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Hektoen Enteric Agar | Selective Medium for Salmonella & Shigella | AS‑1248
$45.00 AUD
AuSaMicS Life Science • Enteric Pathogen Media
Hektoen Enteric Agar
Selective & Differential Medium for Salmonella and Shigella
Hektoen Enteric Agar (HEA) is a selective and differential plating medium used for the isolation of Salmonella and Shigella from stool, enteric pathological specimens, food, and related samples. Its balanced formulation combines bile-salt selectivity, multiple fermentable carbohydrates, and an H2S indicator system to help distinguish enteric pathogens from coliform background flora.
AS-1248 pH 7.5 ± 0.2 ✓ Australian Stock 🧫 Salmonella / Shigella ⚫ H₂S Detection
Selective agent: bile salts mixture Differentiation: lactose + sucrose + salicin Documents: COA + SDS + TDS
🏆 HEA Differentiation at a Glance
Coliform fermenters — salmon/orange colonies
Shigella — green to blue-green colonies
Salmonella — blue-green with black centres
Bile salts — suppress Gram-positive flora
Confirmation required — biochemical/serological follow-up
Key Readout Logic
Carbohydrate fermenter → salmon/orange
Non-fermenter → green / blue-green
H₂S producer → black precipitate
Non-fermenter → green / blue-green
H₂S producer → black precipitate
⚠️ Important: HE Agar is a Presumptive Isolation Medium — Not a Final Identification Test
What HEA does well
Provides strong primary visual differentiation between lactose/sucrose/salicin fermenters, non-fermenters, and H2S producers, helping labs rapidly screen suspect Salmonella and Shigella colonies. :contentReference[oaicite:1]{index=1}
Provides strong primary visual differentiation between lactose/sucrose/salicin fermenters, non-fermenters, and H2S producers, helping labs rapidly screen suspect Salmonella and Shigella colonies. :contentReference[oaicite:1]{index=1}
What HEA does not replace
Suspect colonies still require confirmation by biochemical, serological, or molecular methods because colony appearance alone is not definitive. :contentReference[oaicite:2]{index=2}
Suspect colonies still require confirmation by biochemical, serological, or molecular methods because colony appearance alone is not definitive. :contentReference[oaicite:2]{index=2}
🔬 Technical Overview & Principle
Hektoen Enteric Agar was developed to improve the recovery of Shigella and Salmonella from enteric specimens while still inhibiting much of the normal intestinal flora. Compared with harsher enteric media, its formulation uses higher peptone and carbohydrate levels and a balanced indicator system so that Shigella remains recoverable while coliforms and other fermenters are more clearly differentiated. :contentReference[oaicite:3]{index=3}
Carbohydrate differentiation
Lactose, sucrose, and salicin allow carbohydrate-fermenting enterics to produce salmon to orange colonies, making non-fermenting pathogens easier to recognise. :contentReference[oaicite:4]{index=4}
Lactose, sucrose, and salicin allow carbohydrate-fermenting enterics to produce salmon to orange colonies, making non-fermenting pathogens easier to recognise. :contentReference[oaicite:4]{index=4}
H₂S detection system
Sodium thiosulphate and ferric ammonium citrate detect hydrogen sulphide production, producing black-centred colonies in typical H₂S-positive organisms such as many Salmonella. :contentReference[oaicite:5]{index=5}
Sodium thiosulphate and ferric ammonium citrate detect hydrogen sulphide production, producing black-centred colonies in typical H₂S-positive organisms such as many Salmonella. :contentReference[oaicite:5]{index=5}
Lactose / sucrose / salicin fermenter
↓
Acid production + indicators shift
→ Salmon / orange colonies
Non-fermenter
↓
Minimal acid production
→ Green / blue-green colonies
H₂S producer
↓
Thiosulphate reduction + ferric salt reaction
→ Black centre / black precipitate
↓
Acid production + indicators shift
→ Salmon / orange colonies
Non-fermenter
↓
Minimal acid production
→ Green / blue-green colonies
H₂S producer
↓
Thiosulphate reduction + ferric salt reaction
→ Black centre / black precipitate
