Description
Use and description:
Basic medium for Blood Agar, for isolation and cultivation of fastidious bacteria and for detection of haemolytic activity of streptococci and other microorganisms. Completed medium is prepared with 5 to 10% blood. Blood Agar Base can be used as general purpose medium for the cultivation of a wide range of microorganisms.
Composition per litre:
Peptone……………………………….…….10.0 g
Beef extract………………………………..10.0 g
Sodium chloride……………………..…….5.0 g
Agar……………………………………………12.0 g
Final pH of the ready to use medium: 7.4 ± 0.2
Medium preparation:
Add 37.0 grams of dehydrated culture medium to 1 litre of distilled water. Mix thoroughly. Heat with frequent agitation and boil for 1 min to completely dissolve. Autoclave for 15 min at 121 ⁰C. Cool to 45-50 ⁰C. Aseptically add 5-10% of sterile, defibrinated blood. Mix thoroughly and pour into sterile Petri dishes.
Quality specifications:
Dehydrated medium: homogeneous, light beige fine powder.
Ready to use medium: opaque and cherry red when supplemented with blood.
Microbiological response at 37 ⁰C after 18-24 hours:
| Organism | Result | Haemolysis |
| Staphylococcus aureus ATCC 25923 | Growth | Beta |
| Streptococcus pneumoniae ATCC 6305 | Growth | Alpha |
| Streptococcus pyogenes ATCC 19615 | Growth | Beta |
Storage:
Dehydrated medium should be stored between 10 to 25 ⁰C. Once opened, place the container in a dark, dry place. The dehydrated medium should not be used if there is any lump or if the colour has changed from the original.