Mycology Overview and Fungal Diseases

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Questions and Answers

What characteristic distinguishes dimorphic fungi from other fungi?

They can photosynthesize.

They can exist in two different forms depending on temperature. (correct)

They reproduce exclusively through spores.

They lack a cell wall.

Which of the following is an example of a polymorphic fungi?

Coccidioides

Penicillium (correct)

Histoplasma

Sporothrix

What is one notable method for diagnosing fungal diseases?

Blood culture

Ultrasound imaging

Serological testing

Microscopic examination (correct)

Which of the following best describes eukaryotic organisms like fungi?

They contain membrane-bound organelles. Signup and view all the answers

Which condition is associated with subcutaneous mycoses?

Lobomycosis Signup and view all the answers

Which of the following characteristics describes Black Piedra?

Pigmented and hard nodules Signup and view all the answers

Which fungi is associated with causing White Piedra?

Trichophyton tonsurans Signup and view all the answers

What type of infection source is attributed to the geophilic category?

Soil Signup and view all the answers

What distinguishes the nodules of White Piedra from those of Black Piedra?

White Piedra nodules are less pigmented and softer Signup and view all the answers

Which type of diagnostic features are utilized to identify White Piedra microscopically?

Blastoconidia and arthroconidia Signup and view all the answers

Which Trichophyton species causes the severe type of Tinea capitis known as T.favosa?

Trichophyton schoenleinii Signup and view all the answers

What is the primary characteristic of the nodules found in Black Piedra?

Firmly attached and pigmented Signup and view all the answers

What shape do yellow rose gardener's granules typically resemble?

Cigar shape Signup and view all the answers

What type of organism typically causes anthropophilic infections?

Other humans Signup and view all the answers

What is the incubation period for culturing suspected T. mentagrophyte in sterile hair?

2-3 weeks Signup and view all the answers

Which of the following is a characteristic of the mold form of Sporothrix schenckii at room temperature?

Balloon forms Signup and view all the answers

What test provides a positive result through the observation of V shaped perforations in hair shafts?

Hair Perforation Test Signup and view all the answers

What type of fungal forms are expected for Sporothrix schenckii during lab diagnosis?

Both mold and yeast forms Signup and view all the answers

Which of the following best describes the appearance of the yeast form of Sporothrix schenckii?

Cigar shaped yeast Signup and view all the answers

What is the common manifestation of lymphocutaneous sporotrichosis?

Sinus tracts formation Signup and view all the answers

What type of MOT (Mode of Transmission) is associated with Sporothrix schenckii?

Skin puncture Signup and view all the answers

What is the primary causative agent of rhinosporidiosis?

Rhinosporidium seeberi Signup and view all the answers

Which form of the causative agent of rhinosporidiosis is present at room temperature?

Mold Signup and view all the answers

What diagnostic feature is indicative of the rhinosporidiosis pathogen when observed under a microscope?

Sporangium filled with endospores Signup and view all the answers

What symptom is commonly associated with rhinosporidiosis?

Swelling and difficulty in breathing Signup and view all the answers

Which of the following describes the 'Mariner’s wheel appearance' observed in rhinosporidiosis?

Formation of multiple buds Signup and view all the answers

Rhinosporidiosis can cause granulomatous ulcers primarily located in which area?

Nasal and pharyngeal mucosa Signup and view all the answers

Which of the following tests is used in the exoantigen test for rhinosporidiosis?

Band 1, 2, 3 Signup and view all the answers

Coccidioidomycosis is also known as which of the following?

Valley Fever Signup and view all the answers

What characterizes a positive result when incubating C.albicans at 42C?

Presence of Tuberculate Macroconidia Signup and view all the answers

What is a key differentiating feature between C.albicans and C.dubliniensis?

Ability to grow at 42C Signup and view all the answers

Which type of patients are most at risk for opportunistic mycosis?

Immunocompromised patients Signup and view all the answers

What indicates that a cell is a germ tube?

Absence of both constriction and branches Signup and view all the answers

Which of the following is NOT associated with candidiasis?

Pneumonia Signup and view all the answers

What type of fungi typically causes opportunistic mycosis?

Saprophytic fungi Signup and view all the answers

What distinguishing feature do Candida colonies display on BAP?

