TRYPTOSE BLOOD AGAR BASE

Tryptose Blood Agar Base is a tryptose based medium that can be used for the cultivation of fastidious organisms, on supplementation with blood. This medium is devoid of dextrose and therefore useful in determining the haemolytic reactions. Tryptose Blood Agar Base is recommended by FDA and APHA. Tryptose Blood Agar Base can be used as a general-purpose medium without supplementation of blood. These media can be used to determine the heamolytic reactions of fastidious organisms.
The four different types of haemolysis observed are as follows:
a) Alpha haemolysis: partial lysis of the erythrocytes surrounding colony, causing a grey green or brownish discolouration in the media.
b) Beta haemolysis: complete lysis of the red blood cells surrounding a colony, causing a clearing of blood from the medium.
c)Gamma haemolysis: no haemolysis and consequently, no colour change of the medium surrounding a colony. Organisms showing no haemolysis are generally termed non-hemolytic rather than gamma haemolytic.
d) Alpha-prime or wide zone alpha: a small zone of intact erythrocytes immediately adjacent to the colony, with a zone of complete red cell haemolysis surrounding the zone of intact erythrocytes. This type of haemolysis may be confused with beta haemolysis.

For enrichment and isolation of various fastidious microorganisms and determining the haemolytic reactions