Otomycosis - Causes and Pathogenesis

Causes of fungal otitis

According to numerous studies in our climate zone, the main causative agents of otomycosis are considered to be mold fungi6 of the genera Aspergillus and Penicillium and yeast-like fungi of the genus Candida. At the same time, aspergillosis is diagnosed in 65% of cases, penicilliosis - in 10%, candidiasis - in 24%. In some cases, fungal infection of the ear is caused by fungi of the genera Mucor, Altemaria, Geotrichum, Kladosporium, etc. In 15% of cases, a combined infection by fungi of the genera Aspergillus and Candida is detected.

During identification, the following types of mushrooms are identified:

• from the genus Aspergillus: A. niger, A. fumugatus, A. orizae, A. ßavus, A. ochraceus, A. versicolor, A. clavatus, A. glaucus. A. nidulans, A. terreux
• from the genus Penicillium: P. notatum, P. puberulum, P. tardum, P. nidulans, P. chermesinum, P. glaucus, P. chrisogenum, P. citrinum;
• from the genus Candida: C. albicans, C. tropicalis. C. pseudotropicalis, C. krusei. C. glabrata, C. parapsillosis, C. stellatoidea, C. intermedia, C. brumpti, etc.

Pathogenesis of fungal otitis

Basically, the causative agents of otomycosis belong to the group of opportunistic fungi. They cause the disease only under certain conditions that predispose to the development and reproduction of fungi. In this regard, it is important to know about the conditions preceding the disease that could lead to the implementation of the pathogenic properties of fungi. The main pathogenetic moments of otomycosis development: adhesion (attachment of the fungus to the wound surface, to the skin, etc.), colonization of the fungus and its invasive growth,

Various endogenous and exogenous factors are important in the pathogenesis of otomycosis. The cause of adhesion and colonization of the pathogen may be elevated glucose levels in patients with diabetes. In the early stages of this disease, the glucose level in the earwax increases, which promotes the growth of fungi. Endogenous factors predisposing to the development of otomycosis are considered to be somatic diseases. The accompanying general weakening of the body, metabolic disorders, and hypovitaminosis may play a significant role in the development of the disease.

Another important factor in the development of otomycosis is considered to be long-term general and local treatment with antibiotics, the use of glucocorticoids. By suppressing the growth of pathogenic and normal bacterial flora, antibiotics thereby contribute to the development of dysbacteriosis and the activation of fungi. The use of glucocorticoids in large doses leads to a decrease in non-specific and specific immunity. In addition, treatment with cytostatic drugs and radiation therapy can lead to the development of fungal complications.

In the pathogenesis of postoperative otomycosis, the causative factor should primarily be a long-term inflammatory process in the middle ear cavity, accompanied by damage to the epithelium. Inflammatory exudate containing carbohydrates, proteins, peptones, mineral salts and other substances is a good nutrient medium for the pathogen, and constant temperature, high humidity, free access of air to the postoperative middle ear cavity are optimal conditions for the activation and development of fungi. The cause of mycosis of the postoperative middle ear cavity can be ear trauma, including surgery, as well as exposure to non-sterile water. Unfavorable environmental conditions also play a certain role: humidity, dust, industrial contact with antibiotics.

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