Aspergillus application. How dangerous is black mold in the house for the human body and how to get rid of it
Aspergillosis- a human disease, mycosis, caused by certain types of mold fungi of the genus Aspergillus and manifesting itself primarily by involving the respiratory system as a result of allergic restructuring or a destructive infectious process, under certain conditions going beyond this system with the development of dissemination and specific damage to other organs.
Aspergillosis is the most common pulmonary mycosis. Aspergillus is found everywhere. They are isolated from soil, air, and even sulfur springs and distilled water.
Sources of aspergillus are ventilation, shower systems, old pillows and books, air conditioners, inhalers, humidifiers, construction and repair work, soil of indoor plants, food products (vegetables, nuts, ground black pepper, tea bags, etc.), rotting grass , hay, etc. The disease is often found in flour millers and pigeon feeders, because Pigeons suffer from aspergillosis more often than other birds.
Regions with high levels of Aspergillus spores in the environment are Sudan and Saudi Arabia. In the air of residential premises, higher concentrations of Aspergillus spores are usually detected than in the open air. Patients with diabetes are susceptible to Aspergillus infection, regardless of region. The disease is non-contagious and is not transmitted from person to person.
The most vulnerable zone of infection by aspergillosis pathogens is the respiratory tract, and the lungs and paranasal sinuses are the main sites of infection. Dissemination is observed in 30% of cases, and skin lesions develop in less than 5% of patients. The mortality rate for disseminated aspergillosis reaches 80%. After organ transplantation, invasive tracheobronchial and pulmonary aspergillosis develops in almost every fifth patient and is fatal in more than half of them. In intensive care units of surgical clinics, in patients with AIDS, when using corticosteroid drugs in patients with chronic lung diseases, it occurs in 4% of patients.
Among invasive aspergillus infections, pulmonary aspergillosis should be put in first place (90% of lesions) - a serious disease with primary damage to the lungs and, often, paranasal sinuses (in 5-10% of patients), larynx, trachea and bronchi, with possible dissemination into the skin and internal organs. In the central nervous system it spreads as single/multiple brain abscesses, meningitis, epidural abscess or subarachnoid hemorrhage; myocarditis, pericarditis, endocarditis, osteomyelitis and discitis, peritonitis, esophagitis are also noted; primary aspergillus granulomatosis of the lymph nodes, skin and ear, endophthalmitis, aspergillosis of the external auditory canal, mastoiditis. In addition, Aspergillus can cause bronchial asthma and allergic bronchopulmonary aspergillosis, and also contribute to the development of exogenous allergic alveolitis, sometimes combined with IgE-dependent bronchial asthma (when working with rotten hay, barley, etc.).
Allergic bronchopulmonary aspergillosis (ABPA) is a condition in which a hypersensitive state of the lungs develops, induced predominantly by A. fumigatus, or a chronic inflammatory disease of the lungs in immunocompetent individuals, caused by a combined allergic reaction of types I, III and IV in response to constant exposure to Aspergillus antigens (endogenous or exogenous). In the United States, ABPA occurs in 7-14% of patients with chronic asthma treated with corticosteroids. Many patients with cystic fibrosis have Aspergillus colonization of the airways, and approximately 7% of these patients develop ABPA.
What provokes / Causes of Aspergillosis:
The most common cause of pathology is A. fumigatus, less commonly – A. flavus, A. niger, A. terreus, A. nidulans, A. clavatus. The listed species may be resistant to amphotericin B (especially A. terreus, A. nidulans), but sensitive to voriconazole. A. clavatus and A. niger can cause allergic conditions, A. flavus is a common pathogen in humans. A. niger often causes otomycosis and, along with A. terreus, colonizes open cavities of the human body.
ABPA patients are atopic and have a genetically determined T-cell response.
Pathogenesis (what happens?) during Aspergillosis:
Infection occurs in people at risk through inhalation of conidia, as well as when they come into contact with the wound surface and with food. Under favorable conditions, Aspergilla colonizes the bronchial mucosa with the possible development of massive vegetation and invasion into the bronchi and lung tissue, often with vascular germination, the formation of inflammatory changes and granulomas, which leads to the development of necrotizing inflammation, bleeding, and pneumothorax. When mold fungi invade the body's tissues, different types of tissue reactions are microscopically distinguished, namely serous-desquamative, fibrinous-purulent, as well as various types of productive reactions, up to the formation of tuberculoid granulomas.
The most common premorbid background for the development of aspergillosis are:
- use of systemic corticosteroid drugs in a dose of more than 5 mg per day (for collagen diseases, including ankylosing spondylitis, rheumatoid arthritis, Raynaud's syndrome), which leads to dysfunction of macrophages and inhibition of T-lymphocytes;
- cytostatic chemotherapy leading to neutropenia in the blood (less than 0.5x109) (for oncohematological diseases, organ transplantation);
- prolonged agranulocytosis in leukemia, aplastic anemia, chronic granulomatosis, etc.;
- granulocyte dysfunction (chronic granulomatous disease, Chediak-Higashi syndrome, etc.);
- diabetes;
- decreased clearance of fungal spores in lung diseases: chronic obstructive pulmonary disease, cystic fibrosis, bronchiectasis and lung cysts, disorders of pulmonary architecture (cystic hypoplasia of the lung, pulmonary fibrosis), tuberculosis, sarcoidosis, granulomatous lung diseases, conditions after lung resection, etc.;
- chronic peritoneal dialysis (with the development of peritonitis and subsequent dissemination to other organs);
- burn wounds, surgical interventions, injuries;
- placement of venous catheters (with possible local contamination of the skin), self-adhesive dressings in the area of placement of catheters;
- alcoholism with impaired liver function;
- cachexia and severe chronic diseases;
- malignant neoplasms;
- intensive and long-term antibiotic therapy;
- HIV infection and AIDS;
- a combination of these factors.
Summarizing all the conditions in which aspergillus is determined and/or plays a role, we can distinguish carriage/colonization, invasion and allergic condition, while mycosensitization and allergy can acquire a dominant independent character. For patients with defects in the immune system, Aspergillus carriage/colonization is very dangerous and can easily develop into invasion and dissemination.
The risk group for developing mycogenic allergies includes people with bronchial asthma, chronic bronchitis, especially among people associated with mushrooms by professional activity (poultry farmers, livestock farmers, workers at microbiological enterprises, pharmacy workers, libraries, mushroom pickers, etc.).
Symptoms of Aspergillosis:
Aspergillosis has a variety of clinical manifestations, which is determined by the immune status of the patient. In immunocompetent individuals, aspergillosis can be asymptomatic - in the form of carriage, colonization, or aspergilloma. With the deepening of immune disorders, it can transform into an invasive form, which, depending on the degree of immune defects, has a chronic, subacute or acute course, and the more pronounced the immunological deficiency, the more acute the course of the disease.
For acute invasive sinus aspergillosis(in immunocompromised patients) the pathogen penetrates into the mucous membrane with the formation of areas of necrosis. Non-invasive aspergillosis paranasal sinuses is a relatively rare disease in immunocompetent individuals. It usually appears in one sinus in the form of a spherical fungal formation (aspergilloma), and can remain in this form for months or years. Chronic subclinical invasive aspergillosis nasal sinuses occurs less frequently, develops in immunocompetent individuals in the sinuses, lasts for years and represents a chronic fibrosing granulomatous inflammation with slow spread to the orbits, skull bones, and brain. Its causative agent is usually A. flavus (in contrast to A. fumigatus, the most common causative agent of aspergillosis in immunocompromised individuals). This form of aspergillosis is usually associated with a high content of A. flavus conidia in the environment, especially in countries with hot, dry climates in tropical and desert regions.
In young immunocompetent individuals with nasal congestion and prolonged episodes of allergic rhinitis, asthmatic conditions, headaches, and nasal polyps, allergic fungal sinusitis cannot be excluded. In advanced cases, erosive damage to the ethmoid bones of the skull is possible.
