Anaerobes and aerobes. Anaerobic microorganisms No growth of aerobic or anaerobic bacteria

Cell membrane bacteria are permeable: through it nutrients freely pass into the cell, and metabolic products exit into the environment. Cell wall- is inherent in most bacteria (except for mycoplasmas, acholeplasmas and some other microorganisms that do not have a true cell wall). It has a number of functions, primarily providing mechanical protection and a constant shape of cells; the antigenic properties of bacteria are largely associated with its presence. The cell wall of bacteria is a fairly strong structure and allows the cell to maintain its shape; this is due to the presence in it mureina- a molecule constructed from parallel polysaccharide chains cross-linked at regular intervals by short chains of amino acids.

Often, bacteria produce an additional protective layer of mucus on top of the cell wall - a capsule.

Capsule protects the bacteria from drying out. The capsule contains toxins. The thickness of the capsule can be many times greater than the diameter of the cell itself, but it can also be very small.

On the surface of some bacteria there are long flagella(one, two or many) or short thin fibers. The length of the flagella can be many times greater than the size of the bacterial body. Bacteria move with the help of flagella and villi.

The cytoplasmic membrane regulates the flow of nutrients into the cell and the release of metabolic products to the outside, and takes part in cell metabolism. It has a typical structure: a bimolecular layer of phospholipids with built-in proteins. Membrane proteins are mainly represented by structural proteins with enzymatic activity. Typically, the growth rate of the cytoplasmic membrane is faster than the growth rate of the cell wall. This leads to the fact that the membrane often forms numerous invaginations (invaginations) of various shapes - mesosomes(participate in energy metabolism, sporulation, formation of intercellular partition during division)

The cells of photosynthetic bacteria contain intracytoplasmic membrane formations - chromatophores, which ensure the occurrence of bacterial photosynthesis.

Unlike other single-celled organisms, bacteria do not have a nucleus: their nuclear substance is not separated from the cytoplasm by a membrane and is distributed in the cytoplasm.

Nucleoid. The DNA molecule has a typical structure. It consists of two polynucleotide chains forming a double helix. Unlike eukaryotes, DNA has a circular structure rather than a linear structure. The DNA molecule of bacteria is identified with one chromosome of eukaryotes. But if in eukaryotes DNA is associated with proteins in the chromosomes, then in bacteria DNA does not form complexes with proteins.

Bacterial DNA is anchored on the cytoplasmic membrane in the mesosome region.

The cells of many bacteria have non-chromosomal genetic elements - plasmids. They are small circular DNA molecules that can replicate independently of chromosomal DNA. Among them there is the F-factor, a plasmid that controls the sexual process. (see also biotechnology, insulin production)

Ribosomes. Smaller in size than eukaryotic ribosomes, protein synthesis occurs in them. Ribosomes lie freely in the cytoplasm and are not associated with membranes (as in eukaryotes). Bacteria are characterized by 70S ribosomes, formed by two subunits: 30S and 50S. Ribosomes of bacterial cells are assembled into polysomes formed by dozens of ribosomes.

Anaerobes and aerobes are two forms of existence of organisms on earth. The article deals with microorganisms.

Anaerobes are microorganisms that develop and multiply in an environment that does not contain free oxygen. Anaerobic microorganisms are found in almost all human tissues from purulent-inflammatory foci. They are classified as opportunistic (they exist in humans and develop only in people with a weakened immune system), but sometimes they can be pathogenic (disease-causing).

There are facultative and obligate anaerobes. Facultative anaerobes can develop and reproduce in both anoxic and oxygenic environments. These are microorganisms such as Escherichia coli, Yersinia, staphylococci, streptococci, Shigella and other bacteria. Obligate anaerobes can only exist in an oxygen-free environment and die when free oxygen appears in the environment. Obligate anaerobes are divided into two groups:

• bacteria that form spores, otherwise called clostridia
• bacteria that do not form spores, or otherwise non-clostridial anaerobes.

