Hektoen Enteric Agar

· Purpose: To isolate and differentiate Salmonella and Shigella species from other gram-negative enteric organisms.

· Contents of HE Agar: Dyes and bile salts.

· Uses of the contents in HE Agar: Inhibits growth of gram-positives and high concentrations of three sugars: lactose, sucrose and the plant glycoside salicin. Sugars that produce acid, changes the colour of the dyes. Acid-producers form orange or pink colonies and non-acid producers form greenish colonies.

· Examples of acid producers and non-acid producers:



















E. coli on Hektoen enteric agar
Bright yellow-orange colonies are formed

Salmonella enteric on Hektoen enteric agar

Greenish colonies are formed