Wk16D1 Fungi Basics Flashcards Preview

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Flashcards in Wk16D1 Fungi Basics Deck (23):
1

8 Virulence factors

Cell wall, capsules, proteases, lipases, toxins, melanin, adhesins, biofilms

2

Fungal plasma membrane and cell wall components.

Plasma membrane contains ergosterol.
Cell wall contains chitin (polysaccharide), other polysaccharides (B-glucan), and other density-based layersd

3

What is clinical significance of ergosterol?

Not found in mammalian cells, so a drug target.
Ergosterol synthesis or in membrane

4

Lab test method for identifying Candida albicans and Cryptococcus neoformans

Candida albicans = + germ tube test
Cryptococcus neoformans - India stain (negative stain)

5

Lab methods to diagnose cryptococcal meningitis (as well as therapeutic monitoring)

Culture of spinal fluid or sputum. India ink, latex bead agglutination, CSF titer decreases w/ effective therapy. Fontana Masson stain (melanin)

6

How does morphology of Blastomyces dermatitidis and HIstoplasma capsulatum differ as they appear in host and environment?

In general, dimorphic are moulds @ 28-30C and yeast @ 37 (except coccidiodes = spherules)

7

Polyenes MOA, Resistance, Example
ON SUMMATIVE!!!

Bind ergosterol, disrupting membrane
Ergosterol downregulation/ replacement/ reorientation
AmB IV, Nystatin oral/topical

8

Azoles MOA, Example
ON SUMMATIVE!!!

Inhibit C. P450 demethylation of ianosterol (ergo synth)
Imidazoles (ketoconazole) and triazoles (IVF, itra/vori/flu)

9

Echinocandins MOA, Resistance, Example

Noncompetitively inhibit B1,3-glucan synthase (cell wall)
Target mod/downreg
-fungins (capso/mica/anidula)
Use for candidiasis

10

Allyamines MOA, Resistance, Example

Inhibit squalene epoxidase (ergo synth, squalene accumulation)
Target mod/upregulation, penetration
-fines (nafti/terbina[oral])...H-PHOBIC
Used in dermatophytosis

11

5-fluorocysteine MOA, Resistance

Nucleic acid synth
Rapid resistance
Limited spectrum of activity

12

What are yeasts? How do yeasts reproduce?

Unicellular and round
mitosis: budding or fission

13

What are moulds? How do moulds reproduce?

Multicellular and filamentous, hyphae+septa
Use spores + conidia

14

What's are the 2 main forms of fungi? What is an example of an alternative form?

Yeasts, Moulds
(Spherules: Coccidiodes)

15

Manifestations of Candidiasis and Ecology

Mostly Candida albicans. Yeast infection, thrush, but can infect all organs.
Found in most people in GI/GU tracts. Birth canal, dentures, Abx, immunosuppression, pregnancy

16

Is Candidiasis contagious? Who gets Candidiasis?

Not usually though it can be found in environment. Typically etiology is from individuals flora.
Patients with neutropenia, diminished phagocytosis, diminished cell mediated immunity (mucocutaneous involvement)
PSEUDOPHYPHAE
String of pearls in retina

17

What is a mucocutaneous area? What might it indicate?

Where mucus becomes skin (lips, nostril, conjunctiva, vagin, urethra, anus)...candidiasis there indicative of cell-mediated immunity aka CD4 defect.

18

Kneejerk reaction: PIGEON Droppings
Organisms
Diseases
Also, EUCALYPTUS
Diagnosis

CRYPTOCOCCOSIS!!! C. neoformans/gattii/grubbii with HUGE galactoxylomannan capsule (negative immunomodulator, negative stain)
Pneumonia (may evade xray)
Meningitis (esp. in collagen disease patients)
Not dimorphic
Eucalyptus - gattii, immuno-competent peeps
CrAg from CSF

19

Histoplasmosis

Intracellular (HISTiOcytes!), Tornado Alley area, often in AIDS patients. Pigeon, Bird/bat droppings. Mimics TB.
Treatment: liposomal amphotericin B, Itraconazole
Fistula
Urine ag test
Coin lesion

20

Blastomycosis

Wider, norther Tornado alley. Mimic TB w/ SKIN+bone lesions. Yeast has broad base bud. DOGS and BEAVER DAM (wet wood). Hyphae pair-shaped

21

Coccidioidomycosis

SW USA and below. C. immitis/posadasii. Filipinos. Filament in environment. Coccidiodin skin test. Desert bumps/rheumatism.
Treat with triazoles then amphotericin B
Meningitis: lifelong fluconazole

22

Aspergillosis

Worldwide
Organ transplants, burns, foreign bodies
Angioinvasive hyphae V shaped branches
Diagnose w/ Galactomannan or Beta-D-glucan
Only mold, forms moving fungus ball
ABPA mimics asthma

23

Uncontrolled Diabestes

Mucor and Rhizopus
Hyphae at right angles