T20 - Systemic Mycoses (Mold)

Which fungal pathogen produces spherules instead of yeast cells in host tissues?

Coccidioides species

What morphological form do most dimorphic fungi assume at 25°C in the environment?

Mold (hyphae)

What morphological form do most dimorphic fungi assume at 37°C in the host?

Yeast

What are the two main causative agents of Coccidioidomycosis?

• Coccidioides immitis
• Coccidioides posadasii

What is the infectious morphological form of Coccidioides found in dry, wind-blown dust?

Arthroconidia (arthrospores)

What large structure does Coccidioides form in human lung tissue after inhalation?

Spherule

What reproductive structures are contained within mature Coccidioides spherules?

Endospores

What is the common name for the self-limited influenza-like illness caused by Coccidioides?

Valley fever

What percentage of primary Coccidioides infections are completely asymptomatic?

60%

Which gender is generally more susceptible to Coccidioidomycosis?

Males

Which specific subpopulation of women is at greater risk for severe Coccidioidomycosis?

Pregnant women

What two common stains are used to microscopically visualize Coccidioides spherules in exudates?

• Potassium hydroxide (KOH)
• Calcofluor white

What type of colonies does Coccidioides typically form on Sabouraud's agar?

Fluffy colonies

Which dimorphic fungal pathogen is characterized in culture by alternating arthroconidia and empty nucleate segments?

Coccidioides species

Does Coccidioidomycosis spread from person to person?

No

What specific immune status poses the highest risk for disseminated Coccidioidomycosis?

Weakened immune systems

Which two ethnic groups are noted to be at particularly high risk for severe Coccidioides infection?

• African-Americans
• Filipinos

What serologic test is frequently used to detect IgM antibodies for Coccidioides?

Latex agglutination test

What two serologic tests are primarily used to detect IgG antibodies for Coccidioides?

• Immunodiffusion (ID)
• Complement fixation (CF)

What environmental conditions facilitate the most effective aerial dispersal of Coccidioides?

Hot, dry conditions

What is the primary causative agent of Paracoccidioidomycosis?

Paracoccidioides brasiliensis

What is the classic microscopic appearance of Paracoccidioides brasiliensis at 37°C?

Ship's wheel appearances

What type of lung lesions are characteristic of early Paracoccidioides infection?

Pulmonary granulomas

What specific types of severe mucosal lesions characterize disseminated Paracoccidioidomycosis?

Ulcerative lesions of the mouth, nose, and larynx

Which gender is significantly more susceptible to Paracoccidioides brasiliensis infection?

Males

What hormone directly inhibits the progression of Paracoccidioides brasiliensis infection in females?

Estrogen

Does Paracoccidioidomycosis spread from person to person?

No

What diagnostic test titers tend to correlate directly with the severity of Paracoccidioidomycosis?

Complement fixation (CF) titers

What is the morphological form of Paracoccidioides brasiliensis at environmental temperatures below 37°C?

Mycelia

What severe facial disfigurement sequela can result from chronic mucosal Paracoccidioidomycosis?

Microstomia

What is a common alternative name for Paracoccidioidomycosis based on its geography?

South American blastomycosis

What cells remain attached to the mother cell in Paracoccidioides to create its classic microscopic appearance?

Multiple buds

What is the causative agent of Blastomycosis?

Blastomyces dermatitidis

What is the classic microscopic appearance of Blastomyces dermatitidis at 37°C?

Broad-based budding yeast

What distinct structural feature of Blastomyces yeast cells is prominent under tissue microscopy?

Thick cell wall

What type of lesions does chronic Blastomycosis typically cause in the lungs?

Granulomatous and suppurative lesions

What is the estimated fatality rate of untreated disseminated Blastomycosis?

78%

To which two organ systems does Blastomycosis preferentially disseminate from the lungs?

• Skin
• Bones

What specific genitourinary organs are classically involved in extrapulmonary Blastomycosis in men?

Prostate and epididymis

What morphology does Blastomyces dermatitidis exhibit at 25°C in culture?

"Lollipop-like" conidia

Which gender is more frequently affected by Blastomycosis?

Males

What type of domestic animal is commonly infected with Blastomycosis in endemic areas?

Dogs

What environmental source harbors the infectious mycelia of Blastomyces dermatitidis?

Soil containing microfoci

What type of skin lesions typically develop in cutaneous Blastomycosis?

Verrucous or ulcerative lesions

Can Blastomycosis severely affect healthy, immunocompetent individuals?

Yes

Is Blastomycosis a communicable disease between humans?

No

What is the causative agent of Histoplasmosis?

Histoplasma capsulatum

What environmental sources are heavily associated with Histoplasma capsulatum?

Soil contaminated with bird or bat droppings

What is the classic microscopic appearance of Histoplasma capsulatum in human tissue?

Small intracellular budding yeast

Which host immune cells does Histoplasma capsulatum characteristically parasitize?

Alveolar macrophages

What distinctive morphological structures does Histoplasma capsulatum produce at temperatures below 37°C?

