Description
A differential and slightly selective agar, based on the formulation of Leifson, which is highly heat sensitive.
It is used in a pour plate technique when performing coliform counts on milk and cream but is surface inoculated when utilised in the isolation of enteric pathogens from clinical samples.
Lactose fermenting organisms appear as pink to red colonies due to the absorption of the neutral red indicator. Precipitate surrounding the colony is due to bile (desoxycholic acid), following dissociation of neutral red from sodium desoxycholate which had previously been combined in acid pH. Sodium desoxycholate and sodium citrate inhibit the growth of Gram positive organisms and non-lactose fermenting non-enteric Gram negative organisms.
