Questions and Answers
What type of hyphae grow above the surface of the media and carry spores?
At what temperature do yeast forms of fungi occur?
Which type of reproduction involves the union of two nuclei?
Which type of mycosis is characterized by an infection in the lungs?
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What is the main method of reproduction in moulds?
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What is the correct classification for a fungal infection caused by Candida?
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What type of fungi can exist in both yeast and hyphal forms?
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What is a characteristic of systemic mycosis?
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Which component is found in the cell wall of fungi?
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What type of reproduction can fungi undergo?
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Which of the following fungi are unicellular in nature?
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What is the optimum temperature range for most fungi?
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Which of the following is true regarding fungal metabolism?
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What characteristic separates dimorphic fungi from other types?
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What pH range do most fungi prefer for growth?
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Which of these is an example of a yeast?
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What is the primary purpose of using SDA + Chloramphenicol + Cyclohexamide in fungal culture?
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What kind of method is used with Woods light for clinical diagnosis?
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Which sample types are necessary for diagnosing fungal infections based on their site?
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Which of the following is a characteristic of mycetoma?
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Which factor is NOT a predisposing factor for fungal infections?
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Which type of fungi is associated with endemic source of infections?
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What does serological diagnosis like ELISA detect?
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What is the primary source of endogenous infections in fungal diseases?
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Study Notes
Fungal Characteristics
- Fungal cell wall consists of glucan and chitin.
- Cell membrane contains sterols.
- Classifications include yeasts, molds, yeast-like, and dimorphic fungi.
Reproductive Mechanisms
- Fungi reproduce both sexually (fusion of nuclei) and asexually (fragmentation and budding).
Fungal Metabolism
- Aerobic fungi require oxygen; facultative anaerobes can survive in both conditions.
- Optimal growth temperature is 25-30 ºC, aligning with their saprophytic nature.
- Fungi thrive in a wide pH range (2-9), generally preferring acidic conditions.
Yeasts
- Unicellular and typically rounded or oval in shape.
- Reproduce by budding, with daughter cells remaining attached to form pseudohyphae.
- Examples include Cryptococcus neoformans and Candida.
Molds
- Filamentous fungi characterized by septated or non-septated hyphae.
- Two types of hyphae: vegetative (penetrate media) and aerial (above surface, carry spores).
Dimorphic Fungi
- Exist in two forms: yeast and hyphal.
- Yeast form occurs at body temperature (37 ºC) and during infections.
- Example includes Histoplasma capsulatum.
Classification of Mycosis
- Mycosis is classified based on the infecting organism, such as:
- Candidiasis - infection by Candida.
- Aspergillosis - infection by Aspergillus.
- Cryptococcosis - infection by Cryptococcus.
- Histoplasmosis - infection by Histoplasma.
- Alternatively, it can be classified by the site of infection, such as pulmonary mycosis.
Types of Human Mycosis
- Superficial mycosis - affects the uppermost skin layer.
- Cutaneous mycosis - impacts skin, mucosal surfaces, hair, and nails.
- Subcutaneous mycosis - involves implantation of spores into wounds.
- Systemic mycosis - affects multiple organ systems.
- Opportunistic mycosis - occurs in immunocompromised hosts.
Transmission Methods
- Common methods of transmission include inhalation of spores and local spread of mycosis.
Diagnosis of Fungal Infections
- Sample collection is determined by the infection site: skin, hair, or nails.
- Direct microscopic preparations involve unstained (KOH) and stained (Lactophenol cotton blue) methods for identification.
- Culture techniques include using Sabouraud's dextrose agar and its modified forms.
- Use of Woods light helps diagnose by producing fluorescent colors in affected areas.
- Serological methods, such as ELISA, are utilized for indirect diagnosis.
Sources of Infection
- Endogenous infections arise from normal flora in the oral cavity, gastrointestinal tract, female genital tract, and skin.
- Exogenous infections typically occur through sexual contact.
Predisposing Factors
- Susceptibility increases due to extremes of age, immunosuppression (e.g., pregnancy, diabetes).
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Description
Explore the fundamentals of Medical Mycology, focusing on the cellular structures of eukaryotic organisms such as yeasts, molds, and dimorphic fungi. This quiz covers key components like cell walls and membranes that are crucial for understanding fungal biology in a medical context.