Pulmonary aspergilloma is often considered as benign saprophytic colonization and develops in individuals with an unfavorable premorbid background and impaired lung function (pulmonary fibrosis, cysts, cavities in sarcoidosis, tuberculosis, emphysema, hypoplasia, histoplasmosis). Pulmonary aspergilloma is defined as a mobile conglomerate of intertwined aspergillus hyphae located in the lung cavity or bronchiectasis, covered with fibrin, mucus and cellular elements (the degree of darkening corresponds to liquid), located inside an oval or spherical capsule, separated from it by an air layer, with thickening of the pleura. With the beginning of the invasion of micromycetes into the lung tissue, hemoptysis may be observed - a characteristic symptom of aspergilloma, which occurs due to vascular damage due to the action of endotoxins and proteolytic enzymes, the development of thrombosis and the growth of mycelium into the vascular walls, as well as the formation of areas of necrosis. Hemoptysis can cause asphyxia, bleeding, leading to death in approximately 26% of patients with aspergilloma. It can lead to the formation of invasive and chronic necrotizing aspergillosis against the background of a fungal-bacterial mixed infection.
On an x-ray of the lungs, pulmonary aspergilloma appears as a round formation, sometimes movable, located inside a spherical or oval capsule and separated from the wall of this capsule by an air layer of various shapes and sizes. The intensity of the darkening on radiography of aspergilloma corresponds to liquid. With its peripheral location, thickening of the pleura is characteristic. An additional diagnostic criterion for establishing a diagnosis is the precipitation reaction, which for aspergilloma has 95% sensitivity (except for patients receiving corticosteroid drugs).
Pulmonary aspergillosis does not have pathognomonic features. The diagnosis is difficult to establish.
Chronic necrotizing pulmonary aspergillosis(CNPA) is a chronic or subacute infection, most often diagnosed in immunocompetent patients with impaired local defense in the presence of risk factors that change the general immune status. According to clinical manifestations, CNPA is a borderline form between invasive pulmonary aspergillosis, manifested by pneumonia, and aspergilloma.
Presumable mechanism for the formation of CNPA: in patients with moderately severe immunosuppression, after inhalation of spores and their penetration into the small bronchi, local damage to the bronchial wall by micromycetes occurs, followed by invasion of micromycetes into the pulmonary parenchyma, which is accompanied by tissue necrosis, thrombosis, phlebitis, arteritis, and an inflammatory reaction. In this case, necrotic tissue and fungal elements are sequestered into the newly formed cavity. Molds also have the ability to grow through tissues and, in the absence of adequate treatment, they penetrate through the walls into the cavities of other alveoli and vessels.
The following are described clinical forms of CNPA:
- Local invasive lesions of the bronchi, possibly with bronchiectasis and necrotizing granulomatous bronchitis, with mushy or dense sputum of greenish-brown or gray color, possibly with formations obstructing the bronchus, which are a fungal conglomerate fixed to the wall of the bronchus, similar in composition to aspergilloma, which can lead to formation of atelectasis. This form includes aspergillosis of the bronchial stump after a pulmonectomy for malignant tumors in the lungs, which can occur several years after the operation. It is possible that any case of CNPA begins with local damage to the bronchial wall and either remains a local process or progresses to pneumonia.
- Chronic disseminated (“miliary”) aspergillosis with clearly limited foci of necrotic Aspergillus invasive process, associated with massive inhalation of Aspergillus spores.
- Chronic destructive pneumonia, in which progressive ones of various localization and size are determined, often - upper lobe pulmonary infiltrates with cavities, combined with thinning of the pleura. This form of aspergillosis was previously called "pseudotuberculosis" due to its clinical similarity to tuberculosis. In the presence of this form, concomitant histoplasmosis, chronic granulomatous disease, and HIV infection should always be excluded.
Such patients may experience cough with sputum, fever, chest pain, weight loss, and hemoptysis (in 10% of patients). However, there is usually no significant intoxication and fever (unlike acute invasive bronchial lesions, for example, in patients with neutropenia), which is due to a less pronounced degree of immunosuppression. Pneumonia with CNPA does not have the same rate of development as is observed with acute invasive aspergillosis, and, at the same time, does not always have a clear picture of aspergilloma. X-ray examination reveals cavitary infiltrates that do not change over time or progress with mycetoma inside or without it, combined with thinning of the pleura, as well as focal dissemination.
CNPA is the rarest and most difficult to diagnose form of aspergillosis.
Acute invasive aspergillosis described in immunocompromised patients, its course is severe, and is characterized by the following symptoms:
- persistent fever or its return during therapy with broad-spectrum antibiotics;
- the appearance of new or progression of old infiltrates in the lung tissue during antibacterial therapy;
- severe “pleural” pain in the chest;
- clinical signs of pneumonia - “non-productive cough”, sputum streaked with blood, there may be pulmonary hemorrhage, pain in the chest when breathing, wheezing and pleural friction noise are possible on auscultation;
- signs of sinusitis with destruction of bone tissue, determined by X-ray or computer studies; periorbital pain and swelling, nosebleeds;
- maculopapular lesions on the skin with necrosis;
- detection of fungal mycelium during cytological or histological studies;
- isolation of Aspergillus culture by culture from the nasal cavity, sputum, bronchoalveolar fluid, blood and other substrates.
Acute pulmonary aspergillosis can occur in the form of:
- hemorrhagic infarction;
- progressive necrotizing pneumonia;
- endobronchial infection.
X-ray of the lungs reveals subpleurally located focal rounded shadows or triangular shadows, connected to the pleura at the base; As the disease progresses, cavities appear. A computed tomography scan of the lungs determines the presence of round-shaped foci surrounded by a halo (“halo”, a symptom of a halo or corolla - “halo sign”) of lesser density, which, in fact, is edema or hemorrhage around the ischemic focus and is observed more often in the first 10 days. The so-called “crescent sign” or “sickle sign” (“air crescent sign”) is visible later and reflects the formation of necrosis due to the migration of neutrophils to the lesions and the development of an inflammatory reaction. However, similar signs are found in other pathologies.
In immunocompromised patients, localized aspergillosis of the larynx, trachea and bronchi may develop.
Aspergillus tracheobronchitis are a rarer manifestation of acute invasive aspergillosis. They can be observed sequentially: nonspecific redness of the mucosa, first with mucus plugs, then fibrinous endobronchitis, diffuse hemorrhagic changes in the mucosa, and sometimes pseudomembranous tumor-like formations, which may contain granulation tissue and hyphae and cause obstruction of the upper respiratory tract, can be detected. Sometimes there is abundant secretion. Colonization and damage to the bronchi is the first stage in the development of acute pulmonary aspergillosis. Clinically, fever, shortness of breath, cough, dry wheezing, weakness, fatigue, often weight loss, and varying degrees of airway obstruction may be observed.
Allergic bronchopulmonary aspergillosis (ABPA). The following classical ABPA criteria are known:
- presence of a diagnosis of bronchial asthma/cystic fibrosis;
- persistent and transient infiltrates in the lungs;
- positive skin tests with A. fumigatus antigen;
- eosinophilia of peripheral blood (more than 500 per mm3);
- determination of precipitating antibodies and specific IgG and IgE to A. fumigatus;
- high level of total immunoglobulin E (more than 1000 ng/ml);
- isolation of A. fumigatus culture from sputum or bronchial washings;
- presence of central bronchiectasis.
A decrease in vital capacity of the lungs is observed in 60% of patients with ABPA, peripheral blood eosinophilia - in 80%, central or proximal saccular bronchiectasis, especially in the upper lobes, is present in 80% of patients. It has been shown that bronchiectasis can occur due to the release of proteolytic enzymes by micromycetes and eosinophils. In bronchiectatic cavities, in turn, colonies of fungi can develop, which become a constant source of antigens.
Pulmonary infiltrates are recorded in approximately 85% of patients. Thus, a typical radiological sign of ABPA is inconsistent one- or two-sided areas of compaction in the lungs, mainly in the upper sections, which is caused by obstruction of the bronchi with mucus plugs. A bronchus filled with mucus produces a darkening in the form of a band or finger of a glove on an x-ray. Such shadows are characteristic of the disease. They may change after coughing up the mucus plug. The photographs may show ring-shaped or parallel shadows (“tram rails”), which represent inflamed bronchi. But often no changes are observed. As ABPA progresses, pulmonary fibrosis (“honeycomb lung”) develops.
The diagnosis of ABPA should be assumed in all patients with hormone-dependent bronchial asthma, cystic fibrosis, or when bronchial asthma is combined with the above-described radiological signs.
P.A. Greenberger et al. (1986) identified 5 stages of ABPA.
