MICRO CHAPTER 22 FINAL

Which microorganisms are found in the domain Eukarya?

Fungi and parasites (protozoa and helminths).

What is the body form of yeast?

A single-celled organism larger than bacteria.

What is a hypha?

A singular long filamentous fungal cell.

What is a mycelium (mold)?

A multicellular organism made of many hyphae.

How do yeast reproduce?

By budding.

How does mycelium reproduce?

Sexually or asexually through spores.

What is a mycosis?

A fungal disease or infection.

What is thermal dimorphism?

Ability of fungi to switch between mold (30°C) and yeast (37°C).

What body form does fungi have below 30°C?

Mold.

What body form does fungi have at 37°C (human body)?

Yeast.

Do true or opportunistic fungal pathogens exhibit thermal dimorphism?

True fungal pathogens.

How are true and opportunistic fungal pathogens different?

True pathogens have virulence factors and dimorphism; opportunists do not.

Where are true fungal pathogens found?

In soil, endemic to specific regions.

Where are opportunistic fungal pathogens found?

Normal flora or worldwide in soil.

How are most true fungal pathogens transmitted?

Inhaling dust or soil with spores.

What type of infection do true fungal pathogens cause?

Respiratory infections, sometimes systemic or skin lesions.

What body layers are infected by intermediate virulence fungi?

Subcutaneous, cutaneous, or superficial layers.

What disease does Sporothrix schenckii cause?

Rose gardener’s disease.

How is Sporothrix schenckii transmitted?

Through thorn pricks, cat bites, or scratches.

Which skin layer does Sporothrix schenckii infect?

Subcutaneous layer.

What are dermatophytes?

Fungi that infect skin, hair, and nails (keratinized tissues).

Why do dermatophytes infect keratinized layers?

They feed on keratin.

What kind of environment do dermatophytes prefer?

Moist environments.

What is ringworm?

Fungal infection caused by dermatophytes.

What infections do dermatophytes cause?

Tinea infections.

What part of the body does tinea capitis affect?

Scalp, eyebrows, eyelashes.

What part of the body does tinea cruris affect?

Groin area.

What part of the body does tinea pedis affect?

Feet.

What part of the body does tinea corporis affect?

Body.

What part of the body does tinea barbae affect?

Beard/groin area.

What part of the body does tinea unguium affect?

Finger or toenails.

What part of the body does tinea manuum affect?

Hand.

How are tinea infections treated?

Topical antifungals, debridement, or UV light.

What skin layer does tinea versicolor infect?

Superficial outer epidermis.

What are the symptoms of tinea versicolor?

Scaling or mottling of the skin.

Where does Piedra infection occur?

On hair shafts.

What are the symptoms of Piedra?

White or black nodules on hair.

Name the four opportunistic fungal pathogens.

Candida albicans, Cryptococcus neoformans, Pneumocystis jiroveci, Aspergillus fumigatus.

Which opportunistic fungus causes the most nosocomial infections?

Candida albicans.

What are the three localized infections caused by Candida albicans?

Oral thrush, vulvovaginal candidiasis, cutaneous candidiasis.

What does oral thrush look like?

White, patchy infection in mouth/throat.

What are symptoms of vulvovaginal candidiasis?

Itching and yellow-white discharge.

What is cutaneous candidiasis?

White, patchy skin or mucous membrane infections.

Where does Cryptococcus neoformans infection start?

In the lungs.

What can Cryptococcus neoformans infection progress to?

Meningitis and death in immunocompromised patients.

Who is most affected by Pneumocystis jiroveci?

AIDS patients.

What disease does Pneumocystis jiroveci cause?

Pneumocystis pneumonia (PCP).

What is the result of untreated PCP in AIDS patients?

Lung secretions block breathing → can be fatal.

What sites does Aspergillus fumigatus infect?

Lungs, skin, and sinuses.

What does Aspergillus fumigatus form in the lungs?

Fungal balls.

What happens if Aspergillus fumigatus disseminates?

Necrotic pneumonia and fatal systemic spread.