Tryptose Blood Agar Base, 500 g

Tryptose Blood Agar Base is a tryptose based medium that can be used for the cultivation of fastidious organisms (1, 2), 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 (3) and APHA (4). Tryptose Blood Agar Base can be used as a generalpurpose 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 (6). Tryptose and beef extract provide nitrogenous and carbonaceous compounds, sulphur, vitamin B complex and trace elements essential for bacterial metabolism. Blood provides additional nutrients and serves as a base to study haemolytic reactions. This medium not only keeps the blood cells in a good state but also help in forming distinct haemolysis. Perform biochemical test for further identification (5). Storage and Shelf-life: Store below 30°C in tightly closed container and the prepared medium at 2-8°C. Use before expiry date on the label. References: 1. Casman E. P., 1942, J. Bacteriol., 43:33. 2. Casman E. P., 1947, Am. J. Clin. Pathol., 17: 281. 3. FDA Bacteriological Analytical Manual, 8th Ed., 1995, AOAC International, Gaithersburg, Md. 4. American Public Health Association, 1970, Diagnostic Procedures and Reagents, 5th Ed., APHA Inc., New York. 5. MacFaddin J. F., 1985, Media for Isolation-Cultivation-Identification-Maintenance of Medical Bacteria, Vol. 1, Williams and Wilkins, Baltimore. 6. Koneman E. W., Allen S. D., Janda W. M., Schreckenberger P. C., Winn W. C. Jr., 1992, Colour Atlas and Textbook of Diagnostic Microbiology, 4th Ed., J. B. Lippinccott Company.