COAs

Ingredients:
Proteose Peptone (g/L) 15.00a
Liver Extrate (g/L) 2.50
Yeast Extract (g/L) 5.00
Sodium Chloride (g/L) 5.00
Agar (g/L) 12.00
Final pH (at 25°C) 7.4 +/- 0.2

Instruction for use:
Suspend 19.75 gr in 500 ml. distilled
water. Boil to dissolve the medium completely. Sterilize by
autoclaving at 15 lbs pressure (121° C) for 15 minutes.
Cool to 40 – 50 °C and aseptically add 7% v/v sterile
defibrinated blood.

Principle :
Blood Agar Base formulations have been prepared using specially selected raw materials to support good
growth of a wide variety of fastidious microorganisms.
Proteose Peptone is the nitrogen source for Blood Agar Base No. 2 while Yeast Extract and Liver Digest
provide essential carbon, vitamin, nitrogen and amino acids sources. It contains Sodium Chloride to
maintain osmotic balance and Agar as a solidifying agent. Blood Agar Bases are relatively free of reducing
sugars, which have been reported to adversely influence the hemolytic reactions of beta-hemolytic
streptococci.
Supplementation with blood (5-10%) provides additional growth factors for fastidious microorganisms and
is the basis for determining hemolytic reactions. Hemolytic patterns may vary with the source of animal
blood or type of base medium used. Chocolate agar for isolating Haemophilus and Neisseria species can
be prepared from blood agar base No. 2 by supplementing the medium with 10% sterile defibrinated blood
(chocolatized).