staining Flashcards
what is gram negative
2 outer membranes with thin peptidoglycan
what colour is it stained
pink
not stained by cv but by safranin so pink
what is gram positive
1 outer thick membrane with peptidoglycanon outside
how to carry it out
attach bacteria to glass slide
using bacteria culture then using heat to fix it
add crytsal violet solution
add iodine
alcholol wash
counter stain with safrnain staining everything pink
what does cystal violet solution do
enter the cell wall
what does iodine form
larger complex with the cv
what does the alcohol do
dehydrates pepditogylcan layer = tightened
in gp the crystal violet and iodine can’t leave so theyre
stained with cv so are purple
gn the cv iodine complex washed out - lose cv stain
what coulour is gp
purple
the cv and iodine aren’t washed out
what are shperes called
coccus
coccus
dicooci
staphcocci
round ended cylinders
bacillus
what are hemolysins
enzymes that are released by bacteria that can damage red blood cells
hemolytic activity is useful for differentiating which species
gp
what is gamma hemolysis
g no hemoysis- no zone
alpha partial- opaque zone
b complete - transparent zone
how to test ha
growth on compplex medium containig 5% sheep red blood cells
shows if the b produces hemolysins
lactose fermantation is useful to diff gn
yes - if it can use lactose for growth
how is it done
growth on macconkey agar conatinig bile salts cv and lactose
using ph indicator
overnight
why can’t gp grow
bile salts inhibit growth
Define lactose fermenting
and what colour
bacteria produce acid during lactose fermentation
they have enzyme lactase
producing lactic acid
I^ acidity = determine if lactose fermenting
pink
what is lactose non fermentar
and what colour
don’t ferent lactose
shown as yellow
what is the catalse dest
determines whether catalase is produced (enzyme catalysing breakdown of h2o2 to o2 n h20)
diff between staphylococci - producing catalse
strephtococci don’t produce catalase
diff between gp
how do you know if catalse is present
o2 bubbles
from h2o2 breakdown
how
bacteria ad to glass slide
add h2o2
if bubbles are produces
what is coagulase test
determines whether bateria produces coagulase enzyme that cross links fibrinogen in plasma to clot
what do they diff between
staphylococci- do not produce coagulase
s aures - coagulase produced
how to tell if
clumps = coagulase
how
add bacteria to glass slide
add plasma
incubate 15 seconds gently rotate
genration of clumps
