Subcutaneous Mycoses and Chromoblastomycosis Quiz
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Questions and Answers

What are the primary clinical manifestations of progressive pulmonary disease caused by systemic mycoses?

Cough, weight loss, chest pain, and fever.

What are the two species of Blastomyces responsible for blastomycosis?

Blastomyces dermatitidis and Blastomyces gilchristii.

How can systemic mycoses lead to skin and bone complications?

It results in ulcerative lesions of the skin and bone.

What is the geographic distribution of blastomycosis?

<p>It primarily occurs in North America and parts of Africa.</p> Signup and view all the answers

What makes Coccidioides one of the most virulent mycotic agents?

<p>It is considered the probable most virulent of all human mycotic agents.</p> Signup and view all the answers

What are the budding yeast cells characteristics seen in cutaneous and mucosal lesions for patients with immunocompromised conditions?

<p>They are 15 to 30 μm in diameter and exhibit multipolar budding resembling a 'mariner’s wheel.'</p> Signup and view all the answers

What are some clinical manifestations of chronic pulmonary histoplasmosis in patients with COPD?

<p>It can lead to reticuloendothelial cytomycosis and may cause signs similar to tuberculosis due to granuloma formation.</p> Signup and view all the answers

How is Histoplasma capsulatum identified in laboratory diagnosis?

<p>It is identified by direct microscopic morphology when yeast cells are stained with Giemsa or Wright stain.</p> Signup and view all the answers

Describe the distribution and endemicity of Histoplasma capsulatum.

<p>Histoplasma capsulatum has a worldwide distribution with the highest endemicity in the Ohio, Missouri, and Mississippi river deltas.</p> Signup and view all the answers

What morphological changes occur to the mycelium of Histoplasma capsulatum as it matures?

<p>The mycelium initially appears white but turns gray or gray-brown as the colony matures.</p> Signup and view all the answers

What does the clustered appearance of yeast cells in tissue suggest in histoplasmosis?

<p>It suggests the presence of yeast cells within macrophages, appearing pseudo-encapsulated.</p> Signup and view all the answers

List some alternative names for histoplasmosis.

<p>It is also known as cave disease, spelunker’s disease, and Darling disease.</p> Signup and view all the answers

What are the possible severe outcomes of disseminated histoplasmosis in immunocompromised patients?

<p>It can lead to progressive and potentially fatal disseminated disease.</p> Signup and view all the answers

What is a primary characteristic of the hyphae observed in Mucorales?

<p>They are broad, irregular in width, ribbon-like, and aseptate.</p> Signup and view all the answers

Describe the typical morphology of Syncephalastrum colonies.

<p>They exhibit a woolly appearance and change color from white to gray or brown with age.</p> Signup and view all the answers

How do rhizoids in Mucorales differ from those in Rhizopus spp.?

<p>Mucorales have internodal rhizoids that originate from hyphae between the conidiophores and are more delicate.</p> Signup and view all the answers

What is the unique feature of sporangiophores in some Mucorales?

<p>They can collapse umbrella-like after maturing.</p> Signup and view all the answers

What color variations are commonly observed in pathogenic species of Mucorales?

<p>They form colonies that are green to tan in color.</p> Signup and view all the answers

What type of arrangement do merosporangia have in Syncephalastrum?

<p>Merosporangia are cylindric and arranged in 'daisy petals' around a small spherical columella.</p> Signup and view all the answers

Identify a key ecological niche where Mucorales are commonly found.

<p>They are found in soil, dung, and decomposing organic matter.</p> Signup and view all the answers

What notable feature allows some species of Mucorales to produce pigments?

<p>Some species possess diffusible subsurface pigments that can be seen on various media.</p> Signup and view all the answers

What is the primary mode of transmission for coccidioidomycosis?

<p>Inhalation of only a few arthroconidia.</p> Signup and view all the answers

What are the preferred specimens for laboratory diagnosis of primary coccidioidomycosis?

