What is a pathogenic fungus?

Mushrooms are a separate kingdom of the animal kingdom. They have many forms: edible, poisonous, mold, yeast and many others. Modern science knows more than five hundred species of fungi. These creatures are found everywhere on our planet, even within a person. Some of them get along well with people and form a conditionally pathogenic microflora. Pathogenic fungus necessarily causes disease. He indulges his nature and seeks to win his place under the sun, as well as resources for further growth and development. Unfortunately, this harms a person's health.

Definition

Pathogenic fungi are pathogens of deep and superficial mycoses in humans and animals. These creatures refer mainly to the class of dermatophytes, that is, eating skin. Less common are lower fungi and actinomycetes.

They have a certain tropism for the tissues of animals. This means that dermatophytes prefer the epidermis with the scalp, the yeast - the lymphatic system, the candida - the parenchymal organs, the aspergillus live in the respiratory system, and the actinomycetes adore settling in the bones.

Knowing these features the doctor can differentiate the diseases and prescribe a specific treatment.

Classification of pathogenic fungi

In the realm of fungi, pathogenic fungi are divided into two sections: sludge and real mushrooms. The latter is divided into seven classes, the names of which reflect the inherent stages of development:

- Citridomycetes;
- Hypocytidomycetes;
- oomycetes;
- Zygomycetes;
- Ascomycetes;
- basidomycetes;
- deuteromycetes.

The first four representatives form a group of lower fungi, the rest belong to the higher, and the last class to imperfect fungi. Most of the pathogenic fungi that cause disease in humans are deuteromycetes.

Properties of pathogenic fungi

A person usually does not immediately notice that pathogenic fungi have entered his organism. Spores (seeds of mushrooms) are lengthened and take the form of a tube that continues to grow and thin out, so that eventually it becomes a hyphae and become the base of the mycelium. Already at this stage, there is a marked difference. The Gifa of the higher fungi has septa, and the lower ones do not. Hyphae from different spores grow, intertwine with one another and eventually a mycelium grows on the substrate.

For the diagnosis and production of drugs, pathogenic species of fungi are grown on nutrient media, such as Saburo, Czapeka-Doksa, on wort and wort agar. A prerequisite is pH below seven.

Mushroom cells are covered with a wall of carbohydrates, but chitin remains a substance by which species can be determined. It does not interact with penicillins and lysozyme, therefore it has a greater virulence for the human body.

The pathogenic fungus is resistant to physical and chemical disinfectants. Treatment of them can cause irreparable harm to human organs and systems, since a high concentration of drugs in body fluids is required. The microspores are the most sensitive to therapy, and the least candida. The choice of drugs is complicated by the fact that different combinations of antigens are possible in one species of fungi, and toxins, enzymes and other pathogenicity factors are still unknown.

Features of infection in humans

Mushrooms, pathogenic for humans, are capable of causing diseases that can be divided into four groups by localization:

1. Deep mycosis is the defeat of parenchymal organs, sepsis, dissemination of spores from the source of the disease to neighboring tissues.
2. Subcutaneous mycoses, they are subcutaneous. Fungi colonize the epidermis, dermis, subcutaneous fatty tissue, fascia and even bones.
3. Epidermomycoses or dermatomycoses occur on the derivatives of the upper layer of the skin: hair and nails.
4. Superficial mycoses (keratomycosis). Pathogenic fungi on the skin affect only the stratum corneum and hair.

A separate group is isolated diseases, the causative agents of which are opportunistic fungi. These are opportunistic diseases that occur when the body's immune defenses are weakened, for example, HIV, hepatitis B or C, an oncological disease.

Most pathogens of mycoses are found in soil or dust, so it is important to work in respirators, wash vegetables and greens, and do wet cleaning in rooms. Deep mycoses appear after inhaling the pathogen, and for the development of skin diseases it is necessary that spores get on the wound surface.

Immunity

Pathogenic fungus, entering the body, causes a cascade of immune system reactions necessary to identify the antigen and develop specific protection against it.

