Fungi and Mycoses Quiz

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Questions and Answers

What is the kingdom to which fungi are assigned?

Protista

Animalia

Mycota (correct)

Plantae

Which type of mycosis is limited to the epidermis?

Opportunistic mycosis

Systemic mycosis

Subcutaneous mycosis

Cutaneous mycosis (correct)

Which of the following characteristics differentiates fungi from plants?

Absence of chlorophyll (correct)

Eukaryotic cellular structure

Presence of chlorophyll

Ability to reproduce sexually

What are the two basic morphologic forms of most fungi?

Filamentous and yeast Signup and view all the answers

Which of the following statements about fungal spores is correct?

They contribute to human allergies. Signup and view all the answers

What distinguishes true pathogenic mycoses from opportunistic mycoses?

The host's immune status Signup and view all the answers

What type of fungi can switch between filamentous and unicellular forms?

Dimorphic fungi Signup and view all the answers

What is one way fungi can cause harm to humans other than infection?

Causing poisoning Signup and view all the answers

What structure do hyphae form when they are densely packed?

Mycelium Signup and view all the answers

Which characteristic distinguishes septate hyphae from nonseptate hyphae?

Presence of crosswalls Signup and view all the answers

What are 'true' pathogens responsible for systemic mycoses known to do?

Infect normal healthy individuals Signup and view all the answers

Which of the following is NOT commonly considered an opportunistic mycosis?

Coccidioidomycosis Signup and view all the answers

What is a key feature of yeast-like fungi?

They exist as single, unconnected cells. Signup and view all the answers

In which of the following conditions do pathogenic dimorphic fungi appear yeast-like?

High temperature and high carbon dioxide Signup and view all the answers

What is the most commonly occurring fungal nosocomial pathogen?

Candida species Signup and view all the answers

Which group of fungi is responsible for cutaneous mycoses, also known as dermatophytoses?

Dermatophytes Signup and view all the answers

What does oral candidiasis commonly present as?

Raised, white plaques Signup and view all the answers

Which of the following correctly describes systemic candidiasis?

A potentially life-threatening infection Signup and view all the answers

What causes tinea versicolor, a superficial skin infection?

Malassezia species Signup and view all the answers

Which factor has contributed significantly to the increase of immunocompromised individuals?

Use of immunosuppressive drugs Signup and view all the answers

What specific type of skin infection does tinea nigra represent?

An infection of the keratinized layers of the skin Signup and view all the answers

Which of the following genera contain species that cause dermatophytoses?

Microsporum Signup and view all the answers

Which population is most likely to develop opportunistic mycoses?

Immunocompromised individuals Signup and view all the answers

Cryptococcosis is caused by which of the following organisms?

Cryptococcus neoformans Signup and view all the answers

What are the characteristic lesions of tinea corporis?

Circular lesions with scaly centers and inflamed periphery Signup and view all the answers

Which statement is true regarding tinea pedis?

It can spread to nails and cause discoloration. Signup and view all the answers

In tinea capitis, what unique feature can be observed under UV light?

Green fluorescence of hair shafts Signup and view all the answers

What is the recommended duration of treatment for tinea unguium?

3 to 4 months Signup and view all the answers

Which of the following statements best describes subcutaneous mycoses?

They are most often acquired through traumatic lacerations or puncture wounds. Signup and view all the answers

What is one characteristic of sporotrichosis?

It produces granulomatous ulcers at the puncture site. Signup and view all the answers

Which organism is responsible for sporotrichosis?

Sporothrix schenckii Signup and view all the answers

Which condition is commonly known as jock itch?

Tinea cruris Signup and view all the answers

Study Notes

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.

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Description

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.