Introduction to Medical Mycology I & II

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Questions and Answers

What is the primary mode of transmission for dermatophyte infections?

Inhalation of spores

Ingestion of contaminated water

Direct and indirect contact (correct)

Vector-borne transmission

Which of the following conditions is NOT a clinical lesion of dermatophytosis?

Tinea unguium

Tinea cruris

Tinea capitis

Psoriasis (correct)

Tinea barbae primarily affects which area of the body?

Scalp

Beard and mustache (correct)

Toe web

Groin

What type of mycosis is characterized by infections in immunocompromised individuals?

Opportunistic mycosis Signup and view all the answers

Which type of mycosis affects subcutaneous tissue and muscle?

Subcutaneous mycosis Signup and view all the answers

Cryptococcosis is most commonly associated with which type of patient?

HIV patients Signup and view all the answers

Which of the following is a common symptom of candidiasis?

Skin lesions Signup and view all the answers

Which fungal toxin is primarily associated with liver damage?

Aflatoxin Signup and view all the answers

Tinea pedis is commonly known as?

Athlete's foot Signup and view all the answers

Which species is NOT classified under dermatophytes?

Aspergillus Signup and view all the answers

What component is present in the cell wall of fungi?

Chitin Signup and view all the answers

Which of the following best describes dimorphic fungi?

Fungi that can switch between yeast and mould forms. Signup and view all the answers

Which type of fungi causes superficial mycosis?

Malassezia spp. Signup and view all the answers

Which of the following statements about moulds is correct?

They exist in branching filamentous forms called hyphae. Signup and view all the answers

What distinguishes opportunistic fungi from primary pathogenic fungi?

Opportunistic fungi only infect immunocompromised individuals. Signup and view all the answers

How do yeasts primarily reproduce?

Budding Signup and view all the answers

Which fungus is an example of a septated mould?

Penicillium Signup and view all the answers

What is the main characteristic of cutaneous mycosis?

It involves the hair and nails in addition to the skin. Signup and view all the answers

What structural component is found in the cell membrane of fungi?

Ergosterol Signup and view all the answers

Which of these fungi primarily causes dermatophytosis?

Dermatophytes Signup and view all the answers

Study Notes

Introduction to Medical Mycology (I & II)

Medical mycology is the study of fungi and their diseases in humans.
Fungi are eukaryotic organisms with true nuclei and nuclear membranes.
Fungi have rigid cell walls containing chitin, β-D-glucan, mannan, and galactomannan.
The cell membrane of fungi contains ergosterol.
Fungi have cytoplasms containing the nucleus, ribosomes, and mitochondria.

Morphology of Fungi

Moulds (Filamentous Fungi):
- Filamentous, branching structures called hyphae.
- Septate (divided by cross walls) or non-septate.
- Mass of hyphae forms mycelium.
- Examples: Aspergillus spp., Penicillium, Mucor.
Yeasts:
- Unicellular, rounded or oval in shape.
- Reproduce by budding.
- Budding cells can separate from the mother cell, or stay attached to form pseudohyphae
- Examples: Cryptococcus neoformans, Malassezia, Candida.
Dimorphic Fungi:
- Grow as yeast during infection at 37°C (body temperature)
- Grow as mould at room temperature (25°C). -Example: Histoplasma capsulatum.

Classification of Medically Important Fungi

Primary Pathogenic Fungi (Endemic Mycosis):
- Cause disease in immunocompetent individuals.
- Examples: Dimorphic fungi like Histoplasma capsulatum.
Opportunistic Fungi:
- Cause disease in immunocompromised individuals.
- Examples: Candida.

Human Mycoses

Mycosis: Disease caused by fungi.
Types of Mycosis:
- Superficial Mycosis: Infection of the outermost skin layers.
  - Example: Pityriasis versicolor (caused by Malassezia spp.)
- Cutaneous Mycosis: Infection extending deeper into dermis, hair, and nails.
  - Example: Dermatophytosis (Tinea), caused by Dermatophytes (e.g., Trichophyton, Microsporum, Epidermophyton)
  - Various forms of tinea (e.g., tinea capitis, tinea barbae, tinea corporis, tinea pedis, tinea cruris, tinea unguium).
- Subcutaneous Mycosis: Infection of subcutaneous tissues, muscle, and fascia.
  - Example: Mycetoma.
- Systemic Mycosis: Infection affecting multiple organ systems.
  - Examples of opportunistic mycoses include Aspergillosis, Cryptococcosis, Mucormycosis, and Candidiasis (Candida albicans and non-albicans species).
- Mycotoxicosis: Poisoning from ingestion of food contaminated with fungal toxins. - Examples: Aflatoxin (produced by Aspergillus flavus, linked to liver damage and cancer), Ochratoxin (produced by Aspergillus or Penicillium, linked to kidney damage).

Important Questions

Q1: Ergosterol is a component of fungal cell membranes.
Q2: Tinea pedis ("Athlete's foot") is a fungal infection of the toe web and sole.

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Description

Explore the fascinating world of medical mycology, focusing on fungi and the diseases they cause in humans. This quiz covers the basic morphology of fungi, including moulds, yeasts, and dimorphic fungi, alongside their cellular structures and reproductive methods.