Fungal Infection Flashcards
(15 cards)
How many species of fungi exist, and how many of them are considered true pathogens?
There are 250,000 species of fungi, with fewer than 200 being true pathogens.
Name the three types of mycoses and provide examples of the associated pathogenic genera.
Superficial mycoses, cutaneous mycoses (dermatophytosis), and subcutaneous mycoses. Examples include Microsporum, Trichophyton, Epidermophyton, Sporothrix, Conidiobolus, and Basidiobolus spp.
Name the four most important fungal pathogens causing systemic infections.
Histoplasma capsulatum, Coccidioides immitis, Blastomyces dermatitidis, and Paracoccidioides brasiliensis.
Why may fungal virulence factors be more complex than bacterial ones?
Fungal virulence factors may be more complex due to the higher degree of opportunism and the interaction with host status.
What are the three major polysaccharides composing the typical fungal wall?
Mannose, β-1,3, and β-1,6 linked glucans, and chitin.
How does the presence of chitin influence the virulence of Candida albicans?
Chitin mutants in C. albicans are less virulent in rodent models compared to wild-type fungi.
Why is cellular adherence important for fungal infection, and which fungi have identified adhesins?
Cellular adherence is crucial for infection and colonization. Adhesins have been identified in C. albicans and B. dermatitidis.
What is the role of capsules in fungi, and how do they contribute to virulence?
Capsules, like in bacteria, help resist phagocytosis and immune activation. For example, the capsule of C. neoformans inhibits leukocyte accumulation and cytokine secretion.
How do fungi induce apoptosis, and what is an example of a fungal toxin with immunosuppressive qualities?
Fungi induce apoptosis either directly through fungal toxins or secondary to host cell cytoskeleton rearrangements. An example is the gliotoxin of A. fumigatus (induces apoptosis in macrophages).
What role do eicosanoids play in fungal colonization, and which fungi demonstrate their production?
Eicosanoids enhance fungal colonization, and recent evidence shows their production by both dermatophytosis and systemic fungi.
What is the significance of secreted aspartyl proteinase (SAP) genes in Candida spp.?
SAP genes allow persistent colonization of host surfaces and deeper penetration.
What are fungal capsules made of?
Polysaccharides
Which genes in Candida spp. allow persistent colonisation and deeper penetration of host surfaces?
Secreted aspartyl proteinase (SAP)
Give 3 functions of the A. fumigatus gliotoxin.
- Causes DNA fragmentation and apoptosis in macrophages.
- Inhibits neutrophil respiratory burst.
- Inhibits T cell activation.
