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They reproduce by spreading microscopic spores and then these spores are often present in the air, where they can be inhaled or come into contact with the surfaces of a person's body. Certain types of fungi are normally present on body surfaces or in the intestines. Although normally harmless, these fungi sometimes cause local infections of the skin and nails, vagina, mouth, or sinuses. Although, humans have a high level of innate immunity to fungi these infections are very common.
Most of the infections they cause are mild and self-limiting. The term mycosis refers to conditions in which fungi pass the resistance barriers of the human body and establish infections.
Normal resistance barriers
This resistance is due to:
- The fatty acid content of the skin
- The pH of the skin, mucosal surfaces and body fluids
- Epithelial cell turnover
- Normal flora
- Cilia of the respiratory tract
When fungi do pass the resistance barriers of the human body and establish infections, the infections are classified according to the tissue levels initially colonized.
Risk Factors for Developing Fungal Infections
Use of immunosuppressive drugs
- Anticancer drugs (chemotherapy)
- Corticosteroids and other immunosuppressant drugs
Other diseases and conditions
Lung disease, such as emphysema
Hodgkin's disease or other lymphomas
Types of mycoses
These are infections limited to the outermost layers of the skin and hair. The most common are:
- Pityriasis versicolor
- Tinea nigra
- Black piedra
- White piedra
These infections are restricted to the keratinized layers of the skin, hair, and nails. Unlike the superficial mycoses, host immune responses may be evoked, resulting in pathologic changes expressed in the deeper layers of the skin. The organisms that cause these diseases are called Dermatophytes, and also ringworm or tinea. The following diseases are caused by Microsporum, Trichophyton, and Epidermophyton.
- Tinea capitis
- Tinea corporis
- Tinea manuum
- Tinea cruris
- Tinea pedis
- Tinea unguium
These infections involve the dermis, subcutaneous tissues, muscle, and fascia.
They are often chronic and are initiated by trauma to the skin. They are extremely difficult to treat and may require surgical intervention.
The most common are:
These infections originate primarily in the lungs and may spread too many organ systems. These organisms are inherently virulent.
There represent the infections of patients with immune deficiencies who would otherwise not be infected. Some of those immune deficiencies are AIDS, altered normal flora, diabetes mellitus, immunosuppressive therapy, malignancy etc. They include: