BROMOTHYMOL LACTOSE BLUE AGAR

Reactions with lactose are of great practical importance for the primary isolation of Enterobacteria from clinical specimens. The specimens e.g. faeces is usually plated on a lactose-containing medium on which lactose fermenters and lactose non fermenters form coloured and pale colonies respectively due to the dye incorporated. This procedure makes an immediate presumptive distinction between colonies of the true intestinal pathogens possible. Salmonella and Shigella, do not ferment lactose while the common intestinal commensals, Escherichia and Klebsiella, which do ferment lactose. Bromothymol Lactose Blue Agar is used for differentiating lactose fermenting and non-fermenting bacteria belonging to the family Enterobacteriaceae.

It is a selective medium used for the isolation of Gram-negative bacteria from urine & faeces