Clostridia are causative agents of anaerobic clostridial infections - botulism, clostridial wound infections, tetanus. Non-clostridial anaerobes are the normal microflora of humans and animals. These include rod-shaped and spherical bacteria: bacteroides, fusobacteria, peillonella, peptococci, peptostreptococci, propionibacteria, eubacteria and others.

But non-clostridial anaerobes can significantly contribute to the development of purulent-inflammatory processes (peritonitis, abscesses of the lungs and brain, pneumonia, pleural empyema, phlegmon of the maxillofacial area, sepsis, otitis media and others). Most anaerobic infections caused by non-clostridial anaerobes are endogenous (internal origin, caused by internal causes) and develop mainly with a decrease in the body's resistance, resistance to the effects of pathogens as a result of injuries, operations, hypothermia, and decreased immunity.

The main part of anaerobes that play a role in the development of infections are bacteroides, fusobacteria, peptostreptococci and spore bacilli. Half of purulent-inflammatory anaerobic infections are caused by bacteroides.

• Bacteroides are rods, 1-15 microns in size, motile or moving with the help of flagella. They secrete toxins that act as virulence (disease-causing) factors.
• Fusobacteria are rod-shaped obligate (surviving only in the absence of oxygen) anaerobic bacteria that live on the mucous membrane of the mouth and intestines, can be immobile or motile, and contain a strong endotoxin.
• Peptostreptococci are spherical bacteria, located in twos, fours, irregular clusters or chains. These are flagellate bacteria and do not form spores. Peptococci are a genus of spherical bacteria represented by one species, P. niger. Located singly, in pairs or in clusters. Peptococci do not have flagella and do not form spores.
• Veyonella is a genus of diplococci (coccal-shaped bacteria, the cells of which are arranged in pairs), arranged in short chains, immobile, and do not form spores.
• Other non-clostridial anaerobic bacteria that are isolated from infectious foci of patients are propionic bacteria, volinella, the role of which is less studied.

Clostridia is a genus of spore-forming anaerobic bacteria. Clostridia live on the mucous membranes of the gastrointestinal tract. Clostridia are mainly pathogenic (disease-causing) to humans. They secrete highly active toxins specific to each species. The causative agent of an anaerobic infection can be either one type of bacteria or several types of microorganisms: anaerobic-anaerobic (bacteroides and fusobacteria), anaerobic-aerobic (bacteroides and staphylococci, clostridia and staphylococci)

Aerobes are organisms that require free oxygen to survive and reproduce. Unlike anaerobes, aerobes have oxygen involved in the process of producing the energy they need. Aerobes include animals, plants and a significant part of microorganisms, among which are isolated.

• obligate aerobes are “strict” or “unconditional” aerobes that receive energy only from oxidative reactions involving oxygen; these include, for example, some types of pseudomonads, many saprophytes, fungi, Diplococcus pneumoniae, diphtheria bacilli
• In the group of obligate aerobes, microaerophiles can be distinguished - they require a low oxygen content to function. When released into the normal external environment, such microorganisms are suppressed or die, since oxygen negatively affects the action of their enzymes. These include, for example, meningococci, streptococci, gonococci.
• facultative aerobes are microorganisms that can develop in the absence of oxygen, for example, yeast bacillus. Most pathogenic microbes belong to this group.

For each aerobic microorganism there is a minimum, optimum and maximum oxygen concentration in its environment necessary for its normal development. An increase in oxygen content beyond the “maximum” limit leads to the death of microbes. All microorganisms die at an oxygen concentration of 40-50%.

Bacteria are present everywhere in our world. They are everywhere, and the number of their varieties is simply amazing.

Depending on the need for oxygen in the nutrient medium to carry out life activities, microorganisms are classified into the following types.

• Obligate aerobic bacteria, which gather in the upper part of the nutrient medium, contained the maximum amount of oxygen in the flora.
• Obligate anaerobic bacteria, which are found in the lower part of the environment, are as far away from oxygen as possible.
• Facultative bacteria mainly live in the upper part, but can be distributed throughout the environment, since they do not depend on oxygen.
• Microaerophiles prefer low concentrations of oxygen, although they accumulate in the upper part of the medium.
• Aerotolerant anaerobes are evenly distributed in the nutrient medium and are insensitive to the presence or absence of oxygen.

