Podcast
Questions and Answers
Which of the following fungi require a temperature of 37°C for growth?
Which of the following fungi require a temperature of 37°C for growth?
What is the main stain used in stained preparations for direct microscopic examination of fungi?
What is the main stain used in stained preparations for direct microscopic examination of fungi?
Which laboratory diagnostic test is used primarily for the detection of specific antibodies for systemic mycosis?
Which laboratory diagnostic test is used primarily for the detection of specific antibodies for systemic mycosis?
The presence of which substance in blood is indicative of invasive fungal infections?
The presence of which substance in blood is indicative of invasive fungal infections?
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What type of media is Sabouraud's dextrose agar (SDA) classified as?
What type of media is Sabouraud's dextrose agar (SDA) classified as?
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Which antifungal drug acts by inhibiting cell wall synthesis?
Which antifungal drug acts by inhibiting cell wall synthesis?
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Which of the following fungi is typically cultured on Sabouraud's dextrose agar?
Which of the following fungi is typically cultured on Sabouraud's dextrose agar?
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Which laboratory specimen is not typically used for fungal infection diagnosis?
Which laboratory specimen is not typically used for fungal infection diagnosis?
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Which statement about fungi is incorrect?
Which statement about fungi is incorrect?
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Which antifungal category includes drugs that inhibit ergosterol synthesis?
Which antifungal category includes drugs that inhibit ergosterol synthesis?
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Study Notes
Introduction to Medical Mycology
- Lecture covers general properties and structure of fungi, morphology of fungi, classification of medically important fungi, and human mycoses.
- The lecture also includes laboratory diagnosis of fungal infections, including specimens (skin scrapings, hairs, nails, respiratory secretions, and blood), and laboratory diagnostic tests including direct microscopic examination, fungal culture, serological tests, skin tests, and molecular methods like PCR.
Laboratory Diagnosis of Fungal Infections
- Specimens: Collected based on infection site (skin scrapings, hairs, nails, respiratory secretions, blood).
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Laboratory Diagnostic Tests:
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Direct microscopic examination:
- Unstained preparations (wet mount): Using KOH (10-30%) for skin scrapings, nails, or hairs
- Stained preparations: Using Lactophenol cotton blue (main stain), Silver stain, and Periodic acid Schiff (PAS).
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Fungal culture:
- All fungi are aerobic.
- Temperature requirements: Most fungi: 25-27°C. Yeast: 37°C. Dimorphic fungi: 25°C & 37°C.
- Incubation time: Typically 7-10 days, but some (like Candida & Aspergillus) take 24 to 72 hours.
- Sabouraud's dextrose agar (SDA): A specific enriched and selective media for fungi, useful for growing fungi. Different types of fungal growth on SDA can be viewed (e.g., Aspergillus niger, Aspergillus flavus, Mucor, Penicillium spp. and Candida albicans).
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Serological tests:
- Detecting antigens and antibodies (e.g., beta-D-glucan, galactomannan).
- β-D-Glucan detection in blood samples is diagnostic for invasive fungal infections.
- Galactomannan detection in blood samples is diagnostic for invasive aspergillosis.
- Detection of specific antibodies is used to diagnose systemic mycosis.
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Direct microscopic examination:
Antifungal Therapy
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Mechanism of Action:
- Inhibit cell wall synthesis: Caspofungin
- Inhibit ergosterol synthesis: Polyenes (nystatin & amphotericin B), Azoles (miconazole & fluconazole)
- DNA synthesis inhibitors: Flucytosine.
Important Topics
- Components of the fungal cell membrane: Ergosterol
- Tinea pedis: Fungal infection of the toe web
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Description
This quiz covers the fundamental concepts of medical mycology, including the general properties and structure of fungi, their classification, and the various types of human mycoses. Additionally, it emphasizes laboratory diagnosis methods for fungal infections, detailing specimen collection and various diagnostic tests like microscopic examination and fungal culture.