<p>Tissue or purulent material from cutaneous skin lesions.</p> Signup and view all the answers

What are some types of clinical infections associated with coccidioidomycosis?

<p>Asymptomatic pulmonary disease and allergic manifestations.</p> Signup and view all the answers

What microscopy techniques can enhance the detection of yeast cells in coccidioidomycosis?

<p>KOH (10%) or calcofluor white may be used.</p> Signup and view all the answers

Describe the morphology of the mold phase for coccidioidomycosis.

<p>Conidia are borne on short lateral branches and are ovoid to dumbbell-shaped, varying from 2 to 10 μm in diameter.</p> Signup and view all the answers

What clinical conditions may arise as allergic manifestations from coccidioidomycosis?

<p>Toxic erythema, erythema nodosum, and arthritis.</p> Signup and view all the answers

What characteristic finding in microscopy can suggest a diagnosis of coccidioidomycosis?

<p>Large, spherical, refractile yeasts with double-contoured walls.</p> Signup and view all the answers

What evidence of strong immunity to reinfection can be detected in individuals with coccidioidomycosis?

<p>The coccidioidin skin test.</p> Signup and view all the answers

What is a characteristic appearance of Cladosporium conidia?

<p>Cladosporium conidia display a shield-like appearance.</p> Signup and view all the answers

How are Curvularia conidia typically structured?

<p>Curvularia conidia are often crescent-shaped and can have three to five cells of unequal size.</p> Signup and view all the answers

In what type of patients is Curvularia commonly associated with chronic sinusitis?

<p>Curvularia is often associated with chronic sinusitis in immunocompromised patients.</p> Signup and view all the answers

What is the reproductive characteristic that differentiates true yeasts from yeastlike fungi?

<p>True yeasts reproduce sexually by forming ascospores or basidiospores.</p> Signup and view all the answers

What type of conidiophores do Curvularia produce?

<p>Curvularia produces multicelled conidia on sympodial conidiophores.</p> Signup and view all the answers

What color variations can be observed in the hyphae of Cladosporium?

<p>Cladosporium hyphae can appear in colors ranging from brown to olive to black.</p> Signup and view all the answers

What does an increased incidence of yeast infections indicate in clinical settings?

<p>An increased incidence provides evidence for identifying yeasts at the species level.</p> Signup and view all the answers

What distinguishes yeastlike fungi from true yeasts?

<p>Yeastlike fungi are isolates not capable of sexual reproduction.</p> Signup and view all the answers

What diagnostic methods are primarily used to identify Cryptococcus neoformans?

<p>The India ink test and cryptococcal antigen tests are primarily used.</p> Signup and view all the answers

What characteristic appearance does Cryptococcus neoformans have when viewed under UV light?

<p>It has a blue-white color when stained and viewed under ultraviolet light.</p> Signup and view all the answers

What is the significance of blastoconidia in the characterization of Cryptococcus?

<p>Blastoconidia are the only form seen in Cryptococcus, indicating its yeast nature.</p> Signup and view all the answers

What type of infections is Cryptococcus neoformans primarily associated with?

<p>It is primarily associated with opportunistic infections like meningitis and pneumonia.</p> Signup and view all the answers

What is the appearance of Pneumocystis jirovecii cysts when stained with silver stain?

<p>Pneumocystis jirovecii cysts appear distinct and are visible under silver staining.</p> Signup and view all the answers

What does the term 'mucoid appearance' refer to in the context of Cryptococcus?

<p>It refers to the organism's appearance due to its protective capsule.</p> Signup and view all the answers

How can Cryptococcus be visualized in cerebrospinal fluid?

<p>Cryptococcus can be visualized using an India ink preparation from cerebrospinal fluid.</p> Signup and view all the answers

Which staining methods are mentioned for diagnosing Trichosporon species?