The concept of anaerobic bacteria and their classification

The term "anaerobes" appeared in 1861, thanks to the work of Louis Pasteur.

Anaerobic bacteria are microorganisms that develop regardless of the presence of oxygen in the nutrient medium. They get energy by substrate phosphorylation. There are facultative and obligate aerobes, as well as other species.

The most significant anaerobes are bacteroides

The most significant aerobes are bacteroides. Approximately fifty percent of all purulent-inflammatory processes, the causative agents of which can be anaerobic bacteria, account for bacteroides.

Bacteroides are a genus of gram-negative obligate anaerobic bacteria. These are rods with bipolar stainability, the size of which does not exceed 0.5-1.5 by 15 microns. Produce toxins and enzymes that can cause virulence. Different bacteroides have different resistance to antibiotics: both resistant and sensitive to antibiotics are found.

Energy production in human tissues

Some tissues of living organisms have increased resistance to low oxygen levels. Under standard conditions, adenosine triphosphate synthesis occurs aerobically, but with increased physical activity and inflammatory reactions, the anaerobic mechanism comes to the fore.

Adenosine triphosphate (ATP) is an acid that plays an important role in the body's production of energy. There are several options for the synthesis of this substance: one aerobic and three anaerobic.

Anaerobic mechanisms for ATP synthesis include:

• rephosphorylation between creatine phosphate and ADP;
• transphosphorylation reaction of two ADP molecules;
• anaerobic breakdown of blood glucose or glycogen reserves.

Cultivation of anaerobic organisms

There are special methods for growing anaerobes. They consist of replacing air with gas mixtures in sealed thermostats.

Another way would be to grow microorganisms in a nutrient medium to which reducing substances are added.

Nutrient media for anaerobic organisms

There are common culture media and differential diagnostic nutrient media. Common ones include the Wilson-Blair environment and the Kitt-Tarozzi environment. Differential diagnostic ones include Hiss's medium, Ressel's medium, Endo's medium, Ploskirev's medium and bismuth-sulfite agar.

The base for Wilson-Blair medium is agar-agar with the addition of glucose, sodium sulfite and ferrous chloride. Black colonies of anaerobes form mainly in the depths of the agar column.

Russell's medium is used to study the biochemical properties of bacteria such as Shigella and Salmonella. It also contains agar-agar and glucose.

Wednesday Ploskireva inhibits the growth of many microorganisms, so it is used for differential diagnostic purposes. In such an environment, pathogens of typhoid fever, dysentery and other pathogenic bacteria develop well.

The main purpose of bismuth sulfite agar is to isolate salmonella in its pure form. This environment is based on the ability of Salmonella to produce hydrogen sulfide. This environment is similar to the Wilson-Blair environment in terms of the methodology used.

Anaerobic infections

Most anaerobic bacteria living in the human or animal body can cause various infections. As a rule, infection occurs during a period of weakened immunity or disruption of the general microflora of the body. There is also the possibility of pathogens entering from the external environment, especially in late autumn and winter.

Infections caused by anaerobic bacteria are usually associated with the flora of human mucous membranes, that is, with the main habitats of anaerobes. Typically, such infections several pathogens at once(to 10).

The exact number of diseases caused by anaerobes is almost impossible to determine due to the difficulty of collecting materials for analysis, transporting samples and cultivating the bacteria themselves. Most often, this type of bacteria is found in chronic diseases.

People of any age are susceptible to anaerobic infections. At the same time, children have a higher rate of infectious diseases.

Anaerobic bacteria can cause various intracranial diseases (meningitis, abscesses and others). Spread usually occurs through the bloodstream. In chronic diseases, anaerobes can cause pathologies in the head and neck area: otitis, lymphadenitis, abscesses. These bacteria pose a danger to both the gastrointestinal tract and lungs. With various diseases of the female genitourinary system, there is also a risk of developing anaerobic infections. Various diseases of the joints and skin can be a consequence of the development of anaerobic bacteria.

