Mycoses And Antifungal Agens

Question 1

What are the two classifications of Mycoses and describe them.

Answer 1

1. Systemic infection (deep)
   -affecting tissues or organs
2. Superficial infection
   - affecting skin, nails, scalp or mucous membranes

Question 2

Describe the fungi cell wall

Answer 2

• protection against mechanical injury
• prevents osmotic lysis
• provides passive protection against internalisation or harmful macromolecules
• composed of chitin

Question 3

Describe a yeast cell

Answer 3

• unicellular organism
• reproduced by budding
• once budding has occurred, a bud scar remains on the cell wall
  Parent cell and bud contains cell wall
• they have 3 membranes: cell, vacuolar and nuclear membrane

Question 4

Describe a mould

Answer 4

• multicellular organisms
• They reproduce asexually by spore formation or by fragmentation
• aerobic organisms
  Can be killed by mild head

Question 5

What are the 3 types of fungal diseases and what so they mean.

Answer 5

1. Allergies (hypersensitivity ti fungal antigens)
2. Mycotoxicoses (consuming/ ingestion of fungal toxins)
3. Mycoses (ingestion invasion of living tissue by fungus)

Question 6

How can fungus be reproduced.

Answer 6

1. Growth and spread of hyphae filaments
2. Asexual reproduction of spores
3. Budding

Question 7

State a SUPERFICIAL fungal disease with the species name.

Answer 7

Pityriasis versicolour
- Mycoses: superficial
Species name: malassezia furfur

Question 8

State a CUTANEOUS fungal disease with the species name.

Answer 8

Athletes foot
- species name: trichophyton rubrum

Question 9

State a SUBCATANEOUS fungal disease with the species name.

Answer 9

Chromoblastomycosis
Species name: fonsecaea pedrosoi

Question 10

State a SYSTEMATIC fungal disease with the species name.

Answer 10

Blastomycosis
Species name: blastomyces dermatitis

Question 11

State a OPPORTUNISTIC fungal disease with the species name.

Answer 11

Candidosis/ candidiasis
Species name: Candida albicans

Question 12

What are the tales of anti fungal therapy

Answer 12

1. Polyenes
2. 5 - flurocytosine
3. Azoles
4. Echinocandins
5. Griseofulvin

Question 13

Antifungal drugs work by what mode of actions.

Answer 13

1. Impairment of cell wall synthesis
2. Impairment of fungal cell membrane
3. Inhibit nuclear acid synthesis
   Inhibit fungal mitosis

Question 14

Inhibit fungal mytosis

Answer 14

• binds to intercellular microtubular protein and inhibits fungal mytosis
  Eg: griseofulvin

Question 15

Impairment of fungal cell membrane

Answer 15

Terbinafine
- fungus affected by accumulation of toxic squalene within its cell

Question 16

Inhibit nuclear acid synthesis

Answer 16

5 - flucytosine
- in fungal cells they are converted into 5 - fluorouracil
- which inhibits both RNA and DNA synthesis

Question 17

Impairment of fungal cell membrane

Answer 17

1. (Azoles anti fungals) imidazole and triazole
   - blocks synthesis of ergosterol and lanosterol
   - inhibits fungal membrane growth
   Tramples have greater selectivity against fungi than imidazoles
2. Newer generation Azoles;
   As effective but Less toxic
   - active against fluconazole resistant invasive Candida and cryptococcus

Question 18

Impairment of fungal cell membrane

Answer 18

1. Polyene macrolide Antibiotics
   - binds to membrane ergosterol in fungal cell
   - alters membrane integrity with ion leakage and fungal cell damage

Eg: amphotericin B and Nystatin