<p>Giemsa stain and Grocott's methenamine silver (GMS) stain are mentioned.</p> Signup and view all the answers

Flashcards

Systemic Mycoses Agents

Various fungi causing systemic infections, potentially leading to severe lung or other organ damage.

Blastomycosis Cause

Caused by two species of Blastomyces, primarily Blastomyces dermatitidis, in North America and parts of Africa.

Blastomycosis Symptoms

Symptoms can include progressive pulmonary disease, skin/bone ulcers, and organ involvement in immunocompromised patients.

Mycotic Agent Virulence

Some fungal agents are considered highly virulent, capable of causing swift and severe system-wide infections.

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Coccidioides Species

Similar but different species of Coccidioides (e.g., C. immitis) are also impactful pathogens.

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Coccidioidomycosis transmission

Inhalation of arthroconidia causes primary coccidioidomycosis.

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Coccidioidomycosis Lab Diagnosis

Microscopic examination of tissue/purulent material from skin lesions reveals large, spherical, refractile yeasts with a double-walled structure.

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Coccidioidomycosis Yeast Size

Yeasts are 8 to 15 μm in diameter.

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Coccidioidomycosis Mold Phase

Conidia are dumbbell-shaped or ovoid, and on short lateral branches.

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Asymptomatic Coccidioidomycosis

Can involve pulmonary disease or allergic manifestations without symptoms.

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Coccidioidomycosis Allergic Manifestations

Toxic erythema, erythema nodosum, erythema multiforme, arthritis are possible signs.

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Coccidioidin Skin Test

A test used to detect strong immunity to future coccidioidomycosis infection.

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Coccidioidomycosis Specimen Type

Specimens like tissue or pus from skin lesions are used.

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Histoplasmosis

A systemic mycosis caused by Histoplasma capsulatum, often characterized by pulmonary involvement.

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Histoplasma capsulatum

The fungus that causes histoplasmosis; exists in both mycelial and yeast forms.

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Yeast form (Histoplasma)

Round, budding yeast cells (15-30 μm) in tissue, often found in macrophages.

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Mycelial form (Histoplasma)

The filamentous growth stage of Histoplasma capsulatum, initially white, turning gray-brown in cultures.

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Microscopic morphology (Histoplasma)

Small yeast cells with a single bud, connected by delicate filaments when stained with Giemsa or Wright.

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Chronic pulmonary histoplasmosis

Histoplasmosis affecting the lungs over a prolonged time.

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Immunocompromised patients (histoplasmosis)

Patients with weakened immune systems are more susceptible to severe and disseminated histoplasmosis.

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Laboratory Diagnosis (Histoplasmosis)

Direct microscopic examination, staining with Giemsa or Wright stain, to visualize yeast cells.

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Lichtheimia infection origin

Infection typically begins in the sinuses.

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Lichtheimia characteristics

Broad, irregular ribbon-like, aseptate hyphae, sporangia with a woolly appearance.

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Lichtheimia colony color

White, gray, or brown.

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Lichtheimia habitat

Soil and decaying vegetation.

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Merosporangia shape

Arrangement of cylindric sporangia like "daisy petals" around a small round center.

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Uniseriate Sporangia

Phialides attached directly to a vesicle at end of the conidiophore.

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Rhizoid comparison

Similar to Rhizopus but more delicate.

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Lichtheimia pathogen rarity

Rare cause of human disease.

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Cladosporium Infection

Infection caused by Cladosporium fungus, often entering through sinuses or wounds. Characterized by brown to black hyphae and branched, shield-shaped conidia.

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Curvularia Infection

A fungal infection often found in individuals with weakened immune systems, primarily manifesting as chronic sinusitis. Characterized by crescent-shaped conidia with multiple cells.

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Yeast Reproduction

Yeasts can reproduce sexually by forming ascospores or basidiospores. Those that don't reproduce sexually are called yeastlike fungi.

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Yeast Infections: Incidence

Yeast infections are becoming increasingly common.

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Yeast Classification

Yeasts are classified based on their reproduction method: True yeasts reproduce sexually, while yeastlike fungi do not.