Causes of anaerobic infections and their signs

All processes during which active anaerobic bacteria enter tissues lead to infections. Also, the development of infections can be caused by impaired blood supply and tissue necrosis (various injuries, tumors, edema, vascular diseases). Oral infections, animal bites, pulmonary diseases, pelvic inflammatory disease and many other diseases can also be caused by anaerobes.

The infection develops differently in different organisms. This is influenced by both the type of pathogen and the state of human health. Because of the difficulties associated with diagnosing anaerobic infections, the conclusion is often based on guesswork. Infections caused by non-clostridial anaerobes.

The first signs of tissue infection by aerobes are suppuration, thrombophlebitis, and gas formation. Some tumors and neoplasms (intestinal, uterine and others) are also accompanied by the development of anaerobic microorganisms. With anaerobic infections, an unpleasant odor may appear, however, its absence does not exclude anaerobes as the causative agent of the infection.

Features of obtaining and transporting samples

The very first test in identifying infections caused by anaerobes is a visual examination. Various skin lesions are a common complication. Also, evidence of the vital activity of bacteria will be the presence of gas in infected tissues.

For laboratory tests and establishing an accurate diagnosis, first of all, you need to competently get a sample of matter from the affected area. To do this, they use a special technique, thanks to which normal flora does not get into the samples. The best method is straight needle aspiration. Obtaining laboratory material using the smear method is not recommended, but is possible.

Samples that are not suitable for further analysis include:

• sputum obtained by self-excretion;
• samples obtained during bronchoscopy;
• smears from the vaginal vaults;
• urine with free urination;
• feces.

The following can be used for research:

• blood;
• pleural fluid;
• transtracheal aspirates;
• pus obtained from the abscess cavity;
• cerebrospinal fluid;
• lung punctures.

Transport samples it is necessary as quickly as possible in a special container or plastic bag with anaerobic conditions, since even short-term interaction with oxygen can cause the death of bacteria. Liquid samples are transported in a test tube or in syringes. Swabs with samples are transported in tubes with carbon dioxide or pre-prepared media.

If an anaerobic infection is diagnosed, the following principles must be followed for adequate treatment:

• toxins produced by anaerobes must be neutralized;
• the habitat of bacteria should be changed;
• the spread of anaerobes must be localized.

To comply with these principles antibiotics are used in treatment, which affect both anaerobes and aerobic organisms, since often the flora in anaerobic infections is mixed. At the same time, when prescribing medications, the doctor must evaluate the qualitative and quantitative composition of the microflora. Agents that are active against anaerobic pathogens include: penicillins, cephalosporins, clapamphenicol, fluoroquinolo, metronidazole, carbapenems and others. Some drugs have limited effect.

To control the habitat of bacteria, in most cases, surgical intervention is used, which involves treating affected tissues, draining abscesses, and ensuring normal blood circulation. Surgical methods should not be ignored due to the risk of life-threatening complications.

Sometimes used auxiliary treatment methods, and also because of the difficulties associated with accurately identifying the causative agent of the infection, empirical treatment is used.

When anaerobic infections develop in the oral cavity, it is also recommended to add as many fresh fruits and vegetables to the diet as possible. The most useful for this are apples and oranges. Meat foods and fast food are subject to restrictions.

1. Characteristics of anaerobes

2. Diagnostics of EMKAR

1. Distribution of anaerobic microorganisms in nature.

Anaerobic microorganisms are found everywhere where organic matter decomposes without access to O2: in different layers of soil, in coastal silt, in piles of manure, in ripening cheese, etc.

Anaerobes can also be found in well-aerated soil, if there are aerobes that absorb O2.

Both beneficial and harmful anaerobes are found in nature. For example, in the intestines of animals and humans there are anaerobes that benefit the host (B. bifidus), which plays the role of an antagonist to harmful microflora. This microbe ferments glucose and lactose and produces lactic acid.

But there are putrefactive and pathogenic anaerobes in the intestines. They break down proteins, cause rotting and various types of fermentation, and release toxins (B. Putrificus, B. Perfringens, B. tetani).

