L23: Intro to Medical Mycology Flashcards
Mycotoxins
Toxins that affect humans on some level but don’t really cause disease
Allergens
Cause allergies (many in air)
Fungal cell
Typical eukaryotic cell but has cell walls and membrane sterol composition is ergosterol
Fungal classification
- Yeast
- Mold
Dimorphic = can exist as both
Yeast characteristics
- -Unicellular
- -Reproduce by budding
- -Can form pseudohyphae (one can form a germ tube)
Hyphae
Can group together to form mycelium (vegetative or aerial)
Septa
Hairlike strands of mold that are long tubes
Reproduction of molds
Asexual (prouce conidia, but call them spores anyway) or sexual (produce spores)
Types of fungal infections
- -Superficial mycoses
- -Cutaneous mycoses
- -Subcutaneous mycoses
- -Systemic mycoses
- -Opportunistic mycoses
Superficial mycoses
Infection of the outermost layers of skin and hair
Cutaneous mycoses
Infection which extends into epidermis as well as hair and nails (common ones such as ringworm and athlete’s foot)
Subcutaneous mycoses
Infections involving the dermis, subcutaneous tissues, muscle, and fascia
Systemic mycoses
Infections that originate primarily in the lung but may spread to any organ in the body
Opportunistic mycoses
Infection associated primarily with immunosuppressed individuals
Host response to fungal infection
- -Normally innate immune system is sufficient to prevent fungal infection
- -Traumatic implantation or inhalation can lead to infections
- -Severity depends on size of inoculum, magnitude of tissue destruction, ability to multiply, and immunologic status
- -Cell-mediated immunity is most important
Antifungal drugs
- -Can be topical or systemic
- -Most common targets are cell wall and cell membrane (through direct membrane damage or prevention of ergosterol synthesis)
Polyenes
Bind to membrane sterols to disrupt membrane
What kind of antifungal agents inhibit ergosterol biosynthesis?
Azoles, allylamines, thiocarbamates, and morpholines
Amphotericin B (polyene)
Used to be most widely used antifungal drugs, binds to ergosterol in membrane that causes pore to form
Which types of antifungal drugs affect cell wall synthesis and how do they work?
Echinocandins (inhibits synthesis of B-glucan in cell wall)
KOH prep
KOH dissolves skin cells/human cells faster than fungal cells
All fungi stain ___.
Gram+
India ink stain stains what particular fungi?
Cryptococcus neoformans
Germ tube test is used for what generally?
Candida albicans
