Hektoen Enteric Agar Medium (250g) - HEA Medium for selective isolation of intestinal bacteria

Hektoen Enteric Agar (HEA / HEK Agar)

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Hektoen Enteric Agar (HEA / HEK Agar) is a selective and differential solid medium designed for the isolation and differentiation of enteric pathogens, particularly Salmonella and Shigella species, from fecal, food, water, and environmental samples.

The high concentration of bile salts and sodium deoxycholate effectively inhibits Gram-positive organisms and many non-enteric bacteria. Lactose, sucrose, and salicin, combined with pH indicators (bromothymol blue and acid fuchsin), allow differentiation based on carbohydrate fermentation. Sodium thiosulfate and ferric ammonium citrate enable detection of hydrogen sulfide (H₂S) production.

⚠ For laboratory research and quality control use only. Not for clinical diagnostic or therapeutic use.

🔬 Intended Use

  • Selective isolation of Salmonella spp.

  • Isolation and differentiation of Shigella spp.

  • Food and water microbiological analysis

  • Environmental monitoring

  • Pharmaceutical microbiology testing

📦 Product Specifications

  • Product Name: Hektoen Enteric Agar

  • Abbreviations: HEA / HEK Agar

  • Physical Form: Dehydrated powder

  • Package Size: 250 g / bottle

  • Storage Condition: Room temperature, dry place

  • Shelf Life: 3 years

🧬 Medium Composition (per liter)

  • Proteose Peptone …………………………………. 12.0 g
  • Beef Extract ………………………………………… 3.0 g
  • Sucrose ……………………………………………….. 12.0 g
  • Lactose ………………………………………………… 12.0 g
  • Salicin ………………………………………………….. 2.0 g
  • Bile Salts ……………………………………………… 20.0 g
  • Sodium Chloride …………………………………. 5.0 g
  • Sodium Thiosulfate …………………………… 6.8 g
  • Ferric Ammonium Citrate ……………….. 0.8 g
  • Sodium Deoxycholate ……………………….. 2.0 g
  • Acid Fuchsin ………………………………………. 0.1 g
  • Bromothymol Blue …………………………… 0.064 g
  • Agar ……………………………………………………. 18.0 g
  • Final pH: 7.5 ± 0.2 (at 25 °C)

⚗️ Preparation Instructions

  1. Suspend 93.8 g of dehydrated medium in 1,000 ml of distilled or deionized water
  2. Heat with frequent agitation and boil for 1 minute until completely dissolved
  3. Do NOT autoclave
  4. Cool slightly and pour into sterile Petri dishes
  5. Allow agar to solidify and use as required

🧫 Typical Colony Appearance

  • Salmonella spp.: Blue-green colonies with black centers (H₂S positive)
  • Shigella spp.: Green to blue-green colonies without black centers
  • Lactose/Sucrose fermenters: Orange to salmon-colored colonies

🧫 Storage & Stability

  • Store dehydrated medium at room temperature, protected from moisture and light
  • Prepared plates should be used as soon as possible
  • Do not use if clumping, discoloration, or contamination is observed

⚠️ Limitations & Precautions

  • Autoclaving will destroy selective and differential properties
  • Overheating may degrade dyes and carbohydrates
  • Handle biological samples following appropriate biosafety guidelines

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