CHRISTENSEN CITRATE AGAR

Christensen Citrate Agar is a modification of Christensen Iron Agar, which has the same formulation except the additional sodium thiosulphate and ferric ammonium citrate as described by Edwards and Ewing. Christensen reported that all members of genera Escherichia, Enterobacter, Citrobacter and Salmonella were capable of utilizing citrate as a source of energy while Shigella species failed to utilize citrate. Edward and Ewing recommended the use of Triple Sugar Iron Agar for the determination of hydrogen sulphide production and Christensen Citrate Agar for citrate utilization. Organisms that metabolize citrate as a sole source of carbon cleave citrate to oxaloacetate and acetate via the citritase enzyme. Another enzyme, oxaloacetate decarboxylase, then converts oxaloacetate to pyruvate and CO2. Further, this CO2 combines with sodium and water to form sodium carbonate, an alkaline compound. As a result, the pH of medium rises and the indicator, phenol red changes from orange red to cerise. Presence of the cerise colour indicates a positive finding for citrate utilization.

for di?erentiation of enteric pathogens and coliforms on the basis of citrate utilization

#Klebsiella aerogenes | Escherichia coli | Klebsiella pneumoniae | Salmonella Enteritidis | Salmonella Typhimurium | Shigella flexneri | Shigella sonnei

Clinical Diagnostics | Industrial & Lab Purposes | Water

100 gm | 500 gm