structure, and the fibers are collected in the form of curls of hair, which is why they are compared to a lion’s mane or a jellyfish’s head.
Less common are smooth colonies with smooth edges (S-colonies), containing weakly virulent or avirulent forms of bacilli.
After 24 hours of growth, the agar slant develops a grayish-white coating with curls around the edges. Growth in broth is typical: the medium remains transparent, and at the bottom there is a sediment resembling a lump of cotton wool. The gelatin slowly liquefies and resembles a Christmas tree with its top turned down. The milk curdles on the 3-4th day of growth, then the casein is peptonized. The potatoes get a dry, grayish-white coating. The microbe is saccharolytic: it decomposes glucose, maltose, lactose with the formation of acid (without gas), but does not have hemolytic properties.
Antigenic structure. Anthrax bacillus has specific antigens: somatic polysaccharide and protein, located in the capsule. The polysaccharide antigen is heat-stable and persists for a long time in animal corpses and skins. Extracted from them by boiling, it gives a positive precipitation reaction with type-specific serum.
Resistance. Vegetative forms of anthrax bacilli are poorly resistant, while spores are highly resistant. They can withstand boiling for up to 5-10 minutes, direct sunlight for 100 hours. When dried, the spores can remain viable for up to 20 years. Very resistant to disinfectants. In 15% chlorine water they remain viable for 6 hours, in 4% hydrochloric acid for 15 days, in a 5% solution of sublimate for 15 days. For disinfection of anthrax, the following are used: dry bleach, bleach-lime milk, clarified solutions of this milk, activated solutions of chloramine, hot solutions of caustic soda.
Toxin formation and pathogenicity for animals.
The issue of toxins from anthrax bacilli is still unclear. Attempts to obtain the toxin in. vitro were unsuccessful: neither exo- nor endotoxin could be detected. The introduction of filtrates of broth cultures or killed microbial bodies to sensitive animals has almost no toxic effect.
Cattle and small ruminants are especially susceptible to anthrax, and horses are somewhat less susceptible. Pigs get it much less often. Cats and dogs are immune to anthrax. Of the laboratory animals, white mice and guinea pigs are the most sensitive to anthrax. Subcutaneous injection of a small amount of virulent bacilli causes the death of the animal within 2-4 days.
Pathogenesis and clinic. The source of infection is sick animals (cattle and small cattle, horses) and the products and raw materials obtained from them. In humans, this disease is rare and is most often associated with a certain profession. Infection occurs as a result of direct contact with sick animals (shepherds, slaughterhouse workers, etc.) or through contact with contaminated products of animal origin (tanners, furriers, wool beaters). The pulmonary form occurs in workers involved in processing contaminated rags (“rag pickers’ disease”). Infection occurs through the skin, mucous membrane of the upper respiratory tract and intestines; depending on the location of the entrance gate, anthrax in humans manifests itself in three forms: cutaneous, pulmonary and intestinal. The most common form is cutaneous, less commonly pulmonary and very rarely intestinal.

Rice. 98. Capsules of the anthrax bacillus. Fuchsin staining.

The incubation period lasts 1-3 days.
The cutaneous form is expressed in the form of a so-called malignant pustule (anthrax carbuncle - Pustula maligna). First, a red spot appears, which quickly turns into a papule (nodule), and then into a vesicle filled with bloody fluid. The center of the vesicle becomes necrotic and turns black, which is characteristic of anthrax carbuncle. The black color of the anthrax carbuncle was the reason to call it coal (anthrax - coal).
The necrotic central area of ​​the carbuncle is often surrounded by a necklace of small bubbles. The tissue around the carbuncle swells, the nearest lymph nodes enlarge.
The disease is accompanied by a rise in temperature to 40°, severe general symptoms, weakness of cardiac activity, confusion, and the ulcer itself
Smears are made from pathological material and stained with Gram stain. The detection in smears of characteristic large gram-positive rods surrounded by capsules, with the tendency of microbes to be arranged in chains, makes it possible to make a preliminary diagnosis. However, in order to make a completely accurate diagnosis, bacterioscopic examination alone is not enough. Therefore, it is necessary to identify another pure culture of you. anthracis. For this purpose, the test material is inoculated onto plates with regular agar and into test tubes with broth. After 20-24 hours of cultivation, typical colonies are examined, which, under low microscope magnification, appear in the form of intertwined threads. The colonies are sown on agar slants and then the isolated pure culture is examined.
The obtained data of bacteriological research are confirmed by infection of animals. The isolated culture is injected subcutaneously into a white mouse or guinea pig, and if the culture consists of anthrax bacilli, the animal dies within 24-48 hours with a picture of acute sepsis.
If sepsis is suspected, blood cultures are performed. If in the material under study (skin, wool, etc.) bacilli or their spores cannot be detected bacterioscopically and bacteriologically, they resort to serological research using the Ascoli thermoprecipitation reaction. The following ingredients are required to carry out the reaction.

1. precipitating anthrax serum;
2. normal serum of the animal from which the precipitating serum was obtained;
3. anthrax standard antigen for control (prepared at the institutes of vaccines and serums);
4. antigen from the material to be tested.

Most often, pieces of organs, wool, skin, etc. are taken for thermoprecipitation. The specified material is poured with 5-10 times the volume of physiological solution and boiled in a water bath (at low heat) for 10-20 minutes, and then filtered through a paper filter until complete transparency.
A positive result of the reaction is the immediate (sometimes after 5-10 minutes) appearance of a ring-shaped precipitate at the interface between the liquids. The appearance of a ring after 10 minutes is considered a nonspecific or questionable reaction.
Prevention and therapy. Specific prevention of anthrax has been widely used since the time of L. Pasteur by vaccinating animals with asporogenous cultures of the anthrax bacillus. Two vaccines are used, which are obtained by growing the bacillus at a temperature of 42-43° for 24 (the first vaccine) and 12 (the second vaccine) days.
Until recently, the Soviet Union used the Tsenkovsky vaccine, which is prepared according to Pasteur’s principle, but is safer.
In recent years, a new non-capsule vaccine, STI (Sanitary Technical Institute), has been widely used, which is highly effective and safe.
For therapeutic purposes, patients are administered intravenously or intramuscularly with immune anti-anthrax serum in an amount of 50-100 ml.
In addition to serum, novarsenol 0.45-0.6 g intravenously is also used for anthrax. In terms of its therapeutic effect, this drug is inferior to serum. Penicillin gives a positive result when administered at a dose of 300,000-400,000 units per day until a lasting effect is obtained.

anthrax (malignant carbuncle) is an acute infectious disease of zoonotic origin, occurring mainly 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 - edematous (edematous), protective antigen (immunogen) and lethal factor.

Anthrax. Etiology.

The causative agent is a gram-positive, immobile large rod of Bacillus anihracis, 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 rod 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. The survival time of spores is affected by the ambient temperature 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, exposure to toxins produced by the pathogen is of great importance.

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 has various forms, distinguished 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, is severe, and even with modern treatment methods can 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 an auxiliary 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 especially dangerous infections.