Stage I – acute (infiltrates in the lungs, high levels of total IgE, blood eosinophilia);
Stage II – remission (there are no infiltrates in the lungs, the IgE level is slightly lower, there may be no eosinophilia);
Stage III – exacerbation (indicators correspond to the acute stage);
Stage IV – corticosteroid-dependent bronchial asthma;
Stage V – fibrosis (“honeycomb lungs”).
The trigger for the formation of ABPA is probably an acute respiratory infection (acute respiratory infection, influenza, pneumonia, acute bronchitis), manifested by an increase in body temperature, discharge of a kind of brown, gray or white sputum with mucoid plugs, which was noted in the history of all patients with ABPA, as well as inhalation of fungal spores Aspergillus spp. in critical quantities.
A variety of ABLA can be the classic forms of allergic alveolitis: “farmer’s lung”, “cheese washer’s lung”, “lung of a worker engaged in producing malt” in brewing, among woodcutters, etc.
Diagnosis of Aspergillosis:
If Aspergillus is detected in the sputum of immunocompetent individuals, find out:
- presence of occupational hazards in the anamnesis;
- the nature of production and living conditions;
- presence of symptoms of diabetes mellitus;
- condition of the nasopharynx;
- duration and frequency of antibiotic treatment for other diseases;
- presence of chronic nonspecific lung diseases, duration of exacerbation, presence and nature of anti-inflammatory basic therapy.
When identifying aspergillus in the sputum of immunocompromised individuals, find out:
- the amount and nature of previous antibiotic therapy, corticosteroids and chemotherapeutic agents;
- level of CD4+ lymphocytes in the blood, number of neutrophilic granulocytes in the blood;
- the presence of fungal infections of other organs (ENT pathology, central nervous system, etc.).
Repeated isolation of Aspergillus cultures from sputum/ALS in immunocompetent individuals more often reflects the presence of respiratory tract colonization. In cases of unclear infiltrates in the lungs in immunocompromised patients in the absence of effect from antibacterial therapy, the isolation of Aspergillus in sputum should be considered as an etiological factor and require specific therapy. If there is no dynamics after 7 days of intensive antifungal therapy, then the diagnosis can be considered unconfirmed.
Repeated determination of antigenemia (galactomannan) and detection of a radiographic “crown sign” in patients at risk is considered equivalent to a biopsy with detection of mycelium, regardless of the isolation or non-isolation of a pure Aspergillus culture.
Laboratory research
Mandatory
- Microscopy (sputum/ALS, biopsy, etc.) for the presence of aspergillus:
- microscopy of unstained preparations using the hanging or crushed drop method.
- microscopy of stained preparations (hematoxylin-eosin, impregnation according to Gomorry-Grocott, calcofluor white, etc.).
- Cultural diagnostics with repeated examinations of the material (to exclude false-positive results):
- culture of material on Sabouraud, Czapek-Dox medium (aspergilli are rarely found in the blood, bone marrow and cerebrospinal fluid) - in immunocompromised individuals, detection of an aspergillus culture most likely indicates invasive aspergillosis.
- Serological diagnosis:
- with the determination of galactomannan antigen A. fumigatus in blood serum, cerebrospinal fluid, urine, etc.:
using the radioimmunoassay method (RIA-Radioimmunoassay);
ELISA method (Enzyme-Linked Immunosorbent Assay) (true positive results for determining galactomannan are more likely when its titer is high in adult patients, and false positive results are more likely in children).
- Determination of specific antibodies in blood serum:
IgG (for the diagnosis of chronic necrotizing aspergillosis, aspergilloma);
IgG, IgE (diagnosis of ABPA).
- Polymerase chain reaction (PCR) method - to determine fragments of Aspergillus nucleic acids or their metabolic products, for example, glycan and mannitol (up to 25% of false positive results are possible) (additional diagnostics).
If indicated
- In order to establish a diagnosis: histological examination of biopsy material with hematoxylin-eosin staining, Gomory-Grocott impregnation, calcofluor white, Gribley, McManus, etc.
- Diagnostics of the intensity of exogenous intake of micromycetes: detection of secretory IgA to fungal antigens and mycotoxins in saliva.
Instrumental and other diagnostic methods
Mandatory
- X-ray examination and computed radiography of the chest organs to determine the presence of lung damage.
- Bronchoscopy with obtaining bronchoalveolar lavage for microscopic and cultural examination.
If indicated
- To obtain material for the purpose of cultural and histological diagnosis - biopsy of lesions.
Specialist consultations
Mandatory
- Otolaryngologist – to exclude fungal infection of the ENT organs.
Treatment of Aspergillosis:
Pharmacotherapy
Due to the low effectiveness of treatment of invasive aspergillosis, averaging 35% (when treated with amphotericin B), in immunocompromised patients, when aspergillosis is suspected even before laboratory evidence is obtained, there is often a need for empirical antifungal therapy. Anti-Aspergillus treatment must be carried out simultaneously with the normalization of the patient’s immune status (with the elimination of neutropenia, CD4+ lymphocytopenia), as well as treatment of hemoptysis.
The dosage of antifungal drugs and duration of treatment are determined individually.
For invasive aspergillosis, the drugs of choice are: Voriconazole (J02AC03) (initially 6 mg/kg, then 4 mg/kg twice daily, and later 200 mg oral twice daily) and Amphotericin B (J02AA01) (1 ,0-1.5 mg/kg/day) or its form – (J02AA01) (3-5 mg/kg/day), (J02AA01) (0.25-1.0-1.5 mg/kg/day ) and etc.
Second-line drugs include Itraconazole (J02AC02) (dosage when taken orally – 400-600 mg/day for 4 days, then 200 mg twice a day; intravenously – 200 mg twice a day, then 200 mg). It is preferably used in patients with less immunosuppression. Caspofungin (J02AX04) is also used, initially 70 mg once a day, then 50 mg intravenously daily. It is effective in the absence of the effect of other antifungal agents.
For brain damage, the listed drugs are used in combination with flucytosine (J02AX01) (150 mg/kg per day), which penetrates the cerebrospinal fluid.
After stabilization until stable relief of clinical, laboratory and instrumental signs (usually at least 3 months), Itraconazole (J02AC02) 400-600 mg/kg/day is indicated.
Fluconazole (J02AC01) is not active against Aspergillus spp.
Short courses of oral corticosteroids in the treatment of ABPA (prednisolone 0.5-1 mg/kg/day) eliminate bronchial mucus blockage in patients with ABPA. The consumption of corticosteroid drugs and the number of exacerbations in patients with ABPA may be reduced with prophylactic treatment with itraconazole (200 mg twice daily). Itraconazole may also be used to treat exacerbations of ABPA.
Surgical procedures
Mandatory
Patients with bleeding due to aspergilloma require lobectomy. If lung function is low, ligation or embolization of the bronchial artery is performed (used as a temporary measure). Systemic therapy is ineffective for endobronchial and cavity aspergillosis. Surgical excision of the lesion or curettage of the affected areas is performed. Surgical intervention is also indicated for centrally located foci of invasive aspergillosis near the mediastinum, when massive bleeding is possible.
When treating aspergilloma, surgery can be carried out under the protection of intravenous use of amphotericin B or their introduction into the cavity (in the amount of 10-20 mg of amphotericin B in 10-20 ml of distilled water). Serious postoperative complications (life-threatening pulmonary hemorrhages) are common. Therefore, the decision to perform surgical intervention is very difficult: resection of aspergilloma is possible only in patients with massive pulmonary hemoptysis and adequate lung function. There is limited evidence that itraconazole is somewhat effective in the treatment of aspergilloma.
Efficacy criteria and duration of treatment
The duration of treatment for aspergillosis is not strictly limited, since the effect of therapy, expressed in the elimination of fever and positive clinical and radiological dynamics, depends on the state of the immune system, background diseases, and the presence of a mixed infection (bacterial-fungal). The duration of treatment is individual and ranges from 7 days to 12 months.
Prevention of Aspergillosis:
Primary prevention
for patients with severe immunodeficiency - carrying out measures aimed at preventing the entry of Aspergillus conidia into the air, which is achieved by using expensive rooms or chambers with laminar air flows, or installing various airlocks between rooms and air filters.
