Glucose Cysteine Agar Base w/ Thiamine with added blood or haemoglobin or hemin (CHAB) is used for cultivation and enumeration of Francisella tularensis (Pasteurella tularensis). Francisella tularensis, a gram-negative aerobic bacillus, is the etiological agent of tularemia, which is primarily a disease of wild animals that is perpetuated in nature by ectoparasites, contaminated environment, cannibalism and acute or chronic carriers. Biting and blood sucking insects serve as vectors 1. Francisella (formerly known as Pasteurella) cannot be cultured on ordinary medium but require a complex medium containing blood or tissue extracts, thiamine and cysteine 2, 3. Glucose Cysteine Agar Base w/ Thiamine when supplemented with blood / haemoglobin is recommended for cultivation and enumeration of F. tularensis (Pasteurella tularensis) 4. Peptone and soy peptone provide essential growth nutrients. Dextrose serves as an easily metabolisable carbohydrate source while sodium chloride maintains the osmotic balance. Thiamine and cysteine hydrochloride serves as growth factor promoters required for culturing Pasteurella. Minute droplet like colonies develops in 48 hours.
1. 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.
2. Collee J. G., Marmion B. P., Fraser A. G., and Simmons A., (Eds.), Mackie and McCartney Practical Medical Microbiology, 1996, 14th Edition, Churchill Livingstone, New York.
3. Manual of Diagnostic Tests and Vaccine for Terrestrial Animals, 2004, 5th Edi, OIE World Organization for Animal Health.