The breakdown of fiber in the animal body is carried out by anaerobes and actinomycetes. This process mainly takes place in the digestive tract. Anaerobes are mainly found in the forestomach and large intestine.

A large number of anaerobes are found in the soil. Moreover, some of them can be found in the soil in vegetative form and reproduce there. For example, B. perfringens. As a rule, anaerobes are spore-forming microorganisms. Spore forms have significant resistance to external factors (chemicals).

2. Anaerobiosis of microorganisms.

Despite the diversity of physiological characteristics of microorganisms, their chemical composition is, in principle, the same: proteins, fats, carbohydrates, inorganic substances.

Regulation of metabolic processes is carried out by the enzymatic apparatus.

The term anaerobiosis (an - negation, aer - air, bios - life) was introduced by Pasteur, who first discovered the anaerobic spore-bearing microbe B. Buturis, capable of developing in the absence of free O2 and facultative ones, developing in an environment containing 0.5% O2 and can bind it (for example, B. chauvoei).

Anaerobic processes - during oxidation, a series of dehydrogenations occur, in which “2H” are sequentially transferred from one molecule to another (ultimately O2 is involved).

At each stage, energy is released, which the cell uses for synthesis.

Peroxidase and catalase are enzymes that promote the use or removal of H2O2 formed during this reaction.

Strict anaerobes do not have mechanisms for binding to oxygen molecules, therefore they do not destroy H2O2. The anaerobic action of catalase and H2O2 is reduced to the anaerobic reduction of catalase iron by hydrogen peroxide and to aerobic oxidation by the O2 molecule.

3. The role of anaerobes in animal pathology.

Currently, the following diseases caused by anaerobes are considered established:

EMKAR – B. Chauvoei

Necrobacillosis – B. necrophorum

The causative agent of tetanus is B. Tetani.

It is difficult to differentiate these diseases based on their course and clinical signs, and only bacteriological studies make it possible to isolate the corresponding pathogen and establish the cause of the disease.

Some anaerobes have several serotypes and each of them causes different diseases. For example, B. perfringens - 6 serogroups: A, B, C, D, E, F - which differ in biological properties and toxin formation and cause different diseases. So

B. perfringens type A – gas gangrene in humans.

B. perfringens type B – B. lamb – dysentery – anaerobic dysentery in lambs.

B. perfringens type C – (B. paludis) and type D (B. ovitoxicus) – infectious enteroxemia of sheep.

B. perfringens type E – intestinal intoxication in calves.

Anaerobes play a certain role in the occurrence of complications in other diseases. For example, with swine fever, paratyphoid fever, foot-and-mouth disease, etc., as a result of which the process becomes more complicated.

4. Methods for creating anaerobic conditions for growing anaerobes.

There are: chemical, physical, biological and combined.

Nutrient media and cultivation of anaerobes on them.

1.Liquid nutrient media.

A) Meat peptone liver broth - Kitt-Torozza medium - is the main liquid nutrient medium

To prepare it, use 1000 g of bovine liver, which is poured with 1.l tap water and sterilized for 40 minutes. At t=110 C

Dilute with 3 times the amount of MPB

I set pH = 7.8-8.2

For 1 l. broth 1.25 g. Nacle

Add small pieces of liver

Vaseline oil is layered onto the surface of the medium.

Autoclave t=10-112 C – 30-45 min.

B) Brain environment

Ingredients: fresh cattle brain (no later than 18 hours), peeled and minced in a meat grinder

Mix with water 2:1 and pass through a sieve

The mixture is poured into test tubes and sterilized for 2 hours at t=110

Solid culture media

A) Zeismer blood sugar agar is used to isolate a pure culture and determine the growth pattern.

Zeissler agar recipe

3% MPA is bottled in 100 ml. and sterilize

Add sterile to molten agar! 10 ml. 20% glucose (t.s. 2%) and 15-20 ml. sterile blood of sheep, cattle, horse

Dried

B) gelatin - in a column

To determine the type of anaerobes, it is necessary to study the following characteristics:

Morphological, cultural, pathological and serological, taking into account their potential for variability.

