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Otomycosis: causes and pathogenesis
Last reviewed: 23.04.2024
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Causes of fungal otitis
According to numerous studies in our climatic zone, the main pathogens of otomycosis are mold fungi6 of the genera Aspergillus and Penicillium and yeast-like fungi of the genus Candida. In this case, aslergillol is diagnosed in 65% of cases, penicilliosis - in 10%, candidiasis - in 24%. In some cases, fungal damage to the ear causes fungi of the genera Mucor, Altemaria, Geotrichum, Kladosporium, etc. In 15% of cases, the combined fungus of the genera Aspergillus and Candida is identified.
Identification of the following species of fungi:
- from the genus Aspergillus: A. Niger, A. Fumugatus, A. Orizae, A.ßavus, A. Ochraceus, A. Versicolor, A. Clavatus, A. Glaucus. A. Nidulans, A. Terreux
- of the genus Penicillium: P. Notatum, P. Puberulum, P. Tardum, P. Nidulans, P. Chermesinum, P. Glaucus, P. Chrisogenum, P. Citrinum;
- of the genus Candida: C. Albicans, C. Tropicalis. C. Pseudotropicalis, S. Krusei. C. Glabrata, C. Parapsillosis, C. Stellatoidea, C. Intermedia, C. Brumpti and others.
Pathogenesis of fungal otitis
Most pathogens of otomycosis are classified as a group of conditionally pathogenic fungi. They cause the disease only under certain conditions, predisposing to the development and reproduction of fungi. In this regard, it is important to know about the conditions preceding the disease, which could lead to the realization of the pathogenic properties of fungi. The main pathogenetic moments of development of otomycosis: adhesion (attachment of the fungus to the wound surface, to the skin, etc.), colonization of the fungus and its invasive growth,
In the pathogenesis of otomycosis, various endogenous and exogenous factors are important. The cause of adhesion and colonization of the pathogen may be an increased level of glucose in patients with diabetes mellitus. In the early stages of this disease, the level of glucose in the ear wax increases, which promotes the growth of fungi. Endogenous factors predisposing to the onset of otomycosis are considered somatic diseases. Concomitant general weakening of the body, metabolic disorders, hypovitaminosis can play a significant role in the onset of the disease.
Another important factor in the development of otomycosis is the long-term general and local treatment with antibiotics, the use of glucocorticoids. Suppressing the growth of pathogenic and normal bacterial flora, antibiotics thus contribute to the development of dysbiosis and activation of fungi. The use of glucocorticoids in large doses leads to a decrease in nonspecific and specific immunity. In addition, the emergence of fungal complications may result in cytostatic medications and radiation therapy.
In the pathogenesis of postoperative otomycosis, the long-term inflammatory process in the cavity of the middle ear, accompanied by damage to the epithelium, is the primary causative factor. Inflammatory exudate containing carbohydrates, proteins, peptones, mineral salts and other substances is a good nutrient medium for the pathogen, and the constant temperature, high humidity, free air access to the postoperative cavity of the middle ear are the optimal conditions for the activation and development of fungi. The cause of mycosis of the postoperative cavity of the middle ear can be a trauma to the ear, including the ear, as well as the ingestion of non-sterile water. A certain role is played also by unfavorable environmental conditions: humidity, dustiness, industrial contact with antibiotics.
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