Fungi Flashcards
Differences between fungi and higher eykaroytes
- Ergosterol instead of cholesterol in cell membrane
2. Rigid cell wall
Drug types against ergosterol
- Polyenes (ex amphotericin B)–bind ergosterol
- Azoles (ex keotconazole)–interfere with ergosterol synthesis
- Allylamines (terbinafine aka Lamisil)–interfere with ergosterol synthesis
Which fungi are natural components of human flora?
- Candida albicans
2. Malassezia furfur
Which fungi exist(s) only as yeast?
Cryptococcus
Which fungi exist(s) only as hyphae/mold?
Aspergillus
What are the 2 main morphological forms of fungi?
- Yeast
2. Hyphae/Mycelium (mold)
Blastoconidia
budded cell, asexual
Chlamydoconidia
thick-walled single cells, resistant to adverse conditions
Arthroconidia
single-celled conidia, formed by disjoining of hyphal cells
Conidiospores
Asexual Spores: Macroconidia and Microconidia
Sporangiospores
Asexual Spores, formed at end of hyphae
KOH technique
Diagnostic Lab test: Use KOH on microscrope slide with fungi. KOH digests all non-fungal material (eg human skin cells) so fungi can be seen
Antifungal targets and types
A. Ergosterol
- Polyenes (ex amphotericin B)
- Azoles (ex ketaconazole)
- Allylamides (ex terbinafine)
B. Cell wall synthesis
-Echinocandins (ex caspofungin)
C. Nucleic acid synthesis
-Antimetabolites (ex flucytosine)
D. Disruption of microtubules
-Griseofulvin
Combination therapy
Use drugs from 2 different categories to defeat fungi. Danger of antagonism between different antifungals.
Which deadly fungus so far has no good combination therapy?
Aspergillosis
Resistance to antifungals:
-Primary vs Secondary resistance?
- primary: resistant to drug w/o prior exposure to drug
- secondary: resistance after prior exposure
Normal immune response to fungal infection?
- Innate response
- Adaptive response (Th-1 cells)
No antibody response to fungi
List superficial fungi
- Malassezia furfur
- hortaea (exophiala) weneckii
- piedraia hortae
- trichosporon
List dermatophytes
MET
- Microsporum
- Epidermophyton
- Trichophyton
List subcutaneous fungi
-Sporothrix
- Chromoblastomycosis (not in lecture)
- “spore tricks on thorns” and “chrome robot blasting cauliflowers”
List endemic fungi
- Histoplasma
- Blastoplasma
- Coccidioides
List systemic/opportunisitc fungi
- Candida
- Aspergillus
- Cryptococcus
Malassezia furfur
- superficial
- causes Pityriasis versicolor (bright splotches on skin)
- culture growth requires olive oil
- tx: topical azoles, selenium sulfide shampoo
-‘spaghetti and meatballs’ made at Malassezia’s Italian restaurant, using his amazing olive oil.
Hortaea (Exophiala) werneckii
- superficial
- causes Tinea Nigra (black skin spots)
- tx: topical azoles, topical terbinafine (lamisil)
Piedraia hortae
- superficial, hair
- black piedra (‘stones’) in hair
- tx: topical antifungals, haircut
Trichosporon
- superficial, hair
- white piedra (‘stones’) in hair
- tx: topical antifungals, haircut
Trichophyton
- Dermatophyte
- T. rubrum, T. mentagrophytes
- Causes various tineas.
- ‘ringworm’
“MET”
Epidermophyton
- Dermatophyte
- Causes various tineas.
- ‘ringworm’
“MET”
Microsporum
- Dermatophyte
- M. canis, M. audouinii
- Causes various tineas.
- ‘ringworm’
“MET”
Sporothrix schenckii
- subcutaneous
- gardeners get this from thorn pricks
-“spore tricks on thorns”
List Tineas:
- t. corporis– body
- t. cruris–groin
- t. pedis–foot
- t. capitis–scalp, eyebrows, eyelashes
- t. unguium–nails
- t. barbae–beard
endothrix, ectothrix
- part of Tinea capitis: scalp, eyebrows, eyelashes.
- endo: arthroconidia found inside hair shaft
- ecto: found outside hair shaft
Wood lamp
- diagnostic for tineas.
- some dermatophytes flouresce distinct color when Wood lamp shined on body.
Histoplasma capsulatum
- geography
- symptoms
- source
- diagnostic notes
(Histo)
- mississippi river
- pulmonary infection, disseminate to: pericarditis, fibrosing mediastinitis, blindness
- from soil, bird poop
- resemble TB on x-ray
-Bob Dylan had it, with pericarditis and fibrosing mediastinitis
Blastomyces dermatitidis
- geography
- symptoms
- source
- diagnostic notes
(Blasto)
- mississippi river
- pulmonary infection, disseminate to: skin lesions
- from soil, dogs?
- yeast cell is huge on microscopy
Coccidiodies immitis
- geography
- symptoms
- source
- diagnostic notes
(Cocci, “Valley Fever”)
- SW america
- pulmonary infection, flu-like syndrome, disseminate to: meningitis
- desert soil
- common in AIDS
2 Most common opportunistic fungal infections in immunocompromised
- Candidiasis
2. Aspergillosis
Candida
- Fungal disease type
- morphology
- source
- symptoms
- diagnostic notes
- Systemic/opportunistic
- complex morphology, “pseudohyphae”
- part of normal human flora
- thrush, vaginitis, diaper rash, AIDS
- also common with catheter transfered infections (“candida, catheter”)
Cryptococcus
- Fungal disease type
- morphology
- source
- symptoms
- diagnostic notes
- Systemic/opportunistic
- Always in yeast form (in a big capsule that conceals cell wall ligands to immune response and is too big to be phagocytized)
- pigeon droppings
- pulmonary, dissemates to meningitis
- common and deadly in AIDS
Aspergillus
- Fungal disease type
- morphology
- source
- symptoms
- diagnostic notes
- Systemic/opportunistic
- always in mold form
- found everywhere–dust
- Colonization of lungs forms “Balls” that obstruct bronchi. Invasive Aspergillosis: invades blood and all organs, very deadly.
- Quick diagnosis and aggressive antifungal tx!!
- “ASpire ASpergillus to get ASthma”
Zygomycosis
- Fungal disease type
- list pathogens
- source
- symptoms
- diagnostic notes
- Emerging opportunistic fungal pathogens
- Rhizopus, Mucor, Fusarium
- found everywhere
- pulmonary, then deadly invasion into blood and organs (like Aspergillus)
- “breakthrough” infections because they break through antifungal tx
