Introduction to Medical Mycology

Introduction to Medical Mycology

• Medical mycology is the study of fungi that cause disease in humans.
• Fungi are eukaryotic organisms with a cell wall made up of chitin, β-D-glucan and mannan (in some species).
• Fungi have a cell membrane containing ergosterol, distinguishing them from bacteria.
• Fungi reproduce through budding, or in filamentous fungi, by forming hyphae, that make up a mycelium.
• Fungi can be broadly categorized as molds and yeasts.
• Molds are filamentous fungi, while yeasts are unicellular fungi.
• Some fungi are dimorphic, meaning they can exist as either molds or yeasts depending on the environmental conditions.
• Fungi cause various infections in humans, from superficial ones to systemic ones.

Types of Mycoses

• Superficial mycoses: Affect the outermost layers of the skin (example: Pityriasis versicolor). Frequently caused by skin normal flora.
• Cutaneous mycoses: Affect the skin, hair, and nails (example: Dermatophytosis). Caused by dermatophytes, which are keratin-loving fungi. Different types based on affected zones. Spread by direct or indirect contact.
• Subcutaneous mycoses: Affect the subcutaneous tissue, muscle, and fascia (example: Mycetoma).
• Systemic mycoses: Affect many organ systems (example: Aspergillosis, Cryptococcosis, Mucormycosis, Candidiasis). Occur commonly in immune-compromised individuals.

Mycotoxicosis

• Mycotoxicosis is poisoning by fungal toxins after consuming contaminated food
• Common examples are aflatoxin (produced by Aspergillus flavus) and ochratoxin.
• Aflatoxin causes liver damage and hepatocellular carcinoma (liver cancer).
• Ochratoxin is associated with kidney damage

Q&A

• Q1: Which of these is a component of the cell membrane of fungi?

  • Ergosterol

• Q2: Tinea pedis or ("Athlete's foot") means:

  • Fungal infection of the toe web.