[W1] Eukaryotic pathogens Flashcards
(38 cards)
What defines fungal cells?
Eukaryotic, chitin cell walls, ergosterol in membranes, osmotrophic, non-photosynthetic.
Name the 5 main fungal phyla.
- Chytridiomycota
- Zygomycota
- Glomeromycota
- Ascomycota
- Basidiomycota
What is dimorphism in fungi?
Ability to switch between yeast and hyphal forms based on environment (e.g., temp, CO₂).
What are the 5 categories of fungal diseases (mycoses)?
- Superficial
- Cutaneous
- Subcutaneous
- Systemic
- Opportunistic
Which fungi commonly cause cutaneous mycoses?
- Trichophyton
- Microsporum
- Epidermophyton
What causes blastomycosis?
Blastomyces dermatitidis – dimorphic, pulmonary to systemic spread.
What fungus causes histoplasmosis?
Histoplasma capsulatum – inhaled from soil/bird droppings.
What is cryptococcosis?
Caused by Cryptococcus neoformans or gattii; CNS involvement common in AIDS.
What causes aspergillosis?
Aspergillus fumigatus – inhaled spores cause pulmonary or invasive infections.
What is candidiasis?
Caused by Candida spp., part of normal flora, overgrowth in immunocompromised.
What is pneumocystis pneumonia (PCP)?
Caused by Pneumocystis jirovecii; cholesterol-based membranes, not ergosterol.
Name 4 major antifungal targets.
- Membrane (ergosterol) – azoles, polyenes, allylamines
- Cell wall – echinocandins, chitin synthase inhibitors
- Nucleic acid synthesis – flucytosine
- Mitosis (microtubules) – griseofulvin
What do azoles do?
Inhibit ergosterol synthesis via 14α-demethylase (e.g., fluconazole).
What are polyenes and their mechanism?
Bind ergosterol, form membrane pores (e.g., amphotericin B, nystatin).
What do echinocandins inhibit?
β-1,3-glucan synthesis in the fungal cell wall.
What is flucytosine’s mechanism?
Converted to 5-FU in fungi → disrupts RNA/DNA synthesis.
List mechanisms of antifungal resistance.
- Drug efflux
- Target modification
- Reduced uptake
- Cholesterol substitution
- HSP90 upregulation
What is a parasite vs. a pathogen?
- Parasite: Lives on/in another and benefits at host’s expense.
- Pathogen: Causes disease.
What causes Acanthamoeba keratitis?
Acanthamoeba spp. – eye infection, mostly contact lens users.
What is Naegleria fowleri?
Thermophilic amoeba causing Primary Amoebic Meningoencephalitis (PAM); usually fatal.
What causes trichomoniasis?
Trichomonas vaginalis – STD, no cyst stage, treated with metronidazole.
What diseases are caused by trypanosomatids?
- Leishmaniasis (Leishmania spp.)
- Sleeping sickness (Trypanosoma brucei)
- Chagas’ disease (Trypanosoma cruzi)
What is a kinetoplast?
A dense mitochondrial DNA-containing granule unique to trypanosomatids.
How is leishmaniasis transmitted?
Sandfly bite; causes cutaneous, mucocutaneous, or visceral disease.