Tuberculate macroconidia and microconidia

How is Histoplasma capsulatum transmitted to humans?

Inhalation of conidia

In which specific patient population does severe disseminated histoplasmosis most frequently occur?

Immunosuppressed persons

What organs are characteristically enlarged in disseminated histoplasmosis?

Liver and spleen (hepatosplenomegaly)

What chronic bacterial lung disease does Chronic Pulmonary Histoplasmosis closely mimic?

Tuberculosis

What skin condition can manifest in disseminated Histoplasmosis, resembling a common viral infection?

Molluscum contagiosum-like umbilicated lesions

What is the most prevalent endemic fungal infection in the United States?

Histoplasmosis

What laboratory stain is highly effective for identifying intracellular Histoplasma yeast in bone marrow smears?

Giemsa staining

What types of agar are typically used to culture Histoplasma capsulatum?

• Glucose-cysteine blood agar
• Sabouraud's agar

What specific diagnostic test utilizes the "h antigen" for Histoplasmosis?

Immunodiffusion (ID) test

What distinctive structural feature surrounds Histoplasma yeast cells in the body?

Capsule

What specific class of fungi does Histoplasma capsulatum belong to?

Eurotiomycetes

Does Histoplasmosis spread directly from person to person?

No

What clinical finding can occur if calcified Histoplasma granulomas erode into the airways?

Broncholithiasis

What systemic toxicity is a frequent complication of disseminated Histoplasmosis?

Bone marrow toxicity

What is the causative agent of Penicilliosis (Talaromycosis)?

Penicillium (Talaromyces) marneffei

What animal serves as the primary natural reservoir for Talaromyces marneffei?

Bamboo rats

What is the distinct microscopic appearance of Talaromyces marneffei in human tissue?

Intracellular fission yeast

How do the yeast-like cells of Talaromyces marneffei divide in host tissues?

Fission

What distinct pigment is produced by Talaromyces marneffei mold colonies grown at 25°C?

Red diffusible pigment

What specific skin lesions are commonly seen in severe, disseminated Talaromycosis?

Molluscum contagiosum-like lesions

In what patient population is Talaromycosis primarily a severe, life-threatening opportunistic infection?

HIV/AIDS patients

What weather condition is associated with a seasonal increase in Talaromycosis infections?

Tropical rainy seasons

What specific host immune cells are heavily targeted by Talaromyces marneffei?

Dendritic cells and macrophages

What structures are characteristic of the mold phase of Talaromyces marneffei under the microscope?

Phialides producing conidia

What is the most common causative agent of Aspergillosis?

Aspergillus fumigatus

What is the classic microscopic appearance of Aspergillus hyphae in tissue?

Dichotomously branched, septate hyphae

At what angle do Aspergillus hyphae typically branch?

45 degrees

What is the primary ecological niche of Aspergillus species?

Soil or decaying vegetation

What disease is caused by a hypersensitivity reaction to Aspergillus antigens, typically in asthmatic patients?

Allergic bronchopulmonary aspergillosis (ABPA)

What is the term for a localized, non-invasive Aspergillus infection growing in a preformed pulmonary cavity?

Aspergilloma

What severe condition develops when Aspergillus hyphae actively invade blood vessels in immunocompromised hosts?

Invasive Aspergillosis

What severe vascular consequence directly results from Aspergillus tissue and blood vessel invasion?

Thrombosis and local tissue necrosis

Which specific immune cells are primarily responsible for controlling Aspergillus hyphae in the lung?

Neutrophils

What enzyme produced by Aspergillus breaks down hydrogen peroxide, posing a risk to CGD patients?

Catalase

What specific antigen is commonly detected in serology tests for invasive Aspergillosis?

Galactomannan antigen

What fungal element is easily aerosolized and serves as the primary infectious unit of Aspergillus?

Conidia

Is Aspergillosis a contagious infection between humans?

No

What are the two most common genera that cause Mucormycosis (zygomycosis)?

• Rhizopus
• Mucor

What is the classic microscopic appearance of Mucormycosis hyphae in tissue?

Broad, ribbon-like, aseptate hyphae

What structure contains the asexual spores of Mucorales fungi?

Sporangium

What specific root-like structures help differentiate Rhizopus species from Mucor species?

Rhizoids

What is the most common clinical form of Mucormycosis?

Rhinocerebral mucormycosis

What metabolic condition strongly predisposes patients to rhinocerebral mucormycosis?

Diabetic ketoacidosis

What is a key pathophysiological feature of Mucormycosis tissue invasion?

Angioinvasive growth with hemorrhage, thrombosis, and necrosis

What host cell defect (due to disease or drugs) is a major risk factor for pulmonary mucormycosis?

Neutropenia

How do Mucormycosis sporangiospores typically enter the human body to cause rhinocerebral or pulmonary disease?

Inhalation

What available free mineral in the host strongly supports Mucormycosis hyphal proliferation?

Free iron

Does Mucormycosis spread from person to person?

No

What aggressive, high-mortality complication can cutaneous Mucormycosis lead to?

Necrotizing fasciitis