As a rule, all fungi are strong immunogens, so people often have an allergy to them. The reaction develops as a delayed-type hypersensitivity or a cytotoxic type. In addition, T-helpers stimulate tissue macrophages to eliminate spores. Humoral reactions are manifested in the form of a high antibody titer, which can determine the stage of infection, as well as activation of the complement system along the classical and alternative pathways.

Diagnosis of fungal infections

The easiest way to identify a pathogenic fungus is by microscopy. Patients take blood, mucus and skin from the affected areas, apply to slides, stain or treat with acids, and then place in a light or electron microscope. This procedure allows us to consider the morphological features of the pathogen and determine its appearance.

Sometimes in the laboratory, mushrooms are sowed on selective media and observed on their growth and fermentation of various substances. This helps from the biochemical point of view to identify the pathogen.

In response to the introduction of pathogenic fungi, antibodies appear in human blood, the fact of which can be determined by serological methods of investigation. However, the result of such a procedure may be inaccurate, since different types of fungi contain cross-reacting antigens.

In epidemiological studies, in order to identify the part of the population that has already been infected with fungal infections, skin tests were used. This made it possible to know whether the organism had previously encountered this type of antigens or not. For diagnostics, this method can not be used, since it has low specificity.

Gender of the candidate

To date, 186 species of the genus have been identified, but only some of them can cause disease in humans. For example, C. albicans, C. pseudotropicalis, C. tropicalis, C. krusei, C. parapsilosis, C. Quillermondii, and others.

This is a conditionally pathogenic fungus, which is constantly in the human intestine. They grow well in environments rich in carbohydrates. Colonies consist of their small oval cells interwoven with filaments of mycelium. Very quickly multiply in the blood at a normal temperature of 37 degrees, in three hours of several spores thousands of new hyphae are formed. Germination of cells in the tissue is accompanied by a strong local immune response with the formation of pus.

A healthy person and animals in the oral cavity plant mushrooms of the genus Candida in 50 percent of cases , in feces almost always, on the skin and mucosa of the genital tract, up to 10 percent. Whether the disease will develop depends largely on the state of the immune and endocrine systems. Provocative candidiasis can be medicated by immunosuppressors, glucocorticosteroids, cytostatics, radiation sickness, prolonged antibiotic treatment, cancer and oral contraceptive use.

Pathogenic fungi cause diseases on the background of diabetes mellitus, dysfunction of the endocrine glands and others. Recently, the number of iatrogenic candidiasis has increased significantly after surgical and diagnostic interventions. In addition, the defeat of the skin and mucous fungus of the genus Candida is one of the markers of AIDS.

Pneumocystis pneumonia

Pneumocystis carinii is a fungus that mainly infects the tissues of the respiratory system. In order to look at its cultural properties, not enough ordinary nutrient media, it is necessary to use chicken embryos or transplantable cell cultures.

Cysts are round cells, inside of which are visible basophilic bodies. In the colony around mature cysts, young and intermediate forms are always located. The presence of intracellular bodies allows scientists to classify pneumocysts as a class of actinomycetes.

These fungi cause pneumonia, but in some cases, other internal organs can also be affected: kidney, spleen, lymphatic system, retina, heart, liver, pancreas and even brain. Infection, as a rule, occurs in children against a background of reduced immunity.

Aspergillosis

This fungus forms smooth green colonies, which grow well at the temperature of the human body, but do not tolerate heat. Often found in food, wood. Causes an acute infection after getting a large number of spores into the human body together with food, for example bread. Often the disease develops again, against the background of blood pathologies, sarcoma, tuberculosis, corticosteroid therapy, immunosuppressors. It is not transmitted from person to person.

Most often affects the respiratory system, sometimes causes skin diseases, such as eczema. Around the mycelium, tissues are necrotic, granulomas appear in the lesion. A characteristic feature is the occurrence of cavities on the affected areas, which contain fungal balls. In the literature, cases of generalized infection with central nervous system damage are described.