Since favorable conditions are created in the soil for the development of mold fungi, indoor plants should not be placed in the wards of patients with reduced immunity. At the first manifestations of the disease, the patient should be isolated, indoor flowers removed, air ducts, air conditioners and damp surfaces checked. If Aspergillus is detected, surfaces should be treated with disinfectants.
Relapse Prevention
. For immunocompromised persons - prohibition of excavation, agricultural work, contact with animals, restriction of stay in dusty and humid places, prohibition of consumption of stale and moldy foods, cheeses, etc.
Which doctors should you contact if you have Aspergillosis:
Is something bothering you? Do you want to know more detailed information about Aspergillosis, its causes, symptoms, methods of treatment and prevention, the course of the disease and diet after it? Or do you need an inspection? You can make an appointment with a doctor– clinic Eurolab always at your service! The best doctors will examine you, study external signs and help you identify the disease by symptoms, advise you and provide the necessary assistance and make a diagnosis. you also can call a doctor at home. Clinic Eurolab open for you around the clock.
How to contact the clinic:
Phone number of our clinic in Kyiv: (+38 044) 206-20-00 (multi-channel). The clinic secretary will select a convenient day and time for you to visit the doctor. Our coordinates and directions are indicated. Look in more detail about all the clinic’s services on it.
(+38 044) 206-20-00
If you have previously performed any research, Be sure to take their results to a doctor for consultation. If the studies have not been performed, we will do everything necessary in our clinic or with our colleagues in other clinics.
You? It is necessary to take a very careful approach to your overall health. People don't pay enough attention symptoms of diseases and do not realize that these diseases can be life-threatening. There are many diseases that at first do not manifest themselves in our body, but in the end it turns out that, unfortunately, it is too late to treat them. Each disease has its own specific signs, characteristic external manifestations - the so-called symptoms of the disease. Identifying symptoms is the first step in diagnosing diseases in general. To do this, you just need to do it several times a year. be examined by a doctor, in order not only to prevent a terrible disease, but also to maintain a healthy spirit in the body and the organism as a whole.
If you want to ask a doctor a question, use the online consultation section, perhaps you will find answers to your questions there and read self care tips. If you are interested in reviews about clinics and doctors, try to find the information you need in the section. Also register on the medical portal Eurolab to be constantly aware of the latest news and information updates on the site, which will be automatically sent to you by email.
Are you about to cut bread and see velvety black spots formed by multiplied mold? Or did you suddenly begin to suffer from allergies, although you had never noticed anything like this before?
The culprit is black mold, which you encounter from time to time in your own home or apartment. Agree, it’s not very pleasant to see black growths of mold on products whose existence was forgotten for some reason, or on the walls in the bathroom, or, even worse, on the wallpaper in the nursery.
We will help you deal with such an unwanted neighbor. Although it is not so easy to destroy it, its appearance cannot be tolerated. To find ways to get rid of such a scourge, in this article we’ll talk about why black mold is dangerous in the house, what types of mold can live indoors, and what options for getting rid of it can be used at home.
To help in the fight against this terrible enemy, we have also selected visual video tutorials on how to destroy the fungus and tips on preventing its occurrence.
If you don't look closely, it may seem that black mold is just emerging dirt that can be easily gotten rid of. But that's not true.
Black mold is an external manifestation of a colony of microscopic fungi. Moreover, these colonies can form different types of fungi. The varieties listed below are most often found in our homes.
Image gallery
Fungus #1 - Aspergillus black
(Aspergillus niger) is a saprophyte that has chosen rooms with high humidity: kitchens, bathrooms, toilets or combined bathrooms, swimming pools.
Colonies of this fungus often form in humidifiers and even air conditioners.
Damp ceilings and walls, covers of old books, and pots for indoor plants are often covered with this black mold. The favorite place for the colony of Aspergillus niger to appear is in bathrooms.
This is how cute and cute mold can look under a microscope, which can deprive a person of not only health, but also life itself.
This fungus looks quite nice in the photo, but its presence is not at all harmless.
Thanks to them, completely harmless diseases can arise:
- meningitis;
- myoarditis;
- bronchial asthma or even pneumonia;
- rhinitis.
The presence of spores of this fungus can cause the formation of papillomas and even cancer cells.
If a person happens to inhale a large number of spores at once, he may develop intoxication of the body. With a weakened immune system, which is not uncommon these days, there is a risk of death.
It is Aspergillus niger that can cause pulmonary aspergilloma. Volatile spores of the fungus can easily penetrate through the nasopharynx into the trachea, and then affect the bronchi, alveoli and bronchioles. Once established, they begin to develop rapidly.
Toxins released by the colony contribute to the formation of foci of necrosis. As a result, the parenchymal tissue of the lungs ceases to function, suffocation and death occur.
Fungus #2 - Aspergillus fuming
The peculiarity of this mold is that it can withstand increases in ambient temperature from 12 to 53 degrees.
Fungal spores ( Aspergillus fumigates) are very small: only 2-3.5 microns, so they easily penetrate into the lungs of animals and humans. Healthy people can inhale several hundred spores of this fungus without consequences.
But in a person with a weak immune system, the risk of aspergillosis increases many times over.
These colonies, isolated in a Petri dish and surrounded by a greenish glow, are a very dangerous enemy that has no place in our homes.
When renovation work is carried out near hospitals and clinics where there may be patients with reduced immunity, the risk of infection of patients increases sharply.
In such situations, it is considered necessary to conduct air monitoring to detect cases of high concentrations of pathogenic spores.
Most often, Aspergillus fumigates affects fruits and vegetables that have mechanical damage.
If fungi have infected the grains from which baked goods are subsequently baked, black fluffy spots or mold deposits will quickly form on the baked goods.
Fuming Aspergillus is dangerous because the toxins that accompany its activity are allergens. They are capable of destroying red blood cells that make up the blood. In addition, the toxins of this fungus can suppress the production of immunity.
Fungus #3 - Alternaria alternata
Another type of spore-forming mold fungi is Alternaria alternata (Alternaria tenuis).
The appearance of the colonies of this fungus depends on the nutrient medium on which they are formed. Most often these are dark gray, almost black, spots. But they can also have a greenish-olive tint.
This fungus lives on a dying part of a plant. Its colonies can be found on autumn leaves, overripe fruits, and even just on the surface of the soil.
This mold can grow on food, including pork, as well as textiles. The toxins of the fungus infect plants and poison grain seeds.
You've probably come across this onion or other vegetable on sale more than once, infected with black mold: under no circumstances bring it home
Not only fungal spores, but also its fragments can be found both outside and inside the home, concentrating in house dust. The risk of Alternaria tenuis colonies is higher in homes with a humid atmosphere.
Regular ventilation of rooms, regardless of weather conditions and time of year, helps to avoid the formation of mold colonies in the house.
Reason #2 - everyone's favorite drywall
And how can you not love this building material, if with its help you can level any horizontal or vertical surface so easily and quickly. It is plasterboard that allows you to erect partitions of any configuration in the shortest possible time.
This very inexpensive material is really convenient to use in repairs and construction, which is why it enjoys well-deserved popularity.
Of course, plasterboard structures are convenient, beautiful and economical, but when creating them, do not forget that this material is hygroscopic
But this material also has a significant flaw: drywall absorbs moisture well, allowing it to linger inside for a long time.
In order to avoid being captured by black mold when using drywall, you must strictly follow the installation technology and remember that the mixtures must have time to dry.
In a room with drywall, you need to create an antifungal microclimate.
In rooms with high humidity levels, special drywall designed for such operating conditions should be used. In addition, antifungal drugs must be added to the solutions used during the work process.
Reason #3 - poor ventilation
A window in a bathroom is a real rarity. As a rule, the layout of our apartments does not provide not only windows in the bathrooms, but also sufficiently effective ventilation.
Meanwhile, a lot of humid air can form in bathrooms as a result of drying clothes or water procedures for which this room is intended. It is difficult for natural exhaust channels to cope with it.
Poor ventilation in the bathroom, combined with high humidity and heat, creates ideal conditions for the formation and spread of black mold.
One method to solve this problem is to use . Thanks to this measure, the problem of excess humidity will be solved, and at the same time, conditions for the development of mold microflora will not arise.
Read more about removing mold in the bathroom.
Reason #4 - damp basements and damp walls
Quite often, miscalculations in design can lead to the fact that during rain the walls or corner parts of buildings get wet, and freeze in the cold part of the year.
