Deep mycoses (deep fungal infections) are fungal diseases that not only affect the skin, mucous membranes, and subcutaneous tissues but also involve deeper tissues and organs, potentially leading to disseminated infections. These infections are also referred to as invasive fungal infections (IFIs). The most common pathogens in deep mycoses include Candida species, Cryptococcus neoformans, and Aspergillus species. In recent years, the incidence of these diseases has been increasing due to factors such as the widespread use of antibiotics, corticosteroids, and immunosuppressants.
Etiology and Pathogenesis
Fungi are broadly categorized into yeasts and molds based on their growth forms. Common pathogenic yeasts associated with human diseases include Candida species and Cryptococcus neoformans, while molds prominently include Aspergillus, Mucor, and dermatophytes. Some fungi, classified as dimorphic fungi, exhibit more than one morphological form in tissue and culture media. Diseases caused by these fungi include histoplasmosis, blastomycosis, sporotrichosis, coccidioidomycosis, and paracoccidioidomycosis.
Fungi do not generally produce toxins. Their pathogenic effects are primarily linked to the physical and chemical damage caused by fungal replication at the infection site within the human body, as well as the production of enzymes and acidic metabolic byproducts. Additionally, certain fungi may trigger hypersensitivity reactions of varying severity. Common pathological changes in fungal infections include:
- Mild, nonspecific inflammation.
- Suppurative inflammation, manifesting as small abscesses formed by infiltration of numerous neutrophils, as seen in candidiasis, aspergillosis, and mucormycosis.
- Necrotizing inflammation, characterized by necrotic lesions of varying sizes, often accompanied by significant hemorrhage and relatively few inflammatory cells, observed in conditions such as mucormycosis and aspergillosis.
- Formation of tuberculoid granulomas.
- Fungal septicemia, where fungi enter the bloodstream, causing disseminated infections and involving multiple organs.
Principles of Treatment
General Therapy
Primary diseases are addressed, and underlying causes are eliminated.
The indications for antibiotics, corticosteroids, and immunosuppressants are carefully controlled, with limited or no use of these medications whenever possible.
Supportive care is provided, including supplementation with vitamins and trace elements.
For skin and oral mucosal infections, nystatin is frequently used. Localized lesions may be treated with surgical intervention where necessary. In cases where allergic symptoms are the main clinical manifestation, antihistamines may be used as symptomatic treatment. For cryptococcal meningitis, in addition to antifungal therapy, measures to reduce intracranial pressure are required, which may include ventricular drainage if necessary.
Antifungal Therapy
Antifungal agents are selected based on the specific pathogen involved. Common antifungal drugs include amphotericin B, flucytosine (5-FC), fluconazole, voriconazole, itraconazole, posaconazole, caspofungin, micafungin, and nystatin.