Brilliant Green Agar with 1.2% Agar, 500 g

Salmonella species cause many types of infections, from mild self-limiting gastroenteritis to life threatening typhoid fever. The most common form of Salmonella disease is self-limiting gastroenteritis with fever lasting less than 2 days and diarrhoea lasting less than 7 days (7). Brilliant Green Agar as a primary plating medium for isolation of Salmonella species was first described by Kristensen et al (1) and further modified by Kauffmann (2) and recommended by APHA (3, 4) FDA (5) and USP (6). These media contain brilliant green which inhibits growth of majority of gram-negative and gram-positive bacteria. Salmonella Typhi, Shigella species, Escherichia coli , Proteus species, Pseudomonas species Staphylococcus aureus are mostly inhibited. Clinical specimens can be directly plated on this medium. However, being highly selective, it is recommended that this medium should be used alongwith a less inhibitory medium to increase the chances of recovery. Often cultures enriched in Selenite (M025A) or Tetrathionate Broth (M032) are plated on Brilliant Green Agar as well as Bismuth Sulphite Agar (M027), SS Agar (M108) and MacConkey Agar (M081). Phenol red serves as an acid base indicator giving yellow colour to lactose and or sucrose fermenting bacteria. Lactose non-fermenting bacteria develop white to pinkish red colonies within 18 - 24 hours of incubation. Salmonella Typhi and Shigella species may not grow on this medium, moreover Proteus, Pseudomonas and Citrobacter species may mimic enteric pathogens by producing small red colonies. 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.Kristensen M., Lester V. and Jurgens A., 1925, Brit.J.Exp.Pathol.,6:291. 2.Kauffman F., 1935, Seit F. Hyg., 177:26. 3.Vanderzant C. and Splittstoesser D. (Eds.), 1992, Compendium of Methods for Microbiological Examination of Foods, 3rd ed. APHA, Washington D.C. 4.Marshall R. (Ed.), 1992, Standard Methods for the Microbiological Examination of Dairy Products, 16th ed., APHA, Washington, D.C. 5.Bacteriological Analytical Manual, 1978, 5th ed, AOAC, Washington D.C. 6.The United States Pharmacopoeia, 1985, 21st Rev., USP Convention, Rockville MD. 7.Murray P.R., Baron J.H., Pfaller M.A., Jorgensen J.H., and Yolken R.H., (Ed.), 2003, Manual of Clinical Microbiology, 8th Ed., American Society for Microbiology, Washington, D.C.