Morphological and biochemical properties of anaerobes

Morphological features are characterized by pronounced diversity. The forms of microbes in smears prepared from organs differ sharply from the forms of microbes obtained in artificial nutrient media. More often they have the form of rods or threads and less often cocci. The same pathogen can be in the form of rods or in grouped threads. In old cultures it can be found in the form of cocci (for example, B. Necrophorum).

The largest are B. Gigas and B. Perfringens with a length of up to 10 microns. And the width is 1-1.5 microns.

Somewhat less than B. Oedematiens 5-8 x 0.8 –1.1. At the same time, the length of Vibrion Septicum filaments reaches 50-100 microns.

Among anaerobes, most are spore-forming microorganisms. The spores are located differently in these microorganisms. But more often it is Clostridium type (closter - spindle). The spores can have a round oval shape. The location of the spores is characteristic of certain types of bacteria: in the center - rods B. Perfringens, B. Oedematiens, etc., or subterminally (somewhat closer to the end) - Vibrion Septicum, B. Histolyticus, etc. and also terminally B. Tetani

Spores are produced one at a time per cell. Spores usually form after the death of the animal. This feature is related to the functional purpose of spores as the preservation of the species in unfavorable conditions.

Some anaerobes are motile and the flagella are arranged in a peritric pattern.

The capsule has a protective function and contains reserve nutrients.

Basic biochemical properties of anaerobic microorganisms

Based on their ability to decompose carbohydrates and proteins, anaerobes are divided into saccharolytic and proteolytic.

Description of the most important anaerobes.

Feser - 1865 in the subcutaneous tissue of a cow.

B. Schauvoei is the causative agent of an acute non-contact infectious disease that mainly affects cattle and sheep. The pathogen was discovered in 1879-1884. Arluenk, Korneven, Thomas.

Morphology and coloring: in smears prepared from pathological material (edematous fluid, blood, affected muscles, serous membranes) B. Schauvoei has the appearance of rods with rounded ends 2-6 microns. x 0.5-0.7 microns. Usually the sticks are found singly, but sometimes short chains (2-4) can be found. Does not form threads. It is polymorphic in shape and often has the shape of swollen bacilli, lemons, spheres, and disks. Polymorphism is especially clearly observed in smears prepared from animal tissue and media rich in proteins and fresh blood.

B. Schauvoei is a movable rod with 4-6 flagella on each side. Does not form capsules.

The spores are large, round to oblong in shape. The spore is located centrally or subterminally. Spores are formed both in tissues and outside the body. On artificial nutrient media, the spore appears within 24-48 hours.

B. Schauvoei is stained with almost all dyes. In young cultures G+, in old ones -G-. Rods perceive color granularly.

EMCAR diseases are septic in nature and therefore Cl. Schauvoei are found not only in organs with pathological abnormalities, but also in pericardial exudate, pleura, kidneys, liver, spleen, lymph nodes, bone marrow, skin and epithelial layer, and blood.

In an unopened corpse, bacilli and other microorganisms multiply rapidly, and therefore a mixed culture is isolated.

Cultural properties. On IPPB Cl. Chauvoei produces abundant growth in 16-20 hours. In the first hours there is uniform turbidity, by 24 hours there is a gradual clearing, and by 36–48 hours the broth column is completely transparent, and at the bottom of the test tube there is a sediment of microbial bodies. With vigorous shaking, the sediment breaks up into a uniform turbidity.

On Martin's broth - after 20-24 hours of growth, turbidity and abundant gas evolution are observed. After 2-3 days there are flakes at the bottom, the medium clears.

Cl. Chauvoei grows well on brain medium, producing small amounts of gases. Blackening of the medium does not occur.

On Zeismer agar (blood) it forms colonies similar to a mother-of-pearl button or grape leaf, flat, with a raised nutrient medium in the center, the color of the colonies is pale purple.