The same problem occurs when drainpipes are missing or clogged. If you do not pay attention to this, then over time mold colonies may form on the walls.
Gradually, the fungus grows through the brickwork or panels and ends up indoors. Invasion will occur even faster than might be expected if there are cracks in the brickwork or the panel joints are not well waterproofed.
It’s a shame if you bring black mold into your home and also pay money for the product on which it is found: contaminated grain produces contaminated bread
The source of mold may be in a damp basement. In it, colonies can form and multiply, and then, using ventilation ducts, they spread throughout all rooms.
In a private house, this problem is solved independently by arranging high-quality furniture. To eliminate dampness in an apartment building, you will have to contact the housing office.
Faulty sewerage and water supply also create conditions for the development of fungi.
We can bring black mold into our home ourselves, without meaning to. It is enough to buy bread products baked from contaminated grain in the store.
Such bread will very quickly become covered with plaque and then mold. Under no circumstances should you eat it: it is dangerous to your health. It is also not suitable for animal feed.
It should be placed in a plastic bag and then placed in an outdoor trash bin.
Subtleties of fighting black mold
If you find black mold in your apartment, then you need to deal with this neighborhood without delay. The longer colonies remain in your home, the more damage they can cause to health, and the more difficult it will be for them to survive.
Image gallery
It must be stated right away that The use of bactericidal agents in the fight against mold will not help. These drugs are designed to kill bacteria, not fungi.
The ultraviolet radiation emitted by the lamp is destructive to fungal colonies; it is not for nothing that black mold prefers shady places outside buildings
An excellent and very effective way to get rid of mold is to treat the room with UV lamps. Under the influence of ultraviolet rays, the spores die.
When using this lamp, it is necessary to observe some safety measures: remove pets from the room being treated, including birds and aquarium fish, and also remove all fresh flowers from the room.
There are other methods of combating mold fungi:
- If mold colonies are located on specific objects that can be taken out, they must be removed outside the home. Send old wallpaper, moldy textiles or contaminated putty to the landfill.
- Special antifungal drugs and antiseptics should be added to all construction and finishing mixtures that are used in the construction of a private house or when renovating your apartment. Often mold takes root in the tile joints in the kitchen and bathroom. This means that special attention should be paid to the grout.
- Areas affected by fungi can also be treated with special industrial preparations. In case of their absence, use the means that every housewife has.
If mold stains appear on non-porous surfaces, which include, for example, tiles or mirrors, then to eliminate them you can use the following popular substances: bleach "White", ammonia, borax solution or vinegar.
Can be applied to the affected surface hydrogen peroxide, and after 15 minutes, rinse the area with water. Baking soda has also proven itself to be excellent.
All surfaces on which traces of mold are present must be ruthlessly removed: it is better to do this job conscientiously once than to endlessly return to it
The situation is more complicated when colonies appear on the plaster: the entire affected part must be mechanically removed. It is better to do this with a wire brush.
Cleaning is carried out to the entire depth of mold penetration. The seams between the tiles are also cleaned with a sharp tool.
It is advisable to dry the cleaned surface using an industrial hair dryer and treat it with an antiseptic. Moreover, not only the area from which the mold has been removed should be treated, but also the adjacent surfaces.
Whichever of the methods listed above you choose, it is important that the mold is destroyed or, at worst, removed outside the apartment. Its appearance cannot be ignored. This is too dangerous a neighborhood that needs to be gotten rid of by any means.
We do not suggest that you use a gas mask or overalls as personal protective equipment, but glasses, a respirator and rubber gloves should be
Required Security Measures
Considering that spores, particles of mold itself and the toxins it releases can spread with air currents, gathering to fight fungal colonies, it is necessary to protect your respiratory tract and skin from unwanted contacts.
Safety precautions:
- Do not neglect personal protective equipment such as a respirator, waterproof gloves and safety glasses.
- To prevent spores that have been removed from one surface from taking root on another, the surfaces of the furniture and floor must be covered with oilcloth, which you don’t mind throwing away later, or with plastic film.
- Anything that can be taken out of the room during cleaning is best removed. In the bathroom this could include, for example, washcloths, brushes, towels and curtains.
- If the situation is serious and mold has managed to take over large areas of the room, all objects that can get fungal spores should be wrapped in film. Choose a thicker film to ensure reliable protection. It is not advisable to save on your health: then you will spend more on medicines.
- Never turn on the fan while cleaning. Mold spores can easily spread throughout the room, and then there is simply no escape from them: they can appear unexpectedly and in the most inappropriate places.
- Do not use a household vacuum cleaner to remove fungal colonies. The spores or toxins themselves may end up on the inside of this household appliance. The spores in the vacuum cleaner do not die, but simply wait in the wings and suitable conditions for the revival of the colonies.
- But the dehumidifier, if there is such a device in the house, should be turned on. Dried air will deprive microorganisms of the chance to continue existing.
- After cleaning the contaminated area, you must throw away all rags, brushes, gloves and films along with the respirator.
Mold control is an inevitable event in case mold has already started. But it is much better to prevent its occurrence by not creating conditions for the development of fungal colonies.
Image gallery
Conclusions and useful video on the topic
You can write a lot about how dangerous mold is, but it will not make the same impression as the stories of those who were once exposed to it.
It’s good that when people realize in time what is causing their troubles and poor health. The following video will help you understand the problems that arise from exposure to black mold:
This video clearly demonstrates the methods of preventing and combating fungal colonies.
Defeating your velvety enemy is not at all easy, but it is possible. It is much more important to ensure such living conditions in your home that mold does not grow in it at all. Don't leave her any chance to live.
Perhaps you also have experience dealing with insidious mold? Please tell us about proven methods for its destruction. Comment on the material and leave questions on the topic.
The vegetative body of Aspergillus is a large, very branched mycelium that penetrates the substrate. Mycelial cells are multinucleated. Sometimes abundant aerial mycelium also develops. In most Aspergillus, the mold coating consists of conidiophores with conidia. Conidiophores extend upward from special mycelial cells - supporting cells (Fig. 231). In different species, conidiophores have different sizes, can be a single cell or, less commonly, have septa, and in a few they have branches. In most Aspergillus, the conidiophores are colorless, like the mycelial hyphae, and in some (for example, in representatives of the A. nidulans, A. ochraceus groups) they are brownish or yellowish. Most of their shells are smooth, while a few (A. ochraceus group, A. effusus from the A. nidulans group) are spiny. The upper part of the conidiophore swells, forming a bubble, round in most, elongated to varying degrees in some species. On the bladder, either radially or only in its upper part, there are flag-shaped cells - phialides, from the narrow neck of which single-celled conidia emerge one after another, arranged in a chain. Directly at the opening at the top of the phialides, the conidia have a thin shell, are often colorless or pale colored, and their final maturation and formation occurs gradually. The higher up the chain, the larger the conidia, the more intensely colored and the more mature (Table 56). Mature conidia have a certain shape and color; in many aspergilli, they become spiny or tuberculate when ripe. The color of the mass of conidia is what gives one color or another to the mold plaque, i.e., the colony.
In some aspergilli, which are apparently at a higher stage of evolutionary development, an increase in the number of conidia formed occurs as a result of the fact that a series of cells (profialides) appear on the bladder of the conidiophore, on which phialides sit in bunches, or whorls (Fig. 231). At low microscope magnification, the tip of the conidiophore Aspergillus, carrying chains of conidia, looks very similar to the tip of a watering can, from the holes of which streams of water flow. Therefore, the Russian name for aspergillus is leechny mushroom. However, the exact translation of Aspergillus would be “shaggy head,” which also agrees very well with the impression made when viewing conidiophores with chains of conidia.
As they mature, the conidia fall off, are transferred to new places and germinate under favorable conditions, forming mycelium.
Most aspergillus reproduce with the help of conidia, i.e. asexually. However, some of them are also characterized by higher sporulation - marsupial, i.e. sexual. In colonies of such species, small balls are visible to the naked eye; most are yellow. These are fruiting bodies - cleistothecia. They were first discovered by G. Link (1809) in herbarium material.
Cleistothecia are preserved mainly in those aspergilli in which the conidiophores have a simpler structure: they do not carry on their bladder those additional elements (prolifelides) that are characteristic of species that have lost marsupial sporulation.
