Question

Medical Microbiology Tutorial: Fungal Infections

Answer 1

\({\bf{Definitions:}}\)
fungi: a classification given to eukaryotic heterotrophs that gain nutrients by producing extracellular enzymes and digesting (often dead) material. also characterized by sexual and asexual reproductive cycles.
model organism: for fungi, this is Sacchromyces cerevisiae (baker's yeast)
yeast: unicellular, budding form of fungi
mold: multicellular, filamented form of fungi
> hyphae: filaments present in mold
> mycellium: aggregate of all hyphae in a mold
dimorphic species: species capable of both mold and yeast-like growth. typically take mold form in the environment and yeast form in host.
fruiting body/sporophore: part of the fungus that is visible and makes spores for reproduction

Answer 2

\({\bf{Cell~Wall:}}\)

components:
- mannoproteins: glycoproteins made of mannose polymer + protein
- glucans: glucose-derived polysaccharides. possible virulence factor.
- chitin: glucose-derived polysaccharides that give structure

\({\bf{Reproduction:}}\)
Asexual Reproduction: mycellium produces haploid spores that mature into haploid mycellium. alternatively, budding or fragmentation.

Sexual Reproduction: haploid mycellium fuse to make diploid zygote. undergoes meiosis to make more spores.



\({\bf{Classification:}}\)
1. yeasts
2. yeast-like
3. filamentous
4. dimorphic
5. atypical

will cover all five types at least briefly and try to give an infectious example of each

Answer 3

\({\bf{Superficial~vs~Deep~Mycoses:}}\)
Superficial: typically limited to the cutaneous, and doesn't cause serious inflammatory responses
Three sub-types
1. skin (dermatophytosis)
2. nails (onychomycosis)
3. mucosal (superficial candidiasis)

Deep:
Three sub-types
1. deep/viscal candidiasis
2. Aspergillosis
3. Crytococcosis

\({\bf{Treatments:}}\) are limited in scope because there's just not as much research done on fungal infections, plus they aren't perceived as much of a threat because there's only a handful of fungal species that can do serious harm to people
That being said there are 4 main categories, classified on what they target:

1. azole (targets cell membranes)
2. echinocandins (targets cell wall). low toxicity to people.
3. fluorinated pyrimidines (targets fungal DNA/RNA synthesis)
4. polyenes (targets steroids in cell membranes). high toxicity to people.

Answer 4

\({\bf{Candidiasis:}}\) caused by the yeast-like fungus in the genus Candida
- can cause infections on mouth, throat, esophagus, vaginal reigons
- called "thrush" when it's on mouth/throat areas
- presents as visible white patches, pain/redness, and problems w/ taste or swallowing

Diagnosis
- looking at the visible signs like white patches or redness
- mouth/throat cultures
- endoscopy

Treatments
- antifungals like nyastatin or triamcinolone. can come in various forms like creams or pills.
- IV fluconazole may be used in severe cases

Answer 5

This is getting a little long so I'll make a part 2 for the less common infections

Sources:
- https://biologydictionary.net/fungi/
- https://www.ncbi.nlm.nih.gov/books/NBK7902/
- https://www.ncbi.nlm.nih.gov/books/NBK7902/
- lecture notes