B. Schauvoei coagulates milk within 3-6 days. Coagulated milk has the appearance of a soft, spongy mass. Peptonization of milk does not occur. Does not liquefy gelatin. It does not liquefy curdled whey. Indole does not form. Nitrites are not reduced to nitrates.

Virulence on artificial nutrient media is quickly lost. To maintain it, it is necessary to carry out a passage through the body of guinea pigs. In pieces of dried muscle it retains its virulence for many years.

B. Schauvoei decomposes carbohydrates:

Glucose

Galactose

Levulez

Sucrose

Lactose

Maltose

Does not decompose - mannitol, dulcite, glycerin, inulin, salicin. However, it must be recognized that the ratio of Cl. Chauvoei to carbohydrates is fickle.

On Veillon agar + 2% glucose or serum agar, round or lentil-like colonies with shoots form.

Antigenic structure and toxin formation

Cl. Chauvoei has an O - somatic-thermostable antigen, several H-antigens - thermolabile, as well as a spore S-antigen.

Cl. Chauvoei - causes the formation of agglutinins and complement binding antibodies. Forms a number of strong hemolytic, necrotizing and lethal protein toxins that determine the pathogenicity of the pathogen.

Resistance is due to the presence of spores. It can be stored in rotting corpses for up to 3 months, in heaps of manure with remains of animal tissue - 6 months. Spores persist in the soil for up to 20-25 years.

Boiling depending on the nutrient medium 2-12 minutes (brain), broth cultures 30 minutes. – t=100-1050С, in muscles – 6 hours, in corned beef – 2 years, direct sunlight – 24 hours, 3% formalin solution – 15 minutes, 3% carbolic acid solution has a weak effect on spores, 25% NaOH – 14 hours, 6% NaOH – 6-7 days. Low temperature has no effect on spores.

Sensitivity of animals.

Under natural conditions, cattle are sick at the age of 3 months. up to 4 years. Animals up to 3 months do not get sick (colostral immunity), over 4 years old – animals have suffered from the disease in a latent form. Disease up to 3 months cannot be ruled out. and over 4 years old.

Sheep, buffaloes, goats, and deer also get sick, but rarely.

Camels, horses, pigs are immune (cases have been reported).

Humans, dogs, cats, chickens are immune.

Laboratory animals - guinea pigs.

The incubation period is 1-5 days. The progression of the disease is acute. The disease begins unexpectedly, the temperature rises to 41-43 C. Severe depression stops chewing gum. Often the symptoms are causeless lameness, which indicates damage to the deep layers of the muscles.

Inflammatory tumors appear in the torso, lower back, shoulder, less often the sternum, neck, submandibular space - hard, hot, painful, and soon become cold and painless.

Percussion - tempo sound

Palpation - crupitation.

The skin takes on a dark blue color. Sheep - wool sticks out at the site of the tumor.

The duration of the illness is 12-48 hours, less often 4-6 days.

Pat. anatomy: the corpse is very swollen. Bloody foam with a sour smell (rancid oil) is released from the nose. The subcutaneous tissue at the site of muscle damage contains infiltrates, hemorrhage, and gas. The muscles are black-red in color, covered with hemorrhages, dry, porous, and crunch when pressed. Shells with hemorrhages. The spleen and liver are enlarged.

Anaerobes are microbes that can grow and reproduce without access to free oxygen. The toxic effect of oxygen on anaerobes is associated with the suppression of the activity of a number of bacterial bacteria. There are facultative anaerobes, capable of changing the anaerobic type of respiration to aerobic, and strict (obligate) anaerobes, which have only anaerobic respiration.

When cultivating strict anaerobes, chemical methods for eliminating oxygen are used: substances capable of absorbing oxygen are added to the environment surrounding the anaerobes (for example, an alkaline solution of pyrogallol, sodium hydrosulfite), or substances that are capable of reducing the incoming oxygen are introduced (for example, etc.) . It is possible to provide anaerobes by physical means: mechanically removing them from nutrient media before sowing by boiling, followed by filling the surface of the medium with liquid, and also using an anaerostat; inoculate by injecting into a high column of nutrient agar, then filling it with viscous vaseline oil. A biological way to provide oxygen-free conditions for anaerobes is through combined, joint sowing of crops and anaerobes.

