Quiz On Acid Fast Spore Stains And Decarboxylase Flashcards
What is the cytological basis for the acid fast differential stain?
Mycolic acids in the cell wall of acid fast organisms
What is mycolic acid?
A waxy substance that gives acid fast cells a higher affinity for the primary stain and resistance to decolorization by an acid alcohol
Two examples of acid fast staining procedures
Ziehl- neelsen ( zN)
And
Kinyoun (k)
Difference between the ZN method and the K method of acid fast stain
Zn uses heat as part of the staining process whereas K is a cold stain
What is the primary stain of an acid fast stain?
Carbolfuchsin
What does the waxy wall of acid fast cells do to aqueous stains?
Typically it repels them making them only weakly gram-positive
What type of cell is an acid fast stain trying to detect
Cells capable of retaining a primary stain when treated with an acid alcohol
What is used as the decolorization in an acid fast stain?
Acid alcohol
What is the counter stain used in an acid fast stain?
Methylene blue or brilliant green
What color are acid fast and acid fast negative cells prior to staining in an acid-fast stain
Both are transparent
After staining with carbolfuchsion in an acid fast stain
Both acid fast and acid fast negative are reddish purple
What color is acid fast and acid fast negative after decolorization in an acid fast stain
Acid fast is reddish purple
Acid fast. Negative is transparent
What color is acid fast and acid fast negative after the counter stain in an acid fast stain
Acid fast is reddish purple
Acid fast negative is blue or green
What is an endospore?
A dormant cell that forms in environmental conditions such as nutrient depletion or high temperatures that are unsuitable for growth
Are endospores resistant to heat and chemicals?
Yes, so they can live in this state for long periods of time
Is there ATP within an endoscore
No
What two factors are sporulation dependent on?
Nutrient depletion and population density
How does population density affect endospore generation and how does it work
With increased density a secreted peptide called a competence and sporylation factor ( CSF) reaches a critical concentration and results in sporrelation genes starting
What is an endosports tough outer covering made of?
keratin
When conditions are suitable again for growth, what happens to endospores?
They germinate into metabolically active vegetative cells
What happens when you try and stain an endospore?
It’s Spore coat resist staining because of the keratin
What is a spore mother cell?
A cell responsible for producing the endospore
What are the three locations of an endospore in a cell?
Middle of the cell called Central
End of the cell called terminal
Between the end and middle of the cell called subterminal
Is a. Spore always in the same location
No in some species. The location is variable
How can endospores be differentiated?
With their shape either spherical or elliptical( oval)
And the spores shape relative to the size of the cell
Color of Spore producing cells and non-spore producing cells prior to staining
Spore producing cells are transparent
Non-spore producing cells are also transparent
After staining with the primary stain of malachite green and with heat, what color are the cells?
Spore producing cells are green all the way through
Non-spore producing cells are green all the way through
After decolorization with water, what color are cells in an endospore stain?
Spore producing cells are transparent with a green Center
Non-spore producing cells are transparent
After safrinin is used as a counter stain in an endospore stain, what color are the cells?
Spore producing cells are red with a green Center
Non-sport producing cells are red all the way through
What is the primary stain in an endospore stain
malachite green
What is the decolorizer in an endosport stain
Water
What is the counter stain in an endospore stain?
Safranin
A type of bacteria that typically makes spores
Bacillus
What four things do mollers decarboxylase medium contain?
Peptone
Glucose
The pH. Indicator bromocresol purple
And the coenzyme pyridoxal phosphate
At what pH is bromocresol purple actually purple And when is it yellow?
6.8 or above it’s purple
It’s yellow at pH 5.2 or below
After inoculation what is used to seal the medium from external oxygen and promote fermentation
An overlay of mineral oil
What does glucose fermentation do to the color?
In the anaerobic medium initially it turns yellow because of the accumulation of acid end products
The low pH and presence of the specific amino acid induces what
Decarboxylase positive organisms to produce the enzyme meaning that the gene is switched on
Decarboxylation of the amino acids results in what?
The accumulation of amines which are alkaline and then turn the medium purple
If the organism is a glucose fermenter but does not produce the appropriate decarboxylase, what color does it turn?
Yellow and remains so
If the organism does not ferment glucose, what color does it turn?
The medium will exhibit no color change
What is the only positive result in color for decarboxylation
Purple all other colors are negative
What are the three amino acids tested most frequently for decarboxylase activity
Arginine
Lysine
Ornithine
What is the dihydrolase system?
A second pathway for arginine catabolism
In this system. Arginine is converted to citrulline and then into ornithine
ATP CO2 and two NH3 raises the pH and then turns the medium purple
If the species is also positive for orthanine decarboxylase it will produce putrescine and CO2 from ornithine
Decarboxylase media can include one of several amino acids. Typically these media are used to differentiate what
Organisms in the family enterobacteriacae and to distinguish them from other gram-negative rods
