Bacteria Intro Gram staining technique Infectious Disease Ch1 P1
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hello and welcome back to another future doc
house production I’ve decided to write my own clinical microbiology review book it’s
called medicine the ultimate guide clinical microbiology a quick review by yours truly
future doc house if you would like this is only the first chapter if you would like the
first chapter emailed to you please find me on facebook or instagram or twitter or whatever
social media platform you are currently using google search for future D O C doc house and
I will give me your email address and I will send you a copy of what I’ve written alright
these lectures are free this material that I email to you is free I hope you enjoy it’s
for educational purposes and lets start lets talk about chapter one alright chapter one
bacteria introduction lets talk about the introduction of bacteriology and if we are
going to talk about microbiology we need to talk about Robert Hermann Koch he is a very
famous person you will see many things named after him so be aware of this name in nineteen
sorry eighteen ninety he made four postulates he published four postulates to prove a causative
relationship between microorganism and disease now in order to prove that there is a causative
relationship between a microbe and a disease you need to prove these things one the microbe
must be found in abundance in the disease organism and not found in the healthy organism
two the microbe must be isolated and cultured three the cultured microbe should be inoculated
into a healthy organism and cause a that healthy organism to get diseased become diseased four
the microbe should be re isolated from the inoculated organism and cultured so once these
things are proven these postulates are proven then you can establish that this microbe microorganism
is in fact the cause of the disease alright the fun stuff gram staining technique fixation
when you do a swab so you swab a throat ok you put that swab sample on to a slide and
you fix it onto the slide usually through a Bunsen burner by burning it onto the slide
two crystal violet crystal violet is a bluish stain and you would do fifty five to sixty
seconds and this is how you would give enough time for the dye to soak into the cell wall
or cell membrane of the bacteria say if you swab the throat and you are looking for streptococcus
ok two three rinse with deionized water four add iodine five rinse with deionized water
six add alcohol or acetone now why do we add alcohol or acetone alcohol or acetone basically
decolorizes it decolorizes the stain removes the stain removes the crystal violet and this
helps us separate which bacteria is gram positive and which bacteria is gram negative and then
you counterstain now you add a different color stain which is safranin which is a red color
stain hence why it’s in red rinse with deionized water again and you look under the microscope
you put it on under the microscope table look through the microscope see what color it is
see what types shape sizes the microorganism is most likely it is a bacteria hence through
gram staining and if the bacteria shows up as blue or purple color then the bacteria
is a gram positive bacteria if the bacteria shows up as a reddish color or pinkish color
it’s a gram negative bacteria now why do we know the difference that there is two different
types of bacteria based off of gram staining well gram positive bacteria has a thick cell
wall with a lot or extensive crosslinking amino acids now the extensive crosslinking
of the amino acids and this thick cell wall absorbs the crystal violet and all these processes
afterwards especially the decolorization of alcohol or acetone does not remove the color
and if it does not remove the color and if it does not remove the crystal violet color
from the bacteria its shows up as blue or purple but if it a gram negative bacteria
it has a thin cell wall the cell wall is much thinner and it has a simple lining pattern
linear pattern between the amino acids now the stain the crystal violet stain that is
staining the cell membrane can be easily washed off by the alcohol or acetone because there
is no cross linking it just a linear pattern and if you wash off and re-stain with safranin
ok and that’s why it shows up as red now be careful gram staining can give you gram positive
and gram negative bacteria but there is also a family of bacteria that don’t stain or very
poorly stains a gram positive or gram negative color a blue or red color and we will talk
about that in the next video so if you like this video and you want more of these videos
please click subscribe thank you and have a nice day

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