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Questions and Answers
Which structure is primarily responsible for the cell wall of fungi?
Which structure is primarily responsible for the cell wall of fungi?
What is the purpose of using KOH in direct microscopic examination of fungal specimens?
What is the purpose of using KOH in direct microscopic examination of fungal specimens?
Which of the following media is commonly used for fungal culture?
Which of the following media is commonly used for fungal culture?
At what temperature do most fungi thrive?
At what temperature do most fungi thrive?
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Which type of test is used to detect antigens in fungal infections?
Which type of test is used to detect antigens in fungal infections?
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What is the primary mechanism of action for Caspofungin in antifungal therapy?
What is the primary mechanism of action for Caspofungin in antifungal therapy?
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Which of the following is a hallmark diagnostic marker for invasive aspergillosis?
Which of the following is a hallmark diagnostic marker for invasive aspergillosis?
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Which antifungal agent targets the synthesis of ergosterol in the fungal cell membrane?
Which antifungal agent targets the synthesis of ergosterol in the fungal cell membrane?
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Which method would likely provide rapid results for identifying Candida infections?
Which method would likely provide rapid results for identifying Candida infections?
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Which staining method is considered the main stain for observing fungal structures?
Which staining method is considered the main stain for observing fungal structures?
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Study Notes
Lecture 14: Introduction to Medical Mycology (I & II)
- The lecture covers general properties and structure of fungi, morphology of fungi, classification of medically important fungi, human mycosis, and laboratory diagnosis of fungal infections.
- The lecture's content includes general properties, structure, morphology, classification, and human mycoses of fungi. The laboratory diagnosis of fungal infections is also discussed.
Content of the Lecture
- General properties and structure of Fungi
- Morphology of Fungi
- Classification of medically important fungi
- Human mycosis
Laboratory Diagnosis of Fungal Infections
- Specimens: Skin scrapings, hairs, nails, respiratory secretions, blood.
- Laboratory Diagnostic Tests:
- Direct microscopic examination
- Fungal culture
- Serological tests
- Skin tests
- Molecular methods (e.g., PCR)
1- Direct Microscopic Examination
- Unstained preparations (wet mount):
- For skin scrapings, nails, or hairs, add a drop of 10-30% KOH solution.
- Stained preparations:
- Lactophenol cotton blue (main stain)
- Silver stain
- Periodic acid Schiff (PAS) stain
2- Fungal Culture
- All fungi are aerobic.
- Temperature requirements:
- Most fungi: 25-27°C
- Yeasts: 37°C
- Dimorphic fungi: 25°C and 37°C
- Incubation time:
- Usually, positive cultures are obtained within 7-10 days
- Candida and Aspergillus: 24 to 72 hours
- Sabouraud's dextrose agar (SDA): Enriched and selective media for fungi, examples include Aspergillus niger and Aspergillus flavus, Mucor, and Penicillium spp., and Candida albicans.
3- Serological Tests
- Detection of antigens and antibodies:
- 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 to diagnose systemic mycosis.
Antifungal Therapy
- Mechanism of action:
- Inhibit cell wall synthesis: Caspofungin
- Inhibit ergosterol synthesis in cell membrane:
- Polyenes (e.g., nystatin, amphotericin B)
- Azoles (e.g., miconazole, fluconazole)
- DNA synthesis inhibitors: Flucytosine
Sample Questions
-
Q1: Which component is found in the cell membrane of fungi?
- Ergosterol
-
Q2: What does tinea pedis mean?
- Fungal infection of the toe web
-
Q3: Which antifungal agent inhibits nucleic acid synthesis?
- Flucytosine
-
Q4: Which organism is an example of yeast fungi?
- Candida albicans
References
- Lippincott Illustrated Microbiology 4th edition, Chapters 20.
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Description
Explore the fascinating world of medical mycology in this lecture. You will learn about the properties, structure, and classification of fungi, as well as their role in human diseases and methods for laboratory diagnosis of fungal infections. Join us for an insightful journey into the realm of fungi and their medical importance.
