for isolation and cultivation of fastidious pathogenic microorganisms after addition of blood.
BLOOD AGAR BASE (INFUSION AGAR) is used for isolation, cultivation of fastidious pathogenic microorganisms after addition of blood. Blood agar base medium can also be used for primary isolation of Haemophilus species, where defibrinated sheep blood is used to enrich the medium. The cultures of Streptococci sp. are highly infective should be handled with care. Medium contains a rich nutrient base, which provides optimal growth conditions for all relevant microorganisms. Tryptone and Brain Heart infusion supplies amino acids, minerals and other essential growth factors in the medium for the growth of microorganisms. Sodium chloride maintains the osmotic balance of the medium. Agar is a solidifying agent. On addition of blood the pH value of 6.8 stabilizes and favours the formation of clear hemolysis zones. Fresh, defibrinated sheep blood is most suitable for determent hemolysis forms. If the culture medium base is to be used without blood, the pH should, however, be adjusted to 7.3 ± 0.2 since most bacterial colonies appear somewhat earlier and grow better in a slightly alkaline medium. This medium inhibits gram-positive bacteria especially bacilli and fecal Streptococci with α- hemolytic activity, however, Neisseria sp. showed none of the hemolytic activity with good growth pattern of culture after incubation period of 48 hours.