Fungal pathogenesis Flashcards
(31 cards)
Where are fungi commonly distributed?
In air, dust, fomites, and normal flora (commensals)
Are most fungi pathogenic to animals and humans?
No, few fungi are linked to disease in animals and humans.
Why are humans and animals relatively resistant to fungal infections?
Because of their high body temperature.
What type of organisms are fungi most commonly pathogenic to?
Plants.
What is a mycosis?
A fungal infection.
What causes mycoses?
True fungal pathogens causing primary infections and opportunistic fungal pathogens causing secondary infections.
What are the three categories of mycoses?
Cutaneous/superficial, subcutaneous, and systemic.
Why can’t cutaneous fungi survive inside the body?
Because they grow at room temperature and cannot survive body temperature.
What is mycotoxicosis?
Disease caused by intake of fungal toxins.
What produces mycotoxins?
filamentous fungi.
Name a mycotoxin and its producing fungus.
Aflatoxin produced by Aspergillus species.
Are most fungal infections communicable?
What 2 species are?
No, except for Dermatophytes and Candida species.
What are primary fungal pathogens?
Fungi that can invade and grow in a healthy, non-compromised host.
What are common host susceptibility factors for fungal infections?
Breakdown of physical barriers, suppression of CMI, hormonal changes.
How does progesterone affect susceptibility to candidiasis?
Increased progesterone levels increase susceptibility.
What are opportunistic fungal infections?
Infections that occur in debilitated or immune-compromised hosts.
Name fungi that are environmental reservoirs and opportunists.
Cryptococcus and Aspergillus.
What are predisposing factors for opportunistic fungal infections?
Antibiotic therapy, corticosteroids, diabetes, catheters.
What are the portals of entry for fungi?
Inhalation, skin damage, ingestion.
How do fungi invade cutaneous tissues?
Spores contaminate skin or hair follicles and germinate, hyphae penetrate skin.
What causes lymphocutaneous sporotrichosis?
Sporothrix schenckii through contaminated thorns or wood.
How do systemic fungal infections develop?
Fungi erode blood vessels to enter bloodstream after local infection.
What are common virulence factors of fungi?
1) ability to adhere to host by cell wall glycoproteins & capsules resist phagocytosis
(2) secretion of enzymes
3) ability to grow at higher temp (fever range)
4) ability to exhibit thermal dimorphism
= improves chances of survival in warm-blooded
How do fungi adhere to host cells?
Using cell wall glycoproteins and capsules.
