Remel™ HE Agar

Selectively isolate and differentiate gram-negative enteric pathogens using Thermo Scientific™ Remel™ Hektoen Enteric (HE) Agar (Dehydrated). The HE Agar slightly modified from the original formulation and has lower bile salt concentrations and the absence of sodium desoxycholate. King and Metzger developed HE Agar to simultaneously grow Salmonella and Shigella as well as inhibit normal intestinal flora¹.

HE Agar is a selective and differential agar primarily used to recover Salmonella and Shigella from patient specimens. In the medium the amount of carbohydrate and peptone was increased to counteract the inhibitory effects of bile salts and indicators.

• Selective medium - Growth of gram-positive organisms is inhibited by bile salts
• Differential medium - Addition of sucrose, lactose and salicin helps in differentiating pathogens based on the color of colonies and the medium surrounding them.
• Easy to interpret –
  • Shigella: green colonies
  • Salmonella: green colonies with a black precipitate in the center

Meat peptone supplies essential nutrients for bacterial growth. Sucrose, lactose and salicin are added to help differentiate pathogens. If hydrogen sulphide is produced from sodium thiosulphate it reacts with ferric ammonium citrate to form a black precipitate in the center of the colony. Acid fuchsin and bromthymol blue are indicators with low toxicity and bile salts inhibit the growth of gram-positive organisms.