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Questions and Answers
Which components are present in the fungal cell wall?
Which components are present in the fungal cell wall?
What type of reproduction do fungi exhibit?
What type of reproduction do fungi exhibit?
What is the optimum temperature range for most fungi?
What is the optimum temperature range for most fungi?
What is one of the common characteristics of yeast?
What is one of the common characteristics of yeast?
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Which of the following statements about fungal metabolism is incorrect?
Which of the following statements about fungal metabolism is incorrect?
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What defines dimorphic fungi?
What defines dimorphic fungi?
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What is a characteristic of the cell membrane in fungi?
What is a characteristic of the cell membrane in fungi?
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Which statement is true regarding the pH preference of fungi?
Which statement is true regarding the pH preference of fungi?
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What type of hyphae penetrate the media?
What type of hyphae penetrate the media?
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Which form do dimorphic fungi take at room temperature?
Which form do dimorphic fungi take at room temperature?
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What is a common method of asexual reproduction in fungi?
What is a common method of asexual reproduction in fungi?
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What type of mycosis occurs in an immunocompromised host?
What type of mycosis occurs in an immunocompromised host?
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Which fungal infection is caused by Candida?
Which fungal infection is caused by Candida?
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What type of hyphae grow above the surface of media?
What type of hyphae grow above the surface of media?
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Which form of fungi occurs during infection in the body?
Which form of fungi occurs during infection in the body?
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What is an example of a systemic mycosis?
What is an example of a systemic mycosis?
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What is the primary purpose of using SDA + Chloramphenicol + Cyclohexamide in fungal culture?
What is the primary purpose of using SDA + Chloramphenicol + Cyclohexamide in fungal culture?
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Which of the following materials can be used for direct microscopic preparation in diagnosing fungal infections?
Which of the following materials can be used for direct microscopic preparation in diagnosing fungal infections?
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What is the role of Woods light in the diagnosis of fungal infections?
What is the role of Woods light in the diagnosis of fungal infections?
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What is primarily used to diagnose candidal infections through serological methods?
What is primarily used to diagnose candidal infections through serological methods?
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Which type of infection is classified as endogenous?
Which type of infection is classified as endogenous?
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What is the significance of using blood agar in fungal cultures?
What is the significance of using blood agar in fungal cultures?
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Which of the following is a common predisposing factor for fungal infections?
Which of the following is a common predisposing factor for fungal infections?
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What type of fungi does Mycetoma primarily involve?
What type of fungi does Mycetoma primarily involve?
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Study Notes
Fungi Overview
- Fungi are eukaryotic organisms characterized by a cell wall made of glucan and chitin, and a cell membrane containing sterols.
- Categories of fungi: Yeasts, Molds, Yeast-like fungi, and Dimorphic fungi.
Reproductive Methods
- Fungi reproduce both sexually (involving the union of two nuclei) and asexually (mainly through fragmentation, budding).
- Asexual reproduction includes budding in yeasts, producing pseudohyphae (e.g., Candida).
Fungal Metabolism
- Oxygen Requirement:
- Aerobic: All fungi require oxygen.
- Facultative anaerobes: Some fungi can grow without oxygen.
- Optimal Growth Temperature: 25 – 30 ºC, suitable for saprophytic fungi.
- pH Tolerance: Prefer a wide range of pH (2 – 9), usually favoring acidic conditions.
Fungal Classification
-
Yeasts:
- Unicellular, round or oval shape, reproduce by budding.
- Examples include Cryptococcus neoformans and Candida species.
-
Molds (Filamentous fungi):
- Hyphae can be septated or non-septated; vegetative and aerial hyphae present.
-
Dimorphic Fungi: Display two forms (yeast and hyphae) depending on growth conditions.
- Hyphae occur at room temperature, while yeast forms appear at 37 ºC during infections.
- Example: Histoplasma capsulatum.
Naming of Mycosis
- Names generally derived from the organism causing the infection:
- Candidiasis: Caused by Candida.
- Aspergillosis: Caused by Aspergillus.
- Cryptococcosis: Caused by Cryptococcus.
- Histoplasmosis: Caused by Histoplasma.
- Further classified by infection site:
- Types: Superficial, Cutaneous, Subcutaneous, Systemic, Opportunistic.
Diagnosis of Fungal Infections
- Sample collection based on infection site: skin, hair, or nails.
- Microscopic Preparation:
- Unstained: KOH (10 – 30%).
- Stained: Lactophenol cotton blue.
- Culture Techniques:
- Use Sabouraud's Dextrose Agar (SDA) for fungal growth, often supplemented with chloramphenicol and cyclohexamide to inhibit bacteria.
- Blood agar is used for fastidious dimorphic fungi.
Diagnostic Methods
- Woods Light: Utilizes ultraviolet rays to identify fluorescence in mycotic areas.
- Indirect Diagnosis: Serological tests such as ELISA for candidal infections.
Sources and Predisposing Factors
- Endogenous Source: Fungi are normal flora found in the oral cavity, GIT, and skin; they can lead to opportunistic infections.
- Exogenous Source: Infection may occur through sexual intercourse.
- Predisposing Factors:
- Age extremes, immunosuppression, pregnancy, and diabetes increase risk of infection.
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Description
Explore the fundamental concepts of medical mycology, focusing on eukaryotic microorganisms such as yeasts and molds. Delve into cellular structures including cell wall components like glucan and chitin, and the significance of sterols in cell membranes.
