Fungal Virulence Factors

1. Adhesion,

2. Temperature tolerance

3. Enzymes such as keratinases which degrade keratin

4. Manipulation of the immune system

5. Irritants and toxins.

Fungal invasion usually go like this:

Defense Systems:

There are nonspecific defenses such as anatomical barriers and physiological factors. There are also specific defenses from the immune system. Cell-mediated response is important in fighting fungal infections which is why AIDS patients get a lot of fungal diseases. Neutrophils are important against systemic fungal infections, so you will see AIDS patients with local fungal diseases and leukemia patients with systemic ones.

Predisposing factors  age, stress, pregnancy, sex, nutritional status, immunosuppressed patients, defective phagocytosis, neutropenia, endocrine disorders, diabetes, cancer, bacterial or viral infections, burns, trauma, occupational exposure, prosthesis, radiation, certain drugs and surgery.

Certain types of immunocompromised conditions are more important to remember in association with fungal infections:

• Leukopenia (bone transplantation)  Candida, Aspergillus,
• Cellular immunity (tissue transplants):  Candida, Cryptococcus,
• Diabetes: Zygomycetes,
• Steroid therapy: Zygomycetes,
• Malignancy (leukemia, lymphoma): Candida, Cryptococcus, Aspergillus,
• AIDS: Candida, Cryptococcus, Histoplasma.

Diagnosis:

Complaint  physician gets samples  confirmatory step such as labs demonstrating the organism isolated in a culture or immunodiagnosis or PCR.

Category: Microbiology Notes