Currently, the marsupial stage is known in almost all species of the A. glaucus group, in all species of the A. fischeri series from the A. fumigatus group, in many species of the A. nidulans group and in some species of the A. ornatus, A cremeus and A. ochraceus groups . These fungi have phialides formed directly on the conidiophore bladder (without profialides).
The sclerotia formed in many species of Aspergillus from the groups A. candidus, A. niger, A. flavus and A. ochraceus are similar to cleistothecia. But, unlike cleistothecia, they are a simple plexus of mycelial hyphae and there are no bags inside. It can be assumed that sclerotia are cleistothecia that have lost the ability to form ascospores. This assumption is confirmed by the formation of marsupial sporulation inside the sclerotia, for example in A. alliaceus.
Sclerotia are especially abundant when the content of nitrates and sucrose in the medium is high and at a temperature of 20-25°C.
Sometimes similar in appearance formations observed in the colonies of some groups (A. nidulans, A. versicolor, A. ustus) can be mistaken for cleistothecia or sclerotia. These are clusters of spherical or convoluted cells with such thick membranes that the cavity of these cells is almost completely obliterated. Sometimes they are mistaken for chlamydospores. Indeed, in A. nidulans the germination of these cells into the mycelium was observed. However, the true nature of thick-walled cells has not been established.
Aspergillus, like penicillium and many other fungi, has additional mechanisms for the formation of new forms, in addition to the sexual process. The first report of heterokaryosis in A. niger (Table 58) and A. nidulans was published in 1940 by G. H. Gossop and co-workers. The parasexual process, an essential element of which is heterokaryosis, was also first demonstrated on A. nidulans in 1952 by J. E. Roper, and then on A. niger by L. Pontecorvo et al. Since then it has been comprehensively studied in many others species and genera of fungi.
The fact that it was Aspergillus that was subjected to such intensive study in this regard was by no means accidental. From about the middle of the 19th century. Aspergilli have already attracted attention as active agents in the processes of destruction of a wide variety of materials, as pathogens and the cause of toxicosis in animals and humans, as producers of various enzymes and other valuable metabolic products, successfully used in a number of industries. In addition, they grow well in laboratory conditions, which is why they have become one of the favorite subjects of research. Suffice it to say that between 1891 and 1928. More than 2,000 papers on Aspergillus have been published, focusing mainly on the physiology, biochemistry and genetics of these fungal species. Their study continues to this day. They have been especially active in working with Aspergillus in laboratories since 1940, when they began to be used as generally very convenient models in studies of genetic patterns, various physiological processes, metabolic pathways, etc.
Some groups and species of Aspergillus are widespread in nature and, as already mentioned, have very significant practical significance. These are primarily representatives of the A. niger group, most actively used in industry and in laboratory research. Since 1945, more than 1000 scientific articles have been devoted to the species of this group alone! They are isolated from the soil in different countries and on different continents, i.e. they are cosmopolitan. They develop on grain during storage, on fruits, vegetables, cotton products, leather and materials rich in proteins.
Colonies of species of the A. niger group are brown, chocolate or black (Table 58). Conidiophores bear profialides with whorls of phialids.
Species of the A. niger group are distinguished by diverse biochemical activities. They produce a variety of enzymes - amylolytic, proteinases, pectinase, lipase, glucose oxidase, enzymes that destroy the horny substance, chitin, etc. Already in 1787, the “fermentation” of gall nuts was described with the help of A. niger, which produces the tanase enzyme, with the formation of gall nuts acid, which is used to produce a number of paints, inks, and some pharmaceuticals. Currently, pectolytic enzymes from A. niger and A. foelidus are used in a number of countries to clarify fruit juices and wines. In Japan, pectolytic enzymes from A. niger are used to fiberize plant stems (ramie). The use of A. awamori enzymes allows the production of crystalline glucose from starch. Fructose can be obtained from inulin under the action of the A. niger enzyme, etc.
The ability of strains of A. niger and other species of this group to form citric, oxalic, gluconic, and fumaric acids has become widely used. In the USSR and other countries, strains of this species are used for the production of citric acid. Strains of the A. niger group are capable of synthesizing the vitamins biotin, thiamine, riboflavin, etc.
As for antibiotic substances, they are produced in limited quantities and their practical use is small.
The use of A. niger strains in various laboratory studies is diverse. At one time, this species was figuratively called the “biochemical frog” (L.I. Kursanov). Since they are very sensitive to mineral nutrition sources, it is possible to use specially selected strains to determine the deficiency of certain elements in the soil (phosphorus, potassium, copper, etc.) and vitamins, which turned out to be much simpler, more accurate and faster than chemical tests.
In a number of tropical countries, plant diseases caused by strains of A. niger have been reported, for example, seedlings of peanuts, cotton, and sorghum in East Africa (Sudan), and India. The fungus A. carbonarius has been described as a cause of grape blight in India.
A. niger strains isolated from moldy feed have proven toxic to animals. There are known cases of otomycosis, pulmonary aspergillosis, bronchopneumonia, and mycetomas of the extremities, the cause of which was A. niger.
Fungi of the A. flavus-oryzae group are no less important. They are characterized by a yellowish-green color of the colonies. Conidiophores in some species bear only phialides on their swellings, while in others they also carry profialides. These fungi are found in the soil and on a wide variety of substrates: plant debris, forage, food products, vegetable oils, plastics and other materials. A. flavus can grow even on such seemingly unsuitable substrates as wax and paraffin. Fungi of this group are the main components of the community of molds that develop on grains and seeds, mainly on rice, peas, soybeans, peanuts, in poorly ventilated storages, even at 18% humidity. The diversity of colonized substrates is explained by the fact that species of this group have a particularly rich set of enzymes. They produce amylase, proteinases, lipases, pectinases (pectase and protopectinase), cellulase, etc. That is why A. oryzae and related species have been used in the East for food and other purposes for centuries. The alcohol industry of Japan and other Eastern countries is entirely based on the enzymatic properties of mushrooms of this group. Enzymes from A. oryzae ("taka-koi") hydrolyze the starch of rice grains in the production of rice vodka - sake. Other sources of starch, such as sweet potato, are now being successfully used in Japan to produce industrial alcohol.
In the preparation of food products from soybeans and other protein-rich substrates in the East (mainly in Japan), proteolytic enzymes of A. flavus, A. oryzae, and A. parasiticus have been used for a century. In the production of Chinese and Japanese soy sauce by enzymatic method, a special starter is used, which is a culture of A. oryzae on boiled soybeans or pearl barley. In Vietnam, enzymatic soybean-rice sauce “Tuong” is an obligatory daily food product for the population. When preparing it, the proteolytic and amylolytic enzymes of molds, and better than others A. oryzae, hydrolyze the starch and proteins of soy and rice. In modern conditions, enzyme preparations of A. flavus, A. oryzae and A. parasiticus are successfully used to clean hair from skins and soften skins, to remove silver from old films and plates, and in the textile industry. In the USSR, enzymes from fungi of this group are also used, for example, for the manufacture of enzyme preparations, in the production of alcohols and for other purposes.
Currently, much attention is paid to the selection of strains with high α-amylase, maltase and protease activity.
This does not exhaust the list of useful metabolites. The ability of fungi of this group to form kojic acid was established at the beginning of this century. Kojic acid is produced by A. flavus, A. tamarii, A. parasiticus, A. effusus. They form other acids (β-nitropropionic, α-ketoglutaric, citric, malic, lactic, fumaric, etc.), as well as vitamins (riboflavin, thiamine, pantothenic acid, inositol, biotin, pyridoxine, B12, C, K3, etc. .) and steroids (testosterone, testololactone).
In recent years, A. flavus has become notorious for producing one extremely harmful toxic substance. The dramatic story of the discovery of this toxin begins in 1960, when a mysterious disease of turkeys appeared in England, in which they died in large numbers without any visible signs of already known diseases. On one of the farms, within two weeks, out of 1,000 young turkeys and poults, 800 died. And in a little more than three months, on farms that specialized in breeding turkeys, their number decreased by more than a hundred thousand.
