Liofilchem™ Egg Yolk Tellurite Emulsion

ISO 6888-Compliant Supplement for the Detection of Coagulase-Positive Staphylococcus aureus

Liofilchem® Egg Yolk Tellurite Emulsion is a sterile, stabilized supplement used in combination with Baird Parker Agar Base for the isolation, enumeration, and presumptive identification of coagulase-positive Staphylococcus aureus in food samples, according to ISO 6888-1 and ISO 6888-3 standards.

The supplement contains chicken egg yolk in saline (0.9% NaCl) and potassium tellurite (2 g/L), which enables simultaneous detection of lecithinase activity and tellurite reduction. When added to Baird Parker Agar, the complete medium supports selective growth of S. aureus, which is visualized as black or grey colonies surrounded by clear halos due to lecithinase activity.

Key Features & Benefits

• ISO 6888-Compliant – Supports international protocols for food microbiology
• Ready-to-Use Emulsion – Pre-sterilized and stabilized for consistent results
• Dual Indicator Function – Detects lecithinase activity (clear halo) and tellurite reduction (black colonies)
• Enhanced Selectivity – Inhibits growth of competing flora like E. coli
• Easy Integration – Simply add 50 mL of emulsion to 1 L of autoclaved Baird Parker Agar Base
• Versatile Pack Sizes – Available in 4 × 50 mL and 6 × 100 mL formats

Intended Use

For the isolation and enumeration of Staphylococcus aureus and other coagulase-positive staphylococci from food and animal feed samples, when used with Baird Parker Agar Base (Liofilchem Ref. 610004 or 620004).

Technical Specifications

Principle of the Method

• Lecithinase activity of S. aureus degrades egg yolk, forming clear halos around colonies.
• Potassium tellurite is reduced by S. aureus, producing black or grey colonies.
• The emulsion enhances the selectivity and differentiation capacity of the Baird Parker medium.

Microbiological Performance (48 hrs at 37 °C)

Instructions for Use

1. Autoclave 1 L of Baird Parker Agar Base and cool to 45–50 °C.
2. Aseptically add 50 mL of Egg Yolk Tellurite Emulsion. Mix thoroughly.
3. Pour into sterile Petri dishes.
4. Inoculate test sample and incubate at 37 ± 1°C for 24–48 hours.
5. Interpret Results based on colony morphology and halo formation.

Warnings & Precautions

• For professional use only
• Not classified as hazardous, but consult the SDS before use
• Do not use if product shows contamination, discoloration, or expiration
• Follow biosafety and disposal regulations for microbial media

Ordering Information

Conclusion

Liofilchem® Egg Yolk Tellurite Emulsion is a critical supplement for selective and differential detection of coagulase-positive Staphylococcus aureus on Baird Parker Agar. Compliant with ISO 6888 standards, this supplement enables accurate and reliable enumeration and isolation of S. aureus in food microbiology testing. Its ready-to-use formulation, high-quality consistency, and compatibility with standard lab procedures make it an essential component in food safety and public health microbiology laboratories.