DD- Fungal Infections/Rx Flashcards Preview

BL/DD USMLE and Basics > DD- Fungal Infections/Rx > Flashcards

Flashcards in DD- Fungal Infections/Rx Deck (16):
1

Factors that allow overgrowth of opportunistic organisms

Alteration in oral flora
Immunosuppression
Systemic diseases

2

Binds ergosterol in fungal membrane
opens pores
leakage of cellular constituents
cell death [fungicidal]

Amphotericin B - Mechanism of Action

3

Similar mechanism to Amphotericin B - toxicity limits systemic use

No appreciable absorption from GI tract

Safe and effective for topical treatment of candidal infections of skin, mucous membranes, and GI tract

Nystatin

4

-Myelosuppression with chemotherapy agents
-Long-term use of steroid anti-inflammatory agents
-Inhaled steroids use in asthma

Can cause immunosupression

5

Deep candidiasis

Aspergillosis

Mucormycosis

Cryptococcosis

Extracutaneous sporotrichosis

life-threatening systemic fungal infections (esp. in immunosuppressed patients)

6

Inhibits the synthesis of β (1,3)-D-glucan - essential component of fungal cell walls. disruption of cell wall

Higher level of selective toxicity due to absence of these enzymes in mammalian cells

Echinocandins - Micafungin

7

Drug of choice for nearly all life-threatening systemic fungal infections (esp. in immunosuppressed patients)

Amphotericin B - Clinical Uses

8

-AIDS, diabetes
-Long-term xerostomia (anticholinergic agents)
-Adrenal suppression (steroid anti-inflammatory agents)
-Anemia

Systemic diseases examples

9

Selective inhibition of fungal cytochrome P450 (14α-demethylase)  ↓ ergosterol synthesis  fungistatic-cidal

Greater selectivity for fungal vs mammalian cytochrome

Triazoles
Fluconazole - Itraconazole

10

Inhibits P450-dependent enzyme (14α-demethylase) resulting in decreased levels of ergosterol

Disruption in synthesis of cell membrane sterols, alterations in membrane permeability

Fungistatic / fungicidal depending on concentration

Imidazoles
Ketoconazole - Clotrimazole - Miconazole

11

Inhibits squalene oxidase, dec ergosterol synthesis (plus accumulation of squalene is toxic), fungicidal

Concentrates in keratin (like griseofulvin)

Terbinafine

12

Converted in fungal cell into 5-fluorouracil (via cytosine deaminase)

5-FU interferes with DNA synthesis, cell death

High selective toxicity - host cells lack deaminase

Resistance occurs in fungi that lack cytosine deaminase
 

Flucytosine

13

Binds to microtubules inhibiting fungal mitosis - interferes with processing of new cell wall components - fungistatic

Griseofulvin

14

Inhibits protein and nucleic acid synthesis

Effective against wide variety of protozoa (concentrated in organisms)

Pentamidine

15

Dermatophytes

Infections deeper in the epidermis and its integuments - hair and nails

16

Dermatophytes Rx

Generally conservative with use of topical antifungal agents (clotrimazole, miconazole, terbinafine)