Mushrooms represent a separate kingdom of the animal world. They have many forms: edible, poisonous, mold, yeast and many others. Modern science knows more than five hundred species of mushrooms. These creatures are found everywhere on our planet, even within man. Some of them get along well with people and constitute opportunistic microflora. A pathogenic fungus necessarily causes a disease. He indulges his nature and seeks to win a place under the sun, as well as resources for further growth and development. Unfortunately, this is harmful to human health.
Definition
Pathogenic fungi are pathogens of deep and superficial mycoses in humans and animals. These creatures belong mainly to the class of dermatophytes, that is, eating skin. Less common among them are lower fungi and actinomycetes.
They have a certain affinity for animal tissues. This means that dermatophytes prefer the epidermis with the scalp, yeast - the lymphatic system, candida - parenchymal organs, aspergillus live in the respiratory system, and actinomycetes love to settle in the bones.
Knowing these features, the doctor can differentiate diseases and prescribe specific treatment.
Classification of pathogenic fungi
In the kingdom of mushrooms, pathogenic mushrooms are divided into two sections: mucus membranes and true mushrooms. The latter is divided into seven classes, the names of which reflect their inherent stages of development:
- citridomycetes;
- hypocytridomycetes;
- oomycetes;
- zygomycetes;
- ascomycetes;
- basidomycetes;
- deuteromycetes.
The first four representatives form a group of lower mushrooms, the rest belong to the higher ones, and the last class to imperfect mushrooms. Most 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 body. Spores (mushroom seeds) are lengthened and take the form of a tube that continues to grow and thin out in order to eventually become a hypha and become the basis of the mycelium. Already at this stage, the difference is noticeable. Gifa of higher mushrooms has partitions, and lower - no. Hyphae from different spores grow, intertwine with each other and eventually mycelium grows on a substrate.
For the diagnosis and production of drugs, pathogenic species of fungi are grown on nutrient media such as Saburo, Chapek-Doksa, wort and wort agar. A prerequisite is a pH below seven.
Mushroom cells are covered with a wall of carbohydrates, but the substance by which species can be determined remains chitin. It does not interact with penicillins and lysozyme, therefore, it has greater virulence for the human body.
Pathogenic fungus is resistant to physical and chemical disinfectants. Treatment from them can cause irreparable harm to human organs and systems, since a high concentration of drugs in body fluids is required. Microspores are most sensitive to therapy, and candida is least sensitive. The selection of drugs is complicated by the fact that in one species of fungi various combinations of antigens are possible, and toxins, enzymes and other pathogenicity factors are still unknown.
Features of infection in humans
Mushrooms pathogenic for humans can cause diseases that can be divided by localization into four groups:
- Deep mycoses are damage to the parenchymal organs, sepsis, and dissemination of spores from the focus of the disease to neighboring tissues.
- Subcutaneous mycoses, they are also subcutaneous. Mushrooms populate the epidermis, dermis, subcutaneous fat, fascia and even bones.
- Epidermomycoses or dermatomycoses occur on derivatives of the upper layer of the skin: hair and nails.
- Superficial mycoses (keratomycoses). Pathogenic fungi on the skin affect only the stratum corneum and hair.
A separate group distinguishes diseases, the causative agents of which are opportunistic fungi. These are opportunistic diseases that appear when the body’s immune defenses are weakened, such as HIV, hepatitis B or C, and cancer.
Most often, the pathogens of mycoses are found in soil or dust, so it is important to work in respirators, wash vegetables and herbs, and carry out wet cleaning indoors. Deep mycoses appear after inhalation of the pathogen, and for the development of skin diseases it is necessary that the spores fall on the wound surface.
Immunity
When a pathogenic fungus enters the body, it 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, therefore people are often allergic 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 titer of antibodies, by which it is possible to determine the stage of infection, as well as in the form of activation of the complement system in the classical and alternative way.
Diagnosis of mycosis
The easiest way to identify a pathogenic fungus is microscopy. Patients are taken blood, mucus and skin from the affected areas, applied to slides, stained or treated with acids, and then placed in a light or electron microscope. This procedure allows you to consider the morphological characteristics of the pathogen and determine its type.
Sometimes in the laboratory fungi are sown on selective media and observed on their growth and fermentation of various substances. This helps to identify the pathogen from a biochemical point of view.
In response to the introduction of pathogenic fungi, antibodies appear in human blood, the presence of which can be determined by serological research methods. However, the result of this procedure may be inaccurate, since different types of fungi contain cross-reacting antigens.
In epidemiological studies, skin tests were used to identify that part of the population that was already ill with fungal infections. This made it possible to find out whether the body had previously encountered this type of antigen or not. This method cannot be used for diagnosis, since it has low specificity.
Rod Candida
To date, 186 species of the Candida genus have been isolated, but only some of them can cause diseases in humans. For example, C. albicans, C. pseudotropicalis, C. tropicalis, C. krusei, C. parapsilosis, C. Quillermondii and others.
These are opportunistic fungi that are constantly located in the human intestines. They grow well on carbohydrate-rich environments. The colonies consist of their small oval cells intertwined with filaments of mycelium. They reproduce very quickly in the blood at a normal temperature of 37 degrees, in just three hours, thousands of new hyphae form from several spores. Germination of cells in the tissue is accompanied by a strong local immune response with the formation of pus.
In a healthy person and animals in the oral cavity, fungi of the genus Candida are sown in 50 percent of cases , almost always in feces, and up to 10 percent on the skin and genital mucosa. Whether the disease develops depends largely on the state of the immune and endocrine systems. Candidiasis can provoke drug therapy with immunosuppressants, glucocorticosteroids, cytostatics, radiation sickness, long-term antibiotic treatment, cancer and oral contraceptives.
Pathogenic fungi cause diseases on the background of diabetes mellitus, dysfunction of the endocrine glands and others. Recently, the number of iatrogenic candidiasis has significantly increased after surgical and diagnostic interventions. In addition, damage to the skin and mucous membranes by a fungus of the genus Candida is one of the markers of AIDS.
Pneumocystis pneumonia
Pneumocystis carinii is a fungus that primarily affects the tissues of the respiratory system. In order to look at its cultural properties, not enough ordinary culture media, it is necessary to use chicken embryos or transplantable cell cultures.
Cysts are round cells, inside of which basophilic bodies are visible. In the colony around mature cysts, young and intermediate forms are always located. The presence of intracellular bodies allows scientists to attribute pneumocysts to the class of actinomycetes.
These fungi cause pneumonia, but in some cases it is possible to damage other internal organs: the kidney, spleen, lymphatic system, retina, eye, heart, liver, pancreas and even the brain. Infection, as a rule, occurs in children against a background of reduced immunity.
Aspergillosis
This mushroom forms smooth green colonies that grow well at a person’s body temperature, but do not tolerate heat. Often found in food, wood. They cause an acute infection after a large amount of spores enters the human body along with food, such as bread. Often the disease develops a second time, against the background of blood pathologies, sarcoma, tuberculosis, corticosteroid therapy, immunosuppressive therapy. Not transmitted from person to person.
Most often affects the respiratory system, sometimes causing skin diseases such as eczema. Around the mycelium, tissues are necrotic; granulomas appear in the lesion. A characteristic feature is the occurrence of cavities in the affected areas that contain fungal balls. In the literature, cases of generalized infection with damage to the central nervous system are described.