7. Oral Fungal Infections, Candida Flashcards
- Candidiasis (like most fungal infections) usually results from defects in ___________ and/or lack of _______________.
Defects in normal host defense and/or lack of competitive normal flora
- Fungi are eukaryotes and have similar structures to other eukaryotic cells. This means there are few anti-fungals available to treat fungal infections (due to auto-interactions). One big difference is the cell membrane however. What is that difference?
Fungi cell wall contains ergostal instead of cholesterol. Antifungal strategies have been developed based on the presence of ergostal in the fungal cell wall.
- What are two examples of drug types that we use in anti-fungal therapies?
- Azoles - Inhibit ergosterol synthesis
2. Polyenes - Bind and form pores in ergosterol-containing membranes
- What are the two basic morphologies of fungi?
What does it mean that some fungi are dimorphic?
- Yeasts (single cells)
- Hyphae (filamentous) - multinucleated branched, mold like
Dimorphic - Can exist in both a filamentous or yeast morphology depending on the environmental conditions of growth
- Why is the morphology of Candida albicans described as complicated and fairly unique?
In addition to being referred to as dimorphic, they can assume a psuedohyphae morphology where the cells are elongated and linked like sausages (So Candida is actually polymorphic!)
- In general, healthy people have a sufficient level of innate immunity to fungal diseases. What are the aspects of innate host resistance that contributes to this immunity?
- Intact, functioning epithelium (primary barrier)
2. Fatty acids, pH, epithelial cell turnover, and the normal bacterial flora
- Fungal pathologies
- What is mycotoxicoses?
Poisoning from mycotoxins (toxins from fungi)
- Fungal pathologies
- What are some examples of hypersensitivities that can result from fungi?
- Hay Fever and Asthma (Type 1 hyper.)
2. Contact dermatitis to fungal products (Type 4)
- Fungal pathologies - Where do the following mycoses (fungal infections) occur?
- Superficial mycoses
- Cutaenous mycoses
- Subcutaneous mycoses
- Superficial - Outermost skin layers, hair
- Cutaenous - Skin and nails (tinea capitis at the scalp)
- Subcutaenous mycoses - Fungi/spores introduced via wounds
- Fungal pathologies - What are examples of the following mycoses (fungal infections)?
- Systemic mycoses
- Opportunistic mycoses
- Systemic - Lung infections (inhaled spores) - similar to tuberculosis
- Opportunistic (immunocompromised) - Candidiasis, cryptococcus (bird droppings to lung), aspergillosis (soil to lungs), pneumocystis (lung infection in AIDS)
- What are three reasons as to why opportunistic mycoses are of growing concern?
- Growing use of immunosuppressive therapies (cancer, transplants, autoimmunity)
- Use of broad-spectrum antibiotics
These mycoses should only cause serious disease under unusual circumstances (usually host debilitation)
- What is a fungal disease that is a major problem for immunocompromised hosts?
- Do most humans come into contact with the fungi that cause this disease?
Candidiasis (such as C. albicans)
It is part of the normal flora of many humans (so yes).
- What are predisposing risk factors for candidiasis?
- Being young / infant
- Debilitated (endocrine imbalance, decrease phagocytes, T cell defects, chemotherapy to decrease saliva, steroid therapy (inhalers), antibiotics, HIV)
- Oral appliance (incorrect cleaning)
- Describe normal T-cell mediated (cellular) response to fungal infections
- What is the first chemical released that signals the rest of the immune response?
- The released chemical lead to what three responses?
Th cells respond to fungal antigens by producing cytokines
- The cytokines cause an immune response:
B. Recruit and activate phagocytic cells
C. Stimulate epithelial cell turnover
- Describe the psuedomembrane that can form during a candidiasis infection
- Loosely or firmly attached
- Made of what cells
Loosely attached (contrasts with diptheria, which is hard to remove)
Made of PMNs, dead PMNs, fibrin, and fungal cells