staining procedures Flashcards
simple staining
Involves the use of a single stain to visualize morphological characteristics such as shape and arrangement.
stain
a dye that is a salt
basic stain
When the chromophore is attached to the positive end, and attracted to the negative end of bacteria
acidic stain
when the chromophore is attached to the negative end.
T/F basic stain requires heat fixation of the bacteria on the slide
T
what consistency should your bacteria and water have on your slide?
skim milk consistency
in gram positive bacteria, where does the external negative charge come from?
lipoteichoic acid
in gram negative bacteria, where does the external negative charge come from?
lipopolysaccharide (LPS)
during a basic stain, how long should you leave your dark stain on for?
1 minute
during a basics stain, how long should you leave your light stain on for?
2 minutes
acidic stain
when the chromophore attached to a negative end.
what will the bacteria look like during a basic stain?
colored bacteria on a light background
what will the bacteria look like during an acidic stain?
light bacteria on a dark background
is there heat fixation during an acidic stain?
no
which stain is better to see shape of the bacteria? why?
acidic stain, there is no heat fixation and easier to see on a dark background
what does the 95% ETHOL do to the gram negative bacteria?
weakens the outer membrane, dye seeps through holes (clear)
what does the 95% ETHOL do to the gram positive bacteria?
slightly dehydrates the cell and locks in the stain (still purple)
examples of basic stains?
methylene blue, crystal violet
examples of acidic stains?
nigrosine, india ink
in a differential stain, what stain do you add after you wash your plate with 95% ETOH? how long?
safranin stain, 2 minutes
at the end of a differential stain, what colors are your gram negative and gram positive bacteria?
gram neg: pink (light)
gram pos: stays purple (dark)
what are acid fast stains used for?
mycobacteria
do you heat fixate for acid fast stain?
yes
what is the primary stain for acid fast stain?
carbolfuchsin (dark red stain)
what is carbolfuchsin made of? what does it do?
5% phenol, helps penetrate the hydrophobic membrane
in an acid fast stain, is the 5% phenol enough to penetrate the membrane?
no
what methods are used in acid fast stains to help penetrate the membrane?
ziehl-neelson method and kinyoun method
what is the ziehl neelson method?
use steam as heat.
during the ziel neelson method why do you need to use a vent hood?
Because phenolic fumes are being created.
what is the kinyoun method?
use carbolfuchsin and add a wetting agent. keep adding wetting agent (tergital) on for 5 minutes
for the acid fast stain, what is used as the decolorizer?
95% ETOH
what color does the acid fast stain as?
red
what color does the non-acid fast stain as?
no color
do you need a counter stain in acid fast stain? if so, what?
yes, methylene blue
what is the primary stain for the schaeffer (endospore) staining?
malachite green
do you need a counter stain for the schaeffer (endospore) staining?
yes, use safranin
