Fungus - Medical Overview

Question 1

MYCOSES Classification

Answer 1

MYCOSES
– Systemic mycoses caused by pathogenic fungi
• Histoplasmosis
• Blastomycosis
• Coccidioidomycosis
• Paracoccidioidomycosis
– Systemic mycoses caused by opportunistic fungi
• Pneumocys pneumonia
• Candidiasis
• Aspergillosis
• Cryptococcosis
• Zygomycosis
– Superficial, cutaneous and subcutaneous mycoses
• Dermatophytoses
• Malassezia
• Chromoblastomycosis
• Phaeohyphomycosis
• Mycetomas
• Sporotrichosis

Question 2

Medical Mycology

Answer 2

• Most mycoses are amont the most difficult diseases to diagnose and treat
  + Sign of mycoses are often missed or misinterpreted
  + Antifungal agents are toxic to humans

Question 3

Epidemiology of Mycoses

Answer 3

• Everywhere in the environment
• Via inhalation, trauma or ingestion
• Most mycoses are NOT CONTAGIOUS
  + FDermatophytes are the major exception and are transmitted via formites
  + Some species of Candida and Pneumocystis can be transmitted by contact
  Epidemics due to mass exposure to environmental source of fungi

Question 4

Clinical Manifestations

Answer 4

3 Categories
- Fungal Infections
+ Most common mycoses
+ Caused by presence of true pathogens or opportunists
- Toxicoses
+ Acquired through ingestion
+ Occur when poisonous mushrooms are eaten
- Allergies
+ Most often result from the inhalation of fungal spores

Question 5

Diagnosis of Fungal Infections

Answer 5

1- Patient history
2- Moprhological analysis of the fungus involved::
- Sabouraud Dextrose agar used to culture fungi
3) Various Techniques to detect fungal cells in patient specimens
- Potassium hydroxide preparation (BLUE)
- Gomori methenamine silver stain
- Direct immunoflourescence (GREEN)
4) Opportunistic infections are especially challenging
5) Symptoms and imaging resembles tuberculosis or cancer

Question 6

Antifungal Therapies

Answer 6

1) Most difficult to heal
- resistant towards T cell-Mediated immune responses
- Biochemically similar to human cells
+ Ergosteril is often the target
2) Amphotericin B
- GOld standard of antigungals
- One of the more toxic antifunga agents
3) Azole drugs:
- Less toxic alternatives drugs
- Ketoconazole, Itraconazolre and Fluconazole
4) Non Ergosteroll antfungal drugs:
- Griseofulvin
+Interferes with microtubule formation and mitosis.
+ Accumulates on the outer layers of hte skin, not toxic, 1year
- 5-fluorocytosine
+ Nucleoside analog, inhibits DNA and RNA synthesis
- Echinocandins
+ Inhibits the synthesis of glucan that makes up part of the fungal cell wall : Osmotic lysis
5) Opprotunistic infections require 2-step treatment
- High dose treatment to reduce pathogens
- Low Dose Maintenace therapy (life long)
- resistance is a rare event

Question 7

Antifungal Vaccines

Answer 7

1) Difficult to develop
- fungal metabolism similar to our own
2) Developed vaccines againsts:
- Coccidioides
- Blastomycosis
- Candida

Question 8

Antifungal Therapies

Amphotericin B

Answer 8

Amphotericin B

• GOld standard of antigungals
• One of the more toxic antifunga agents

Question 9

Antifungal Therapies

Azole drugs:

Answer 9

Azole drugs:

• Less toxic alternatives drugs
• Ketoconazole, Itraconazolre and Fluconazole

Question 10

Antifungal Therapies

Non Ergosteroll antfungal drugs

Answer 10

Non Ergosteroll antfungal drugs:
- Griseofulvin
+Interferes with microtubule formation and mitosis.
+ Accumulates on the outer layers of hte skin, not toxic, 1year
- 5-fluorocytosine
+ Nucleoside analog, inhibits DNA and RNA synthesis
- Echinocandins
+ Inhibits the synthesis of glucan that makes up part of the fungal cell wall : Osmotic lysis

Question 11

Opprotunistic infections require 2-step treatment

Answer 11

Opprotunistic infections require 2-step treatment

• High dose treatment to reduce pathogens
• Low Dose Maintenace therapy (life long)
• resistance is a rare event