Foot-like or pedicle appearance Signup and view all the answers

Which of the following conditions is a risk factor for the development of opportunistic mycosis?

Neutropenia Signup and view all the answers

Study Notes

Mycology

Study of fungi (also known as thallophytes).
Eukaryotic, plant-like organisms lacking stems and roots.
Heterotrophs.

Fungi Phases

Polymorphic fungi exist in multiple forms and structures.
Dimorphic fungi have two phases depending on temperature: yeast-like at 37°C (body temperature) and mold-like at 25°C (room temperature). Dimorphic fungi are usually pathogenic. Examples include Sporothrix, Paracoccidioides, Blastomyces, Histoplasma, Talaromyces marneffei (formerly Penicillium marneffei), and Coccidioides.

Subcutaneous Mycoses

Rose Gardener's Disease (Sporotrichosis): Caused by Sporothrix schenckii. Transmitted via skin puncture or inhalation. Presents as lymphocutaneous sporotrichosis. Mold form shows flowerette microconidia, yeast form is cigar-shaped.
Lobomycosis: Information not provided.
Mycetoma: Characterized by sinus tracts and bone involvement. Diagnosed by the presence of pigmented or non-pigmented granules in lesions.

Dermatophytes (Trichophyton)

Trichophyton mentagrophytes: velvety and cottony colonies.
Trichophyton rubrum, Trichophyton schoenleinii, Trichophyton tonsurans, Trichophyton violaceum are also mentioned.
Dermatophytes can be anthropophilic (human source), zoophilic (animal source), or geophilic (environmental source).
Trichophyton tonsurans: rare macroconidia, balloon-shaped microconidia, suede-like colonies lacking red pigment. Hair perforation test positive (V-shaped perforation).
Tinea capitis: fungal infection affecting the scalp. Tinea favosa is a severe form causing permanent alopecia.

Piedra

Black piedra: pigmented, hard, firmly attached nodules; asci with ascospores and chlamydoconidia.
White piedra: less pigmented, slightly soft or mucilaginous, not firmly attached nodules; blastoconidia and arthroconidia.

Systemic Mycoses

Primarily caused by dimorphic fungi.
Acquired through inhalation of spores.
Blastomyces dermatitidis, Coccidioides immitis, and Histoplasma dubliniensis mold forms are germ tube positive.
Infection of the reticuloendothelial system (RES) can affect monocytes, macrophages, and bone marrow tissues.
Room temperature: tuberculate macroconidia.
Body temperature: small budding yeast cells (intracellular).

Opportunistic Mycoses

Fungal infections in immunocompromised or debilitated patients (e.g., cancer, AIDS patients).
Caused by usually non-pathogenic saprophytic fungi.
Neutropenia is a significant risk factor.

Candidiasis

Associated with moniliasis, thrush, mycotic vulvovaginitis, Candida perionychia, and Candida endocarditis.
Candida grows in ordinary culture media, including blood agar plates (BAP), with "foot-like" or pedicle appearance on the colony's side.
Candida albicans grows at 42°C; Candida dubliniensis does not.
Germ tube test: absence of constriction at the base indicates a germ tube; presence of constriction indicates it’s not a germ tube.

Paracoccidioidomycosis

Caused by Paracoccidioides brasiliensis (dimorphic fungus).
Mold form (room temperature): chlamydoconidia and microconidia.
Yeast form (body temperature): multiple buds ("mariner's wheel appearance") and "Mickey Mouse cap" structures.
Exoantigen test: bands 1, 2, 3.
Manifestations include TB-like pulmonary infection, suppurative and granulomatous ulcers of mucosal areas (e.g., nasopharynx).

Coccidioidomycosis (San Joaquin Valley Fever)

Information not provided in detail beyond the name and alternative name.

Laboratory Diagnosis of Fungal Diseases

Microscopic examination: Direct examination of specimens.
Culture: Growing fungi in the laboratory.
Tests: Specific tests such as exoantigen tests (e.g., for Paracoccidioides brasiliensis). Hair perforation tests (for Trichophyton species).

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Description

Explore the fascinating world of mycology with this quiz covering the study of fungi, their phases, and significant fungal diseases. Learn about polymorphic and dimorphic fungi, as well as specific conditions like sporotrichosis and mycetoma. Test your knowledge and deepen your understanding of these essential organisms.