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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?
- Cellulose
- Phospholipids
- Chitin (correct)
- Lignin
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?
- To culture fungi
- To clear the specimen for better visibility (correct)
- To stain the specimen
- To preserve the specimen
Which of the following media is commonly used for fungal culture?
Which of the following media is commonly used for fungal culture?
- Nutrient agar
- MacConkey agar
- Blood agar
- Sabouraud's dextrose agar (correct)
At what temperature do most fungi thrive?
At what temperature do most fungi thrive?
Which type of test is used to detect antigens in fungal infections?
Which type of test is used to detect antigens in fungal infections?
What is the primary mechanism of action for Caspofungin in antifungal therapy?
What is the primary mechanism of action for Caspofungin in antifungal therapy?
Which of the following is a hallmark diagnostic marker for invasive aspergillosis?
Which of the following is a hallmark diagnostic marker for invasive aspergillosis?
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?
Which method would likely provide rapid results for identifying Candida infections?
Which method would likely provide rapid results for identifying Candida infections?
Which staining method is considered the main stain for observing fungal structures?
Which staining method is considered the main stain for observing fungal structures?
Flashcards
Medical Mycology
Medical Mycology
The study of fungi, including their characteristics, classification, and their interactions with humans and other organisms. It plays a crucial role in understanding fungal infections and developing effective treatments.
Fungus
Fungus
A eukaryotic organism that thrives in diverse environments, often decomposing organic matter. They play vital roles in ecosystems, but some can cause infections in humans.
Morphology of Fungi
Morphology of Fungi
The shape and form of a fungus, often used for identification. Fungi can exist as single-celled yeasts, filamentous molds, or a combination.
Human Mycosis
Human Mycosis
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Laboratory Diagnosis of Fungal Infections
Laboratory Diagnosis of Fungal Infections
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Specimens for Fungal Diagnosis
Specimens for Fungal Diagnosis
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Direct Microscopic Examination
Direct Microscopic Examination
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Fungal Culture
Fungal Culture
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Serological Tests
Serological Tests
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Antifungal Therapy
Antifungal Therapy
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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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