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Blood Agar Plate (BAP)
Transcript of Blood Agar Plate (BAP)
Form: bright red gel and opaque medium
Purpose: BAP contains 5 % sheep blood and is used to identify bacteria that produce hemolytic ( blood cutting ) enzymes, known as exotoxins called hemolysins. as well it is used for the growth of fastidious bacteria. Bacteria that grow on the BAP will produce one of the three hemolytic patterns : Alpha
Gamma It is easiest to interpret the difference between the three different types : Using usual procedures where we look at the above culture. Well NO !!
We flip the culture upside down and look at the below effects. How ?? The Shape and process of identification of the three types Gamma Hemolysis Although there was growth on the top side, but in the lower side no change Alpha Hemolysis Normal flora On the bottom side we see brownish color or brused Normal Flora Beta Hemolysis Keep in mind these are all throat samples Where we see three bloobs where the medium has completely lost its color and become transparent, due to complete digestion of the hemolytis enzymes i the pathogenetic bacteria Since we took a throat sample, this type of beta hemolysis bacteria is known as Streptococcus pyogenes, but keep in mind this one type of beta hemolysis there are several Streptococcus pyogenes is a Gram-positive round shaped bacteria that causes beta-hemolysis on blood agar. Can we only test gram positive bacteria ? NO! This grayish spot is the gram negative bacteria while the gram positive bacteria totally transparent What is Blood Agar made of and how do we make it ? Constituents : Typical Formula* gm/litre
Peptone Neutralised 4.5
Yeast extract 4.5
Sodium chloride 5.0
Final pH 7.3 ± 0.2 @ 25°C 1.Weigh 40g of Tryptic Soy Blood Agar Base (TSBA).
2.Suspend the measured TSBA into 500 ml of distilled water.
3.Mix thoroughly (dissolving occurs during autoclaving).
4.Autoclave at 121°C for 15 minutes.
5.Allow the autoclaved TSBA to cool to 45-50°C and then aseptically add 25ml of sterile 5% sheep blood. Mix thoroughly.
6.Arrange the petri-dishes onto the clean safety hood and then gently pour the warm blood agar onto the plates.
7.Using a bunsen burner gently invert and pass the flame over the poured blood agar in the plate such that the air bubbles are removed.
8.Cover the petri-dishes and allow the blood agar to coagulate before storage in a refrigerator.
9.Label on the bottom top of the blood agar plates the batch number, date prepared and expiration date, and tech. initials. Procedure : References: Other types of Blood agar : 1- Chocolate agar a type of blood agar plate in which the blood cells have been lysed by heating the cells to 56 °C. Chocolate agar is used for growing respiratory bacteria, such as Haemophilus influenzae. No chocolate is actually contained in the plate. 2- Horse blood agar: a type of blood enriched microbiological culture media, similar to the one i explained 3- Thayer-Martin agar: a chocolate agar designed to isolate Neisseria gonorrhoeae. 4- Thiosulfate-citrate-bile salts-sucrose agar : enhances growth of Vibrio spp., including Vibrio cholerae  1.http://www.lscc.edu/faculty/james_stevens/Documents%20%20Downloads/Micro%20Lab%20Documents/Lab_7_Hemolysis_and_Blood_Agar.pdf