Fungal Infections Flashcards
(26 cards)
What are the clinical forms of Candida albicans infections?
Superficial (e.g., thrush on mucosal surfaces) and invasive (e.g., heart, CNS, eye, liver).
How does Candida albicans appear morphologically at 20°C vs. 37°C?
20°C: Yeast with pseudohyphae.
37°C: Germ tube formation.
What is a common superficial infection caused by Candida albicans?
Thrush (white patches on mucosal surfaces, e.g., mouth, vagina).
What type of patients are most at risk for Cryptococcus neoformans infections?
Immunocompromised patients (e.g., HIV/AIDS, transplant recipients).
What are the primary clinical forms of Cryptococcus neoformans infection?
Pulmonary (lungs, primary site)
CNS (meningitis, encephalitis)
How does Cryptococcus neoformans appear microscopically?
Yeast with a thick gelatinous capsule, staining PAS+ and mucicarmine+.
What are the key histopathological findings in:
a) Immunocompromised patients?
b) Immunocompetent patients?
a) Soap-bubble lesions (capsule-filled spaces)
b) Granulomas/suppuration
What is the primary site of Cryptococcus neoformans infection before dissemination?
The lungs (pulmonary infection).
Which patient population is most at risk for Pneumocystis jirovecii pneumonia (PJP)?
AIDS patients (severely immunocompromised).
What are the classic clinical features of PJP?
Rapidly progressive bilateral pneumonia.
What is the preferred specimen for diagnosing PJP?
Bronchoalveolar lavage (BAL) fluid (shows organisms/exudate).
How does Pneumocystis jirovecii appear on Gomori methenamine silver (GMS) stain?
Cup-shaped or oval yeast with a central dot (GMS+).
What histologic finding is classic for PJP in lung tissue?
Eosinophilic honeycomb exudate in alveolar spaces.
What lab marker supports PJP or invasive fungal infection?
Elevated 1,3-β-D-glucan in serum or BAL.
Match the yeast to its morphologic hallmark:
a) Blastomyces dermatitidis
b) Coccidioides immitis
c) Paracoccidioides brasiliensis
a) Broad-based budding
b) Spherules
c) Mariner’s wheel (multiple budding).
What are the three clinical forms of aspergillosis?
Allergic bronchopulmonary aspergillosis (ABPA)
Colonizing aspergillosis (fungus balls in lung cavities)
Invasive aspergillosis (lungs, heart valves, brain).
How does Aspergillus appear microscopically?
Septate hyphae branching at acute angles (45°).
What are the tissue findings in:
a) Colonizing aspergillosis?
b) Invasive aspergillosis?
a) Fungus ball with sparse/chronic inflammation
b) Angioinvasion → vasculitis, hemorrhagic necrosis.
Which Aspergillus species produces aflatoxin, and what is its complication?
Aspergillus flavus → increased risk of hepatocellular carcinoma.
What is the hallmark of invasive aspergillosis on histopathology?
Angioinvasion leading to vasculitis and necrotizing lesions.
Which patients are at highest risk for colonizing aspergillosis?
Those with pre-existing lung cavities (e.g., from TB, emphysema).
Which patient populations are at highest risk for mucormycosis?
Immunocompromised or diabetic patients.
What are the three clinical forms of mucormycosis?
Pulmonary
Gastrointestinal
Rhinocerebral (nasal eschar → brain/orbit invasion).
How does Mucor appear microscopically?
Non-septate hyphae branching at right angles (90°).
