Mycosis (Fungal Infection):

The Term mycosis (plural: mycoses) refers to conditions in which fungi pass the resistance barriers of the human or animal body and establish infections. Mycoses are classified according to the tissue levels initially colonized:

• Superficial mycoses - limited to the outermost layers of the skin and hair.
• Cutaneous mycoses - extend deeper into the epidermis, as well as invasive hair and nail diseases. These diseases 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. The resulting diseases are often called ringworm (even though there is no worm involved) or tinea. Cutaenous mycoses are caused by Microsporum, Trichophyton, and Epidermophyton fungi, which together comprise 41 species.
• Subcutaneous mycoses - involve the dermis, subcutaneous tissues, muscle, and fascia. These infections are chronic and can be initiated by piercing trauma to the skin, which allows the fungi to enter. These infections are difficult to treat and may require surgical interventions such as debridement.
• Systemic mycoses due to primary pathogens - originate primarily in the lungs and may spread to many organ systems. Organisms that cause systemic mycoses are inherently virulent. Generally, primary pathogens that cause systemic mycoses are dimorphic.
• Systemic mycoses due to opportunistic pathogens - infections of patients with immune deficiencies who would otherwise not be infected. Examples of immunocompromised conditions include AIDS, alteration of normal flora by antibiotics, immunosuppressive therapy, and metastatic cancer. Examples of opportunistic mycoses include Candidiasis, Cryptococcosis and Aspergillosis.

Pictured above right: Aspergillosis - Histopathologic image of pulmonary invasive aspergillosis in a patient with interstitial pneumonia. Autopsy material. Grocott's methenamine silver stain. (Click Here for More Information)