Pathogenic anaerobes include rods, pathogens (see Clostridia). See also .

Anaerobes are microorganisms that can exist and develop normally without access to free oxygen.

The terms “anaerobes” and “anaerobiosis” (life without access to air; from the Greek negative prefix anaer - air and bios-life) were proposed by L. Pasteur in 1861 to characterize the conditions of existence of butyric acid fermentation microbes he discovered. Anaerobes have the ability to decompose organic compounds in an oxygen-free environment and thus obtain the necessary energy for their life activity.

Anaerobes are widespread in nature: they live in the soil, sludge of reservoirs, compost heaps, in the depths of wounds, in the intestines of people and animals - wherever decomposition of organic substances occurs without access to air.

With respect to oxygen, anaerobes are divided into strict (obligate) anaerobes, which are unable to grow in the presence of oxygen, and conditional (facultative) anaerobes, which can grow and develop both in the presence of oxygen and without it. The first group includes most anaerobes from the genus Clostridium, bacteria of lactic and butyric acid fermentation; the second group includes cocci, fungi, etc. In addition, there are microorganisms that require a small concentration of oxygen for their development - microaerophiles (Clostridium histolyticum, Clostridium tertium, some representatives of the genus Fusobacterium and Actinomyces).

The genus Clostridium unites about 93 species of rod-shaped gram-positive bacteria that form terminal or subterminal spores (color fig. 1-6). Pathogenic clostridia include Cl. perfringens, Cl. oedema-tiens, Cl. septicum, Cl. histolyticum, Cl. sordellii, which is the causative agent of anaerobic infection (gas gangrene), pulmonary gangrene, gangrenous appendicitis, postpartum and post-abortion complications, anaerobic septicemia, as well as food poisoning (Cl. perfringens, types A, C, D, F).

Pathogenic anaerobes are also Cl. tetani is the causative agent of tetanus and Cl. botulinum is the causative agent of botulism.

The genus Bacteroides includes 30 species of rod-shaped, non-spore-forming, gram-negative bacteria, most of which are strict anaerobes. Representatives of this genus are found in the intestinal and genitourinary tracts of humans and animals; some species are pathogenic, causing septicemia and abscesses.

Anaerobes of the genus Fusobacterium (small rods with thickening at the ends, do not form spores, gram-negative), which are inhabitants of the oral cavity of humans and animals, in association with other bacteria cause necrobacillosis, Vincent's sore throat, and gangrenous stomatitis. Anaerobic staphylococci of the genus Peptococcus and streptococci of the genus Peptostreptococcus are found in healthy people in the respiratory tract, mouth, vagina, and intestines. Cocci-anaerobes cause various purulent diseases: lung abscess, mastitis, myositis, appendicitis, sepsis after childbirth and abortion, peritonitis, etc. Anaerobes from the genus Actinomyces cause actinomycosis in humans and animals.

Some anaerobes also perform useful functions: they contribute to the digestion and absorption of nutrients in the intestines of people and animals (butyric acid and lactic acid fermentation bacteria), and participate in the cycle of substances in nature.

Methods for isolating anaerobes are based on creating anaerobic conditions (reducing the partial pressure of oxygen in the medium), to create which the following methods are used: 1) removing oxygen from the medium by pumping out air or replacing it with an indifferent gas; 2) chemical absorption of oxygen using sodium hydrosulfite or pyrogallol; 3) combined mechanical and chemical oxygen removal; 4) biological absorption of oxygen by obligate aerobic microorganisms sown on one half of a Petri dish (Fortner method); 5) partial removal of air from the liquid nutrient medium by boiling it, adding reducing substances (glucose, thioglycolate, cysteine, pieces of fresh meat or liver) and filling the medium with petroleum jelly; 6) mechanical protection from atmospheric oxygen, carried out by sowing anaerobes into a high column of agar in thin glass tubes according to the Veillon method.

Methods for identifying isolated cultures of anaerobes - see Anaerobic infection (microbiological diagnostics).