Fungi Structure and Growth

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Questions and Answers

What is the primary mode of transmission of Coccidioides immitis?

Through vector-borne transmission

Through ingestion of contaminated food

Through inhalation of arthroconidia (correct)

Through skin contact

Which of the following groups is most commonly affected by Blastomycosis?

Men between the ages of 40 and 60 years

Men between the ages of 20 and 40 years (correct)

Children under the age of 10 years

Women between the ages of 20 and 40 years

What is the common name for coccidioidomycosis?

Desert Fever

Valley Fever (correct)

California Fever

San Joaquin Fever

Which of the following is NOT a characteristic of Cryptococcus neoformans?

Gram-negative Signup and view all the answers

What is the main difference between the yeast and hyphal forms of Candida albicans?

The yeast form produces germ tubes Signup and view all the answers

What is the primary site of infection for Pneumocystis jiroveci?

Lungs Signup and view all the answers

Which of the following fungi is NOT an opportunistic mycotic pathogen?

Saccharomyces cerevisiae Signup and view all the answers

What is the term for the warty patches surrounded by tiny painless abscesses seen in blastomycosis?

Skin lesions Signup and view all the answers

What is the term for the fungal outer wall that prevents phagocytosis?

Antiphagocytic properties Signup and view all the answers

Which of the following is a characteristic of Aspergillus fumigatus?

Septate hyphae that branch at a V-shaped angle Signup and view all the answers

What is the method of reproduction in yeast cells?

Budding Signup and view all the answers

What is the characteristic feature of mold cells?

Long filaments of cells called hyphae Signup and view all the answers

At what temperature do fungi typically exist as yeast?

Body temperature (37°C) Signup and view all the answers

What is the primary factor that governs the incidence and spread of fungal infections?

Ubiquity of infectious organisms Signup and view all the answers

What is the primary mode of transmission of Histoplasma capsulatum?

Inhalation of conidia Signup and view all the answers

What is the typical habitat of Histoplasma capsulatum?

Soil contaminated with bat or bird droppings Signup and view all the answers

What is the percentage of residents in areas where Histoplasma capsulatum is common who test positive for exposure?

50% - 90% Signup and view all the answers

What is the treatment of choice for Histoplasmosis if necessary?

Amphotericin B Signup and view all the answers

What is the result of microconidia converting to yeast form after inhalation?

Phagocytosis by immune cells Signup and view all the answers

What group of individuals is at increased risk of Histoplasmosis infection?

People who live and work in the vicinity of bat or bird droppings Signup and view all the answers

Study Notes

Fungal Infections

Coccidioidomycosis is caused by Coccidioides immitis and can be symptomatic or asymptomatic, also known as Valley Fever.
It is restricted to certain geographical areas and occurs through inhalation of arthroconidia.
The fungal outer wall has antiphagocytic properties, preventing elimination.
Disseminated coccidioidomycosis can occur in patients with AIDS and those on immunosuppressive therapy.

Blastomycosis

Blastomycosis is caused by Blastomyces dermatitidis and primarily affects the lungs.
Spores of the fungi enter through the respiratory system and can spread through the bloodstream to affect other parts.
Men between 20 and 40 years old are most commonly infected.
Blastomycosis is not increased in AIDS patients.

Pneumocystis Pneumonia (PCP)

PCP is a lethal pneumonia common in AIDS patients, caused by Pneumocystis (carinii) jiroveci.
It is never been grown in culture, and most information comes from clinical observations.

Candida albicans

Candida albicans is a yeast that forms pseudohyphae and hyphae when it invades tissue.
It can cause thrush, disseminated candidiasis, and chronic mucocutaneous candidiasis.
Transmission is rare, but can cause pneumonia, resulting in fever, coughing, difficulty breathing, and tachypnea.
Laboratory diagnosis involves microscopic examination of tissue, revealing yeasts and pseudohyphae.

Cryptococcus neoformans

Cryptococcus neoformans is a heavily encapsulated yeast that causes cryptococcosis, especially cryptococcal meningitis.
It is found in soil, enriched by pigeon droppings, and transmission occurs through inhalation of airborne yeast cells.

Aspergillus fumigatus

Aspergillus fumigatus is a mold that causes invasive aspergillosis, allergic bronchopulmonary aspergillosis, and aspergilloma (fungus ball).
It is found in soil and transmission occurs through inhalation of airborne spores (conidia).

Basic Mycology

Fungi are eukaryotic organisms that exist in two basic forms: yeasts and molds.
Yeasts are single cells that reproduce by budding, while molds consist of long filaments of cells called hyphae and reproduce by cell division.
Some fungi are dimorphic, existing as yeasts or molds depending on temperature.

Factors of Fungal Infection

Two major factors govern the incidence and spread of fungal infection: ubiquity of infectious organisms and adaptive immune response.
Immunocompromised patients are at much greater risk of fungal infection.

Histoplasmosis

Histoplasmosis is caused by Histoplasma capsulatum and occurs in soil contaminated with bat or bird droppings.
It is commonly found in temperate, subtropical, and tropical zones, and 50% - 90% of residents in these areas test positive for exposure.
People who live and work in the vicinity of bat or bird droppings are at increased risk of infection.
Amphotericin B is the treatment of choice if necessary.

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Description

Learn about the basic structure and growth of fungi, including yeasts and molds, and how they reproduce. Discover how some fungi can exist in both forms depending on temperature.