IB. Medical Mycology | 23. Microbiological diagnosis of diseases caused by fungi. Flashcards
What is mycosis?
mycosis= infection caused by fungi
I. Laboratory diagnosis of fungal diseases
1. What are the methods of Laboratory diagnosis of fungal diseases?
- Culture
- Microscopy
- Biochemical Reactions
- Serology
- Molecular biology
- MALDI - TOF
- FISH
- E test
I. Laboratory diagnosis of fungal diseases
2. What are the specimens we need to prepare for Laboratory diagnosis of fungal diseases?
- scrapings from the skin and the nails
- hairs plucked from involved areas
- Microsporum-infected hairs fluoresce under Wood’s light (365 nm) in a darkened room
I. Laboratory diagnosis of fungal diseases
2. Why do we need culture for Laboratory diagnosis of fungal diseases?
the identification of dermatophyte species requires cultures
I. Laboratory diagnosis of fungal diseases
3A. How do we use CULTURE in Laboratory diagnosis of fungal diseases?
- specimens are inoculated onto inhibitory mould agar or Sabouraud’s agar plates containing cycloheximide and chloramphenicol
- species are identified on the basis:
- colonial morphology (growth rate,
surface texture, and any pigmentation)
- microscopic morphology (macroconidia, microconidia)
- nutritional requirements - long time incubation (for negative result) - about 14 days
I. Laboratory diagnosis of fungal diseases - CULTURE
3B. What is the basis for identification of the species?
- colonial morphology (growth rate,
surface texture, and any pigmentation) - microscopic morphology (macroconidia, microconidia)
- nutritional requirements
I. Laboratory diagnosis of fungal diseases - CULTURE
3C. What are specimens inoculated on?
specimens are inoculated onto inhibitory mould agar or Sabouraud’s agar plates containing cycloheximide and chloramphenicol
I. Laboratory diagnosis of fungal diseases
4. How do we use microscopy in Laboratory diagnosis of fungal diseases?
- WET MOUNT is a glass slide holding a specimen suspended in a drop of liquid (as water) for microscopic examination
- simple staining (eg. methylene blue)
- before native examination 30% KOH => keratolysis
I. Laboratory diagnosis of fungal diseases
5. What are biochemical reactions we can use to identify fungal diseases?
- sugar fermentation
- sugar assimilation test
- nitrate assimilation test
II. What are the 5 types of mycological diseases?
- Dermatomycoses = Superficial, cutaneous, and subcutaneous mycoses
- Systemic mycoses
- Opportunistic mycoses
- Allergic reactions
- Intoxications
III. Therapy of fungal infection
1. What are the 3 main therapies for fungal reaction?
- Polygenes
- 5-fluorocystosine
- Azoles
III. Therapy of fungal infection
2. How does Polygenes work?
- bind egosterol
- Weaken the cell membrane
- form pores
- Leakage of K+ and Na+
- Fungal cell death
- Also cause mammalian toxicity
III. Therapy of fungal infection
3. How does Azoles work?
It will inhibit the enzyme that synthesize egosterol
III. Therapy of fungal infection
4. How does 5-fluorocystosine work?
Block the synthesis of nucleic acid
III. Therapy of fungal infection
4. Make a schematic diagram for the biosynthetic pathway of ergosterol and points of activity by anti-fungal agent?