Fungi and Mycoses Quiz

Medical Important Fungi

• Fungi are a diverse group of organisms, deriving nourishment from dead organic matter or being parasitic eukaryotic organisms.
• Fungal diseases are categorized based on location of infection.
• Cutaneous mycoses are infections limited to the epidermis, subcutaneous when they penetrate the skin, and systemic when deeply within the body.
• Mycoses can be further divided into true pathogenic and opportunistic fungi.
• Fungi can be unicellular or multicellular
• Fungi can be aerobic, or facultatively anaerobic, chemoheterotrophic organisms.

Structure and Classification of Fungi

• Fungi can be seen with naked eye or microscopically.
• Some fungi like mushrooms can be poisonous.
• Molds and yeasts can cause diseases and allergies.

Overview

• Although fungi were previously classified with plants, they are now categorized in their own kingdom- Mycota
• They can live aerobically or facultatively anaerobically.
• They are chemoheterotrophic, consuming organic matter for nourishment.
• Only about 100 of an estimated 200,000 fungal species are pathogenic to humans.
• Few fungal species are responsible for most clinically important fungal infections.

Mycoses

• Human fungal disease are classified by their location within the body.
• Cutaneous mycoses occur in the skin, hair, and nails
• Subcutaneous mycoses infect beneath the skin
• Systemic mycoses disseminate to internal organs.
• Systemic mycoses can be divided into true pathogenic, and opportunistic varieties.

Fungal Growth and Anatomy

• Fungi reproduce sexually, and asexually.
• Fungi can exist in filamentous (molds) and unicellular (yeasts) forms, or dimorphic forms.
• The filamentous form of fungi, called mycelium is composed of threads called hyphae.
• Hyphae can be interrupted by crosswalls (septate) or uninterrupted (coenocytic).
• Densely packed hyphae create a tissue like structure, often seen in mushroom bodies.

Yeast-like Fungi

• Yeast-like fungi are populations of single disconnected, spheroid cells similar to some bacteria.
• Some are 10 times larger than typical bacterial cells
• Reproduction commonly occurs via budding
• Unicellular fungi reproduce symmetrically via fission.
• Budding yeasts divide asymmetrically.

Dimorphic Fungi

• Some fungi can exist as either yeast (unicellular/budding) and mold (multicellular/filamentous) forms depending on environmental conditions, such as temperature or carbon dioxide levels.
• Examples include diseases like Blastomyces dermatiditis and Histoplasma capsulatum

Fungal Life Cycle

• Fungi reproduce sexually and asexually.
• Asexual reproduction involves spores, or conidia, produced on hyphae.
• Sexual reproduction occurs through processes like meiosis and karyogamy where cells fuse to form new genetic combinations.

Cutaneous Mycoses

• Cutaneous mycoses are caused by dermatophytes (fungi)
• Dermatophytes are grouped into three genera: Trichophyton, Epidermophyton, and Microsporum, each of which have many species.
• Some infections are classified based on infected area:
  • Tinea versicolor (pityriasis versicolor)
  • Tinea nigra
  • Tinea pedis (athlete's foot)
  • Tinea corporis (ringworm)
  • Tinea capitis (scalp ringworm)
  • Tinea cruris ("jock itch")
  • Tinea unguium (onychomycosis)

Subcutaneous Mycoses

• Subcutaneous mycoses are fungal infections of the dermis, subcutaneous tissue, and bone
• Causative organisms reside in soil or decaying vegetation.
• Examples: Sporotrichosis, Chromomycosis, Mycetoma

General Properties of Subcutaneous Mycoses

• Usually acquired through traumatic lacerations, punctures, or thorn pricks.
• Increased prevalence in individuals with frequent contact with soil or vegetation.

Sporotrichosis, Chromomycosis, Mycetoma

• Description of the specific characteristics and symptoms of each infection.

Systemic Mycoses

• Organisms are categorized into true pathogens and opportunistic pathogens.
• Most common examples are coccidioidomycosis, histoplasmosis, and blastomycosis.
• These infections occur in defined geographic regions.

Opportunistic Mycoses

• These infections affect debilitated or immunocompromised patients.
• Immuno-suppressive treatments may increase the risk for opportunistic fungal infections,
• Common opportunistic fungal species are Candida species, Cryptococcus neoformans, Aspergillus, and Pneumocystis jiroveci.

Candidiasis (Candidosis)

• Caused by the yeast Candida albicans and other species.
• Common in mucous membranes, including the mouth, skin, vagina and intestines.
• Demonstrates dimorphism, capable of forming a true mycelium.

Cryptococcosis

• Caused by the yeast Cryptococcus neoformans
• Often found in soil with bird dropping.
• Common complication is meningitis

Aspergillosis

• Caused by the species Aspergillus fumigatus
• Primarily affects immunocompromised patients
• Can infect the lungs.

Pneumocystis jiroveci

• Caused by the yeast-like fungus Pneumocystis jiroveci.
• A type of pneumonia.

Nosocomial Infections

• Fungal nosocomial infections are approximately 15% of all hospital acquired infections, and are common in intensive care units.
• Frequently encountered opportunistic species include Candida species.

References

• Citations for text-based reference sources.

Test your knowledge on fungi and mycoses with this engaging quiz. Explore various aspects including the characteristics of fungi, types of mycoses, and the pathogenic effects of these organisms. Perfect for students studying microbiology or for anyone interested in the fascinating world of fungi.