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Aspergillus
Last reviewed: 23.04.2024
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Aspergillosis is caused by mold fungi of the genus Aspergillus.
Read also: Allergic bronchopulmonary aspergillosis: causes, symptoms, diagnosis, treatment
[Morphology and physiology of aspergillus
Aspergillas are represented by a septate branching mycelium. They reproduce mainly asexually, forming conidia black, green, yellow or white. Conidia depart from one or two rows of cells - steri, which are on the swelling of the spine-bearing hyphae. Being strict aerobes, they grow on the medium of Saburo, Czapek and wort agar at 24-37 ° C. After 2-4 days on dense media white fluffy colonies grow with the subsequent additional coloring,
Pathogenesis and symptoms of aspergillosis
In patients developing: invasive pulmonary aspergillosis (usually caused by A. Fumigatus) with rapid aspergillus growth and vascular thrombosis, allergic bronchopulmonary aspergillosis in the form of asthma with eosinophilia and allergic alveolitis, aspergilloma (aspergillus asthma) - a granuloma, usually lung, in the form of a ball of mycelium Surrounded by a dense fibrous wall. In immunodeficiency, disseminated aspergillosis with lesions of the skin, CNS, endocardium, nasal cavity, paranasal sinuses is noted .
Pathogenicity factors of aspergillus
Factors of pathogenicity of fungi are acid phosphatase, collagenase, protease, elastase. Aspergillus toxins, for example aflatoxins, are responsible for aflatoxicosis, food ethanol poisoning associated with the accumulation of A. Parasiticus aflatoxins in food. Aflatoxins cause cirrhosis of the liver, have a carcinogenic effect. In protection against the fungus, granulocytes and macrophages, digesting horses, participate. Developed HRT.
Epidemiology of Aspergillosis
Aspergillas are found in soil, water, air and rotting plants. Of the 200 Aspergillus species studied, about 20 species (A. Fumigatus, A. Flavus, A. Niger, A. Ferreus, A. Nidulam, etc.) cause disease in a person with weakened immunity. Aspergillus is transmitted by inhalation of conidia, less often by contact. They get into the lungs when working with moldy papers, dust (disease of junkies, garbage collectors). Infection is facilitated by invasive methods of treatment and examination of patients (puncture, bronchoscopy, catheterization).
Microbiological diagnosis of aspergillosis
Material for the duration of the study is the skin, nails, cornea, separated sinuses of the nose, external auditory canal, sputum, pus, feces, tissue biopsy. In smears (stained with 1 frame, hematoxylin and eosin, according to Pan-Gizon), septate mycelium, chains of conidia are detected. Separate lumps of sputum are transferred to a drop of alcohol with glycerin or in a drop of 10% KOH and after pressing the cover slip and copied. It is possible to cultivate the pathogen on nutrient media. You can put a skin-allergic test, serological reactions (RSK, RP, ELISA, RIA), analysis for aspergillosis: antibodies to the causative agent of aspergillosis in the blood and PCR.