The Scotland Yard Forensic Laboratory, the Animal Welfare Society and many other organizations took part in the investigation into the causes of the disease. Immediately, suspicion arose that the birdseed was poisoned, and they began to check it primarily for the content of dangerous chemicals, poisons and various pathogens. All these tests gave negative results. Then they noticed that all outbreaks of disease “X,” as it was called, occurred on farms that were supplied with feed by two factories that, as it turned out, added flour from groundnuts (peanuts) exported from Brazil to the feed.
It became known that in Kenya, ducklings died in a similar way when they were given food supplemented with groundnuts brought from Uganda. And then scientists at the London Institute of Tropical Crops found that the toxin is produced in large quantities by the fungus A. flavus, which quickly develops on groundnuts in conditions of high humidity and moderately high temperatures in the tropics and subtropics. The toxic substance was called aflatoxin (from the initial letters of the name of the fungus). Later it turned out that this is not one substance, but a whole complex (B1, B2, G1, G2). Subsequently, the carcinogenic nature of the toxin was established.
This discovery, in addition to medical significance, has great economic significance, since in many areas of the world the cultivation of groundnuts is one of the main branches of the economy. Some African countries depend almost entirely on the production and export of groundnuts and their oil. In this regard, ensuring proper storage of this product is of paramount importance, especially since subsequent experiments have shown, firstly, that aflatoxin has a harmful effect (toxic and carcinogenic) on a wide range of animals, not excluding, apparently, humans, and secondly, that many other fungi that develop on stored products, especially on ground nuts, flax and cotton seeds, liver, fish, etc., also produce toxic substances and can cause serious diseases.
It is impossible not to dwell in more detail on a representative of another group of aspergillus (A. fumigatus group) - A. fumigatus, which can often cause serious diseases in animals and humans. This fungus has two types of colonies: fluffy, in which aerial white mycelium is well developed and conidial sporulation is poorly represented, giving the colony a soft bluish tint, and velvety - with mycelium in the substrate and abundant conidial sporulation, which has a thick bluish-green color. When examining the colony under a low magnification microscope, it is clear that the chains of conidia on each conidiophore form together a dense column. On the surface of the conidiophore swelling there are only phialides, covering mainly its upper part.
A. fumigatus produces a toxin that has hemolytic and antigenic effects. The mycelium extract of this species is irritating to the skin and kidneys.
Aspergillus fuming(A. fumigatus) produces the antibiotic fumagillin, which is active against staphylococcal bacteriophage and, most importantly, has medicinal properties against amoebic dysentery, bee nosematosis, and actively inhibits the development of a number of continuous tumors. In the laboratory of antibiotics of Moscow State University under the leadership of Z. E. Becker and A. B. Silaev, a domestic preparation of crystalline fumagillin was obtained.
The alkaloid festuclavine, used in medicine and previously obtained only from ergot (Claviceps purpurea), and two new alkaloids, fumigaclavines A and B, were isolated from the mycelium of A. fumigatus.
Recently, the fungus A. fumigatus has been credited with an active role in the destruction of chitinous substances in soil. The wide distribution of strains of this fungus in various conditions, the diverse biochemical activity characteristic of them, especially at elevated temperatures, and great resistance (their mycelium and spores can remain viable after being in 60% alcohol for 6-8 minutes) are causing growing interest. to study this group.
Widely growing dark green velvety colonies of A. nidulans (Table 58) from the group of the same name are also quite often found on various materials of plant origin. Sometimes it is released from the soil and from the tissues of animals and humans, developing mainly in the lungs and air sacs of chickens, the lungs of horses, and in the ear canals of animals and humans.
Many species of the A. nidulans group produce bright yellow cleistothecia that stand out sharply against the dark background of the colony. Depending on the ratio of the number of cleistothecia and conidial sporulation, the color of the colonies changes from dark green, if conidial sporulation predominates, to bright yellow in the case of massive development of cleistothecia. The ascospores of species in this group are purple-red. Colonies usually contain thick-walled cells in the form of large yellow clusters.
It should be especially noted that the A. nidulans group ranks second after the species Neurospora genus(Neurospora) in fungal genetics. A large number of mutants have been obtained; the mechanism of formation of mitotic recombinations and the factors determining these processes, the formation of heterokaryons, cytoplasmic inheritance, etc. are being studied.
A. nidulans and mutants obtained from wild strains are used to study carbohydrate, nitrogen and other types of metabolism.
The A. versicolor group is very interesting and unique. Its representatives are characterized by the formation of narrow-growing, convex, dense colonies, various yellowish-green or bluish shades in the conidial zone, often with pink tones in the mycelial growth zone. On the reverse side, the colonies are bright red or cherry red. The same color pigment is released into the environment around the colonies.
The most common species are A. versicolor and A. sydowii. They are isolated from soils, especially of southern origin, and develop on grain, cheese and other products, on various materials of various equipment, auto coatings and car upholstery, especially in tropical and subtropical conditions. By releasing pigment, they spoil some products, forming brightly colored spots on them in those areas where colonies developed.
The fungus A. versicolor predominated on wheat imported to Italy from Argentina, USA, Syria and other countries. In museums in many cities, this mushroom was found on easel and monumental paintings. In libraries, where 80% of damage to leatherette, calico or leather bindings is caused by Aspergillus, it is more common than other fungi. The fight against this kind of damage is made difficult by the fact that the fungus is resistant to most antiseptics. Due to this property, it is widely used in the study of means used to protect various industrial products (for example, optical instruments, plastics, etc.) from fungi, to assess the resistance of paper to mold, to determine the effectiveness of fumigation and other types of soil treatment of growing houses and etc.
We have briefly covered the significance of only some Aspergillus species. However, what has been said is enough to imagine the enormous role they play in nature and human economic activity. The wide ecological amplitude characteristic of fungi of this genus makes it possible for the development of certain species under different environmental conditions. For example, it is known that most fungi, including Aspergillus, actively grow on organic materials at low pH values. It turns out that some of them (A. clavatus) are not only able to tolerate strong alkalization of the environment, but also cause this alkalization themselves, during which most fungi cannot develop. Due to this feature, species of the A. clavatus group often form mold deposits on animal tissues.
Many Aspergilli are characterized by xerophytism. Thus, some representatives of the largest group in terms of the number of species, A. glaucus (A. repens, A. ruber, A. amstelodami) and the A. ustus group, develop well on grain and other products, on textiles, insulating materials and other substrates under low humidity levels.
A wide range of enzymes allows Aspergillus to master a wide variety of substrates. The antibiotic substances produced by them ensure a successful fight against possible competitors. This creates prerequisites for the use of certain species in the development of biological control measures against phytopathogenic organisms.
Life of plants: in 6 volumes. - M.: Enlightenment. Edited by A. L. Takhtadzhyan, editor-in-chief, corresponding member. USSR Academy of Sciences, prof. A.A. Fedorov. 1974 .
Unlike highly specialized fungi from zycomycetes, in particular entomophthora fungi, most hyphal entomopathogenic fungi are characterized by broad specialization. This means that they do not require specific nutrients... ... Biological encyclopedia
Contents 1 Model organisms 1.1 Viruses 1.2 Archaea 1.3 Eubacteria ... Wikipedia
Marsupial fungi are a large and diverse group that constitute the division Ascomycota in the kingdom Fungi. The main feature of A. is the formation as a result of karyogamy (fusion of nuclei) and subsequent meiosis of sexual spores (ascospores) in special structures - bags, ... ... Dictionary of microbiology
Traditional... Wikipedia
Human Infectious disease Pathogen Bacillus cereus Bacillus cereus Bacteroides Bacteroides Baylisascaris Baylisascaris Burkholderia usually Burkholderia cepacia and other species of Burkholderia Clostridium difficile Clostridium difficile... ... Wikipedia
Definition, toxiconomic affiliation of mushrooms
Spores of fungi of this genus are present in the air almost constantly: every day each of us inhales about several hundred spores, which do not cause any diseases in a person with a normal immune system. AND Sometimes fungi of the genus Aspergillus can be found in the oropharynx of a healthy person.
As already described above, fungal spores can be present in indoor air, including in the air of hospitals, which can become a risk factor for nosocomial infection of an inpatient with a weakened immune system.
A number of representatives of fungi are used in industry to obtain organic acids, antibiotics, vitamins, enzymes, and for the industrial production of certain food products.
Description of appearance
Externally, upon microscopic examination, fungi of the genus Aspergillus are fungi consisting of the same type of mycelium, 4-6 micrometers wide, on which “heads” with conidia are sometimes present.
