Lab2 Flashcards
Which two broad groups are fungi divided into?
Yeasts (essentially unicellular) and moulds (multicellular)
Which two broad groups are fungi divided into?
Yeasts (essentially unicellular) and moulds (multicellular)
What kind of pathogens are fungi?
opportunist pathogens
What sort of conditions do fungal spores readily proliferate in?
Warm, moist conditions like Auckland
In order to visualse moulds microscopically, they can be stained with what?
lactophenol blue or light green
Yeasts take up gram stain reagents, but cannot be described as… what? why is this?
gram positive or gram negativethis is because they are not bacteria, and their cell wall is different from bacteria
How can yeasts be easily distinguised from bacteria?
easily distinguished by sizeYeasts are eukaryotic and eukaryotic cells are generally bigger than prokaryotic cells (bacteria)
What does candida albicans look like when grown on SDA?
spherical cells similar to cocci (except they are bigger)
What happens after c. albicans growth in serum broth?
it undergoes a budding process and the buds eventually develop into long, thin extensions of the cell
What are these long and thin extensions of thecell called?
pseudohyphae. This is to distinguish them from the real multicellular hyphae of moulds
What are the main mode of vegetative growth for moulds?
The formation of long, branching filamentous structures (hyphae)
What do moulds produce for reproduction?
they form conidiophores (fruiting bodies) which contain the small round conidia (spores)
what is the diagnostic feature of candida albicans grown in serum broth?
long and thin extensions from the cell known as pseudohyphae this results from a budding process in the serum broth
What is SDA?
Sabouraud Dextrose Agar
give an example of a genus of bacteria which do not stain readily by gram stain
mycobacterium
How are these bacteria stained?
Staining of these organisms is facilitated by the application of heatonce stained, they retain dyes and resist decolourisation with acid or acid alocholthus they are known as acid fast organims
After staining, what do acid fast organisms look like?
they are NOT decolourised,they retain the carbol fuchsin primary stain and appear RED
after staining, what do non-acid fast organisms look like?
These are DECOLOURISEDThey accept the counterstain methylene blue and appear BLUE
What kind of pathogens are fungi?
opportunist pathogens
What sort of conditions do fungal spores readily proliferate in?
Warm, moist conditions like Auckland
In order to visualse moulds microscopically, they can be stained with what?
lactophenol blue or light green
Yeasts take up gram stain reagents, but cannot be described as… what? why is this?
gram positive or gram negativethis is because they are not bacteria, and their cell wall is different from bacteria
How can yeasts be easily distinguised from bacteria?
easily distinguished by sizeYeasts are eukaryotic and eukaryotic cells are generally bigger than prokaryotic cells (bacteria)
What does candida albicans look like when grown on SDA?
spherical cells similar to cocci (except they are bigger)
What happens after c. albicans growth in serum broth?
it undergoes a budding process and the buds eventually develop into long, thin extensions of the cell
What are these long and thin extensions of thecell called?
pseudohyphae. This is to distinguish them from the real multicellular hyphae of moulds
What are the main mode of vegetative growth for moulds?
The formation of long, branching filamentous structures (hyphae)
What do moulds produce for reproduction?
they form conidiophores (fruiting bodies) which contain the small round conidia (spores)
what is the diagnostic feature of candida albicans grown in serum broth?
long and thin extensions from the cell known as pseudohyphae this results from a budding process in the serum broth
What is SDA?
Sabouraud Dextrose Agar
give an example of a genus of bacteria which do not stain readily by gram stain
mycobacterium
How are these bacteria stained?
Staining of these organisms is facilitated by the application of heatonce stained, they retain dyes and resist decolourisation with acid or acid alocholthus they are known as acid fast organims
After staining, what do acid fast organisms look like?
they are NOT decolourised,they retain the carbol fuchsin primary stain and appear RED
after staining, what do non-acid fast organisms look like?
These are DECOLOURISEDThey accept the counterstain methylene blue and appear BLUE
describe the method of the zihl-neelsen staining procedure
- Fixed slide is flooded with carbol fuchsin and heated to steaming for 5 mins. Stain must not dry out due to heatat this stage both types of cells will appear red2. Slide is washed with tap water, and cells are decolourised with acid-alcohol drop by drop until the deep red appearance of the slide is reduced to pink. this takes 10-30sec* acid fast cells retain the stain and will look pink, microscopically* non acid fast cells unable to withstand treatment with acid alcohol, this results in leeching of red carbol fuschin from cell wall. They will appear colourless at this stage3. Methylene blue - counter stain is applied (2 mins) this is not taken up by acid fast cells, but the blue counter stain is absorbed by non acid fast cells. 4. Slide is washed, then blotted dry.
what accounts for the acid fast property of the mycobacterium species?
Mycobacterium have a thick cell wall, but no cell membrane so do not take up gram stain….. ?
