Podcast
Questions and Answers
Which type of test is primarily used for direct visualization of fungi?
Which type of test is primarily used for direct visualization of fungi?
At what temperature do the majority of fungi grow best?
At what temperature do the majority of fungi grow best?
Which laboratory method is specifically diagnostic for invasive aspergillosis?
Which laboratory method is specifically diagnostic for invasive aspergillosis?
What is the main purpose of Sabouraud's dextrose agar in fungal culture?
What is the main purpose of Sabouraud's dextrose agar in fungal culture?
Signup and view all the answers
Which antifungal agent works by inhibiting cell wall synthesis?
Which antifungal agent works by inhibiting cell wall synthesis?
Signup and view all the answers
When would you typically expect a fungal culture to yield a positive result?
When would you typically expect a fungal culture to yield a positive result?
Signup and view all the answers
Which of the following is not a method of laboratory diagnostic testing for fungal infections?
Which of the following is not a method of laboratory diagnostic testing for fungal infections?
Signup and view all the answers
Which staining method is considered the main stain for fungal microscopic examination?
Which staining method is considered the main stain for fungal microscopic examination?
Signup and view all the answers
What role does ergosterol play in fungi?
What role does ergosterol play in fungi?
Signup and view all the answers
What does the detection of specific antibodies in blood samples indicate?
What does the detection of specific antibodies in blood samples indicate?
Signup and view all the answers
Study Notes
Medical Mycology Lecture 14
- The lecture covers an introduction to medical mycology (I & II)
- The lecture will cover general properties and structure of fungi, morphology of fungi, classification of medically important fungi, and human mycoses.
- The lecture will also cover laboratory diagnosis of fungal infections, including specimens (skin scrapings, hairs, nails, respiratory secretions, blood), and diagnostic tests (direct microscopic examination, fungal culture, serological tests, skin tests, molecular methods like PCR).
- KOH preparation (10-30%) is used for unstained preparations (wet mount) of skin scrapings, nails, or hairs to view fungal elements under a microscope.
- Stained preparations use Lactophenol cotton blue (main stain), Silver stain, and Periodic acid Schiff (PAS) for further analysis.
Laboratory Diagnosis of Fungal Infections
- Specimens are selected based on the site of infection. Common examples include skin scrapings, hairs, nails, respiratory secretions, and blood.
- Diagnostic tests include direct microscopic examination, fungal culture, serological tests, skin tests, and molecular methods like PCR.
- Direct microscopic examination includes unstained preparations (KOH wet mounts) and stained preparations (e.g., Lactophenol cotton blue, Silver stain, PAS).
Fungal Culture
-
All fungi are aerobic.
-
Temperature requirements vary:
- Most fungi: 25-27°C (superficial)
- Yeast: 37°C
- Dimorphic fungi: 25°C and 37°C
-
Incubation times:
- Positive cultures usually obtained in 7-10 days
- Some fungi (Candida & Aspergillus) at least 4 weeks or 24 to 72 hours.
-
Sabouraud's dextrose agar (SDA) is a selective and enriched media for fungi.
-
Examples of fungi that can be grown on SDA include Aspergillus niger, Aspergillus flavus, Mucor, and Penicillium spp., and Candida albicans.
Serological Tests
- Detection of antigens and antibodies is used for diagnosis.
- β-D-glucan detection from blood samples is diagnostic of invasive fungal infections.
- Galactomannan detection in blood samples is diagnostic for invasive aspergillosis.
- Antibody detection is used to diagnose systemic mycosis.
Antifungal Therapy
- Mechanisms of action of antifungal drugs include:
- Inhibiting cell wall synthesis (e.g., Caspofungin)
- Inhibiting ergosterol synthesis in cell membrane (e.g., polyenes: nystatin & amphotericin B, azoles: miconazole & fluconazole)
- Inhibiting DNA synthesis (e.g., Flucytosine)
Clinical Questions
- Ergosterol is a component of the fungal cell membrane.
- Tinea pedis is a fungal infection of the toe webs.
- Flucytosine inhibits nucleic acid synthesis.
- Candida albicans is an example of a yeast fungus.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
This lecture introduces the key aspects of medical mycology, exploring the properties, structure, and classification of fungi. It also focuses on the laboratory diagnosis of fungal infections, including specimen selection and diagnostic methods such as KOH preparation and various staining techniques. Enhance your understanding of human mycoses and the tools used for effective diagnosis.
