DOUBLE SUGAR AGAR, RUSSELL

Gram-negative bacilli belonging to Enterobacteriaceae are the most frequently encountered bacterial isolates recovered from clinical specimens. Definitive identification of the members of Enterobacteriaceae requires a battery of biochemical tests. Double Sugar Agar, Russell is used for the differentiation of gram-negative enteric bacilli on the basis of their ability to ferment dextrose and lactose with or without gas formation. This medium was originally formulated by Russell using litmus indicator. It was later modified by Nichols and Nichols and Wood by replacing the litmus indicator with phenol red. This medium is used for differentiating gram-negative enteric bacilli especially the colon-typhoid-salmonellae-dysentery groups based on the fermentation of the double sugars incorporated namely, dextrose and lactose.

for di?erentiation of gram-negative enteric bacilli based on their ability to ferment dextrose and lactose, with or without gas formation