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Yeast Importance

Yeast identification is important because it helps determine yeast species.

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Yeast Terminology

All organisms capable of reproducing as yeasts are referred to as 'yeasts,' even if they don't reproduce sexually.

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Yeast Research

The increasing prevalence of yeast infections drives the need for further research and understanding.

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Cryptococcus neoformans

A type of fungus that causes opportunistic infections, notably meningitis, pneumonia, and septicemia. It is known for its characteristic mucoid appearance due to a capsule surrounding the organism.

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India Ink Stain

A staining technique used to identify encapsulated yeast organisms, like Cryptococcus neoformans, in cerebrospinal fluid. The ink creates a black background, highlighting the clear halo of the capsule around the yeast cells.

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Cryptococcal Antigen Tests

These tests are replacing India ink preparations for detecting Cryptococcus neoformans in patients. They are more sensitive and accurate in identifying the presence of cryptococcal antigens in bodily fluids.

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Giemsa Stain

A type of stain used for identifying various microbial organisms, including Pneumocystis jirovecii. It helps visualize the morphology and structure of the organisms.

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Grocott's Methenamine Silver Stain (GMS)

A staining technique used for detecting Pneumocystis jirovecii in tissue samples. It stains the organism's cell wall, helping to visualize its presence.

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Calcofluor White Stain

A fluorescent stain used to identify fungal organisms, including Cryptococcus neoformans, that exhibit a blue-white color when viewed under UV light. It allows for rapid and sensitive detection.

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Blastoconidia

The budding form of a fungal organism, often observed in Cryptococcus neoformans. These are round, single-celled structures that can multiply by budding to give rise to new fungal cells.

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Pneumocystis jirovecii

A type of fungus that causes pneumonia, especially in individuals with weakened immune systems. It is a common opportunistic infection in people with HIV/AIDS.

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Study Notes

Subcutaneous Mycoses

  • Affect subcutaneous tissue
  • Usually result from foreign objects implanting into the skin, allowing fungi from soil or decaying matter to enter the host.
  • Causative organisms are commonly found in soil or decaying vegetation.
  • Infections are categorized based on the disease process they cause.
  • Chromoblastomycosis, a fatal fungal infection, is prevalent in Arizona and California.
  • Other types of chromoblastomycosis include verrucous dermatitidis and nodules that become ulcerated or crusted.
  • Chronic infection typically develops months to years after traumatic inoculation.

Chromoblastomycosis Manifestations

  • Lesions can manifest in various ways, including:
    • Lower leg lesion (lasting 3 months)
    • Confluent nodular lesions (on the knee)
    • Cauliflower-like or tumor-like lesions
    • Lesions with serpiginous and verrucous contours (showing scarring)

Chromoblastomycosis Diagnosis

  • KOH (10-40%) analysis
  • Histopathology (finding muriform cells, which are sclerotic bodies. These are usually 5-12 micrometers in diameter.)
  • Direct mycological examination
  • Immunodiagnosis

Agents of Chromoblastomycosis

  • Cladophialophora: Septate hyphae found inside tissue, and hyphae can be found in joints.
  • Phialophora: Sclerotic bodies and hyphae are present in the subcutaneous tissue.
  • Fonsecaea: Sclerotic bodies are observed in subcutaneous and lung tissue

Additional Information

  • ELISA is used to identify the presence of specific antigens from chromoblastomycosis
  • Microscopic morphology of various fungi causing chromoblastomycosis is detailed in table 27-2, showing characteristics like conidiogenous cells, conidia, and conidiophores.

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Mycology and Virology Midterms PDF

Description

Test your knowledge on subcutaneous mycoses, particularly chromoblastomycosis, and its manifestations. This quiz covers the causative organisms, clinical presentations, and diagnostic techniques associated with this fungal infection. Learn how environmental factors contribute to the disease process and explore the various lesions that can develop over time.

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