Typical interpretation: Salmonella usually appears as blue-green colonies with black centres, Shigella as green to blue-green colonies without blackening, and coliform fermenters as salmon/orange colonies. :contentReference[oaicite:6]{index=6}
🧪 Detailed Ingredients Table
🧫 Typical Interpretation Workflow
1
Primary plating
Inoculate stool, enteric pathological specimen, or relevant food-enrichment sample onto HEA using standard laboratory technique. HEA is commonly used as a primary screening plate in enteric pathogen workflows. :contentReference[oaicite:20]{index=20}
Inoculate stool, enteric pathological specimen, or relevant food-enrichment sample onto HEA using standard laboratory technique. HEA is commonly used as a primary screening plate in enteric pathogen workflows. :contentReference[oaicite:20]{index=20}
2
Incubate and inspect colony colour
Carbohydrate fermenters generally appear salmon to orange, while non-fermenters remain green to blue-green. This gives a strong first-pass separation of coliform background flora from possible enteric pathogens. :contentReference[oaicite:21]{index=21}
Carbohydrate fermenters generally appear salmon to orange, while non-fermenters remain green to blue-green. This gives a strong first-pass separation of coliform background flora from possible enteric pathogens. :contentReference[oaicite:21]{index=21}
3
Assess H₂S reaction
Black-centred colonies suggest H₂S production and increase suspicion for Salmonella in the correct workflow context. Green colonies without blackening may be consistent with Shigella. :contentReference[oaicite:22]{index=22}
Black-centred colonies suggest H₂S production and increase suspicion for Salmonella in the correct workflow context. Green colonies without blackening may be consistent with Shigella. :contentReference[oaicite:22]{index=22}
4
Confirm suspect colonies
Any presumptive Salmonella or Shigella isolate should be subcultured and confirmed by appropriate biochemical and/or serological testing. :contentReference[oaicite:23]{index=23}
Any presumptive Salmonella or Shigella isolate should be subcultured and confirmed by appropriate biochemical and/or serological testing. :contentReference[oaicite:23]{index=23}
📊 Comparative Enteric Pathogen Media
📌 Quick Specifications
Product: Hektoen Enteric Agar
Cat. No.: AS-1248
Format: Dehydrated culture medium
Target organisms: Salmonella, Shigella
Selectivity: Bile salts based
Differentiation: Carbohydrate fermentation + H₂S
Typical applications: Stool, enteric pathology, food microbiology
Storage: 10–25°C, dry, tightly closed, protected from moisture and light
⭐ Why Labs Use HEA
✓Reliable presumptive differentiation of key enteric pathogens
✓Excellent contrast between fermenters and non-fermenters
✓Built-in H₂S reaction aids Salmonella screening
✓Suitable for clinical, food, and QC microbiology workflows
✓Trusted classical medium often paired with XLD or other selective plates
🎨 Typical Colony Guide
Salmon / orange: lactose/sucrose/salicin fermenters, often coliform background flora. :contentReference[oaicite:30]{index=30}
Green / blue-green: non-fermenters such as typical Shigella. :contentReference[oaicite:31]{index=31}
Blue-green with black centre: typical presumptive Salmonella reaction due to H₂S production. :contentReference[oaicite:32]{index=32}
🔗 Related AuSaMicS Products
XLD Agar
Complementary selective medium often used in parallel for enteric pathogens
SS Agar
Classical alternative for Salmonella/Shigella isolation workflows
Buffered Peptone Water / enrichment media
Useful upstream enrichment options for food microbiology testing
Trusted Enteric Media for Clearer Colony Differentiation
AuSaMicS supplies high-quality microbiological media designed for reliable performance in routine clinical, food, and industrial microbiology. Contact us for technical support, bulk supply, or method-aligned documentation.
For laboratory, research, and industrial use only. Not for food, feed, household, cosmetic, therapeutic, or personal use.
AuSaMicS Pty Ltd • ABN 56 676 640 467 • 31 Longview CT, Thomastown, VIC 3074, Australia
www.ausamics.com.au • support@ausamics.com • +61 412 520 598