Question
The usual concentration of blood used for the medium represented in the picture below is?
A. 10%.
B. 20%.
C. 30%.
D. 40%.
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Correct Answer » A Explanation |
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Ans:A. 10%.
The medium shown in the picture above is Blood agar.
Blood Agar
- Blood agar plate (BAP) contains mammalian blood (usually sheep or horse), typically at a concentration of 5-10%.
- BAP are enriched, differential media used to isolate fastidious organisms and detect haemolytic activity.
- Beta-hemolytic activity will show lysis and complete digestion of red blood cell contents surrounding colony. Examples include Streptococcus haemolyticus.
- Alpha-hemolysis will only partially lyse (the cells are either lysed or not- it is the digestion that may be incomplete) the hemoglobin and will appear green or brown (due to the conversion hemoglobin to methemoglobin). An example of this would be Streptococcus viridans.
- Gamma-hemolysis (or non-hemolytic) is the term referring to a lack of hemolytic activity.
- Contains meat extract, tryptone, sodium chloride and agar.