LG6.6 mycology Flashcards
name the cell type for fungi. bacteria
eukaryotic. prokaryotic
do fugi have cell walls? bacteria?
yes both have cell walls.
fungi composed of polysaccarides:chitin glactomannan, and alpha and beta 1-3 glucan.
Bacterial cell walls are composed primarily of PDG
describe fungi cell wall. bacteria
chitin. peptidoglycan
describe fugi O2 utilization. bacteria.
both span from aerobic to obligate anaerobes
what’s the doubling time for fungi? bacteria?
hours. minutes
do fungi produce spores? bacteria.
yes, sexual and asexual reproductive spores. bacteria - endospores.
are sterols present in fungi cell membrane? bacteria?
yes - ergosterol. bacteria - sterols absent except mycoplasma
list the 4 risk factors for fungal infections.
- living in warm,humid climate
- occupation
- CMI deficiency
- topical immunosuppression
list 3 types of mycoses
- superficial/cutaneous (most common)
- subcutaneous (rare, tropical climate)
- systemic (deep w/in body (coccidioides). These are endemic in certain geographical regions
list the 3 fungal morphologies
- unicellular yeasts
- multicellular molds
- dimorphic fungi
give some characteristics of yeasts
- unicellular eukaryotes. 2. usually reproduce by budding (buds=blastoconidia) 3. un-detached buds form chains of cells called pseudohypha. 4. colonies bacterial-like
give some characteristics of fungal spores
- used for survival, transmission, reproduction 2. found in soil, vegetation 3. can be IDed based on asexual spores 4.
what is dimorphic fungi and how do they use phenotypic switching?
these are yeasts (or spherule) at 37 degrees C and mold at colder, environmental temps. This affects expression in fungal cell wall components, tricking the host immune system and adding virulence.
List some fungal virulence factors.
- dimorphism 2. adhesions 3. proteases, elastases, phospholipases 4. some resist macrophage killing 5. high alpha 1,3-glucan content 6. siderophores 7. biofilms 8. capsule (only cryptococcus neoformans)
list important factors of microscopic fungal diagnosis:
- best for rapid, cost-effective fungal infection diagnosis 2. must use KOH for fixing/staining. most fungi stain Gr+ 3. difficult to determine morphology 4. can determine if infix is colonization or infect. fungal infections often invade (‘dig’ deeply into) tissue. colonization stays superficial
list some of the important considerations when culturing fungi for diagnosis:
- sample can come from any tissue or fluid. 3. most grow at 25-30 degrees C. typically grow on SDA and SABHI. 4. can add antibiotics to media to SELECT. 5. dimorphic fungi can grow as yeasts at 37 degrees, and molds at 30 degrees 5. yeasts colonies are ‘pasty’ and molds are fuzzy, filamentous.
Can you use DNA to ID fungus?
yes. but molds are usually IDed microscopically. yeasts usually require further testing…can use DNA probes (these are available for major systemic pathogens)