A specific bacteriological nutrient medium for growing colonies of fungi of this genus is the so-called Sabouraud medium. On it, mushrooms form flat colonies, at first white, slightly fluffy, which subsequently take on bluish, yellowish, brown and other colors depending on the species. Their surface becomes powdery.
Clinical significance
A peculiarity of this genus of fungi is the ability to cause not only allergic diseases, but also infectious lesions.
In terms of the frequency of development of specific infectious diseases, fungi of the genus Aspergillus occupy second place after yeast-like fungi of the genus Candida.
Predisposing factors to the development of Aspergillus infections are immunodeficiencies, including secondary immunodeficiencies caused by taking high doses of systemic glucocorticosteroids, for which the cellular and molecular mechanisms of increased vulnerability of organs and tissues to fungal spores have been studied, as well as chronic pulmonary diseases.
Aspergillus can affect any organs and tissues.
Clinical manifestations include the following forms:
- bronchopulmonary aspergillosis and its varieties: infectious-allergic bronchopulmonary aspergillosis, purulent bronchitis, chronic aspergilloma, invasive pulmonary aspergillosis, chronic necrotizing pulmonary aspergillosis;
- generalized (septic) aspergillosis, which occurs in immunocompromised people (for example, HIV infection) and has a high incidence of deaths;
- aspergillosis of ENT organs: external and media otitis, rhinosinusitis, aspergillosis of the larynx;
- aspergillosis of the eye;
- skin aspergillosis in the form of erythematous scales and papules, in more severe cases - necrotic lesions of subcutaneous fatty tissue;
- bone aspergillosis;
- other forms of aspergillosis (damage to the mucous membranes of the mouth, genitals, mycotoxicosis).
The most common respiratory lesions occur against the background of chronic lung diseases:
- bronchial asthma, cystic fibrosis - for allergic bronchopulmonary aspergillosis;
- pre-existing cavities in the lungs (tuberculous cavities, cavities in patients with sarcoidosis or other diseases resulting from the formation of cavities) - for aspergilloma;
- chronic obstructive pulmonary disease during its treatment with glucocorticosteroids - for necrotizing pulmonary aspergillosis.
Risk factors for the occurrence of invasive pulmonary aspergillosis, in addition to those listed above, are secondary immunodeficiency conditions, against the background of treatment with immunosuppressants, HIV infection, decompensated diabetes mellitus, massive treatment with antibiotics and other factors.
However, people with normal immune systems can also develop respiratory infections caused by Aspergillus fungi due to increased exposure to Aspergillus spores.
Massive inhalation of the spores of these fungi in healthy people can cause acute pneumonia, which usually resolves on its own.
Occupational risk factors for chronic diseases caused by spores of fungi of the genus Aspergillus are work in agriculture, weaving factories and paper spinning mills.
For fungi of the genus Aspergillus, this disease is called “malt workers’ lung” due to the high frequency of occupationally caused cases of diseases in these workers.
Also, some representatives of fungi of this genus can secrete toxic substances - aflatoxin, ochratoxin and sterigmatocystin, which, with chronic exposure, cause manifestations of mycotoxicosis - toxic hepatitis, kidney disease and even.
However, the main feature of fungi of the genus Aspergillus, which distinguishes them from representatives of other genera of molds, is the ability to cause specific infectious diseases.
Main allergens and fungal pathogenicity factors
Atopic diseases associated with sensitization to allergens of fungi of the genus Aspergillus are associated with the presence of allergens to which class E immunoglobulins are produced.
The number of main allergens varies depending on the species and in Aspergillus fumigatus reaches 19. The main ones are Asp f 1-ribotoxin, Asp f 3-peroxisomal protein, Asp f 5-metalloprotease and a number of other allergens, most of which are proteins with enzymatic activity
The release of proteolytic, saccharolytic and lipolytic enzymes into the environment is a factor that determines the ability to cause an active infectious process and exhibit invasive growth, for example, to grow into the bronchial wall to the basement membrane in invasive bronchopulmonary aspergillosis.
Another factor in the virulence (ability to cause an infectious disease) of fungi is a number of mechanisms of protection against phagocytosis (absorption by effector cells of the innate immune system).
Recently, the ability of the fungus Aspergillus fumigatus to form a protective film has been intensively studied, which allows fungal cells to attach to the cells of the host body, provides protection from effector mechanisms of immunity and even from modern antifungal drugs.
A number of toxic substances released by some representatives of fungi of this genus were indicated above.
Methods for identifying fungi and diagnosing diseases caused by fungi
Determining whether fungal spores in air samples belong to representatives of the genus Aspergillus is based on spore microscopy and bacteriological studies (determining the ability to grow on a special nutrient medium, the appearance of colonies).
Due to the high frequency of allergic diseases and the severe course of specific infections caused by these fungi, their often lack of specific clinical signs and the complexity of differential diagnosis, specific is of great importance.
Atopic sensitization to the allergens of these fungi is detected through skin tests and identification of specific immunoglobulins E to the allergens of these fungi, antibodies of other classes in specific infectious processes.
For respiratory infections caused by fungi, to identify fragments of the fungus, microscopy of sputum and material obtained during broncho-alveolar lavage during bronchoscopy is used, detection of fungal DNA in the above materials using polymerase chain reaction (PCR studies).) in conditions of massive contact with house dust, contact with areas of high humidity during cleaning is necessary not only for allergy sufferers with sensitization to mold allergens, but also for all patients with bronchial asthma.
Higher fungi of the genus Aspergillus are among the most widespread in nature, as they are resistant to environmental factors. Aspergillus fungi are members of the class of marsupial fungi. Their natural habitat is soil, often in areas with a warm climate. Aspergilli are aerobes and grow well on a variety of substrates. They can often be seen on plant foods in the form of a flattened, fluffy, colored mold deposit, mostly blue or green. For example, colonies of Aspergillus are noticeable on bread if storage rules are not followed, on jam, wallpaper in a room with high humidity, etc. “Black mold” sometimes appears on the walls of dark, damp rooms due to the development of Aspergillus niger (black aspergillus) in the fruiting stage. Thus, most Aspergillus are saprophytes, but among them there are species of fungi that are parasitic for humans and animals. They cause diseases such as aspergillosis. Aspergillosis develops in most cases in people suffering from immunodeficiency. The route of entry of the fungus is through the upper respiratory tract. The characteristic symptoms of the disease develop when the respiratory, nervous systems, and gastrointestinal tract of a person are affected. The pulmonary form of aspergillosis develops more often. With aspergillus meningitis or encephalitis, death is likely.
The structure of Aspergillus is similar to that of the mold Penicillium. The vegetative body is distinguished in the form of branched mycelium that penetrates the substrate. Conidiophores, consisting of one cell, less often with septa, extend from the supporting cells of the mycelium. On the upper part of the conidiophores, single-celled conidia are located in the form of chains. Mold plaque has the same color as accumulations of mature conidia on the mycelium. After maturation, the conidia break off from the mycelium, are transferred to another place and, under favorable conditions, germinate, giving rise to a new fungal organism. This is the asexual way of reproduction of Aspergillus. Some species reproduce sexually, such as Aspergillus fumigatus.
Aspergillus are active destructive agents of various materials, causative agents of serious diseases and a provoking factor of toxic lesions in animals and humans. These are their negative qualities. But also fungi of this genus are capable of producing various enzymes and other substances during their life activity, which are successfully used in various fields of industry. Thus, Aspergillus niger, a biochemically active fungus, produces many enzymes. In particular, the tanase enzyme is used to form gallic acid, which is used in the production of paints, inks, and some medications. By means of pectolytic enzymes of black aspergillus, wines and juices are clarified and plant stems are split into individual fibers. Aspergillus enzymes make it possible to obtain crystalline glucose from starch, fructose from inulin, and in the course of certain reactions fumaric, oxalic, and citric acids are obtained. With the help of some strains of Aspergillus black, vitamins are synthesized - biotin, B1, B2, the antibacterial drug fumagillin for the treatment of amoebic dysentery, and other medicines. Species A. Orizae and A. Flavus are used in eastern countries to make soy sauce, and in Japan - rice vodka (sake). The beneficial properties of the Aspergillus mushroom are extremely diverse.