Micro 2 Flashcards
(31 cards)
Grams iodine is considered a
Mordant
The 4 reagents used to perform a gram stain
Crystal violet
Grams iodine
Decolorizer
Safranin
What is a mordant
Helps cause a chemical reaction between stain and bacteria. Helps it stick
Decolorizer could be 2 things
Acetone or alcohol
Safranin is considered
Carbol fuschin
Why do gram pos and gram neg stain differently
Bc of the amt of peptidoglycan in the cell wall
Peptidoglycan consists of
Sugar and amino acids
What bacteria has high affinity for violet stain and stains purple
Gram pos
Gram pos stains ____ gram neg stains _____
Pos- purple
Neg- pink or red
Gram pos vs gram neg
Gram pos- thicker cell wall, thicker layer of peptidoglycan.
Gram neg- thinner ^. Outer lipopolysaccharide layer (LPS)
Outer lipopolysaccharide layer makes gram neg resistant to
Abx
3 basic forms of bacteria
Coccus, bacillus, spirillium
Staphylococci vs streptococci
Staph- grape like cluster
Strept- chain like
Sarcina
Cube shape- 8 stacked
Crystal violet precipitate on epithelial cell may be confused with
Gram pos cocci
If cells are all purple
May be under decolorized
If cells are all pink
May be over decolorized
How you know it’s stained properly
Pink nuclei and cytoplasm
Normal psittacine stool (mute) consist of
95% gram pos rods and cocci. 5% gram neg rods
Is yeast normal in birds
Occasionally
Acid fast stain is a differential stain that distinguishes organisms with
Waxy cell walls (mycolic acid)
Acid fast stain usually resist
Decolorization with acid alcohol
Mycobacterium paratuberculosis
Affects cattle, johne’s dz
Mycobacterium bovis
Affects cattle- TB. Zoonotic
