Tellurite Egg Yolk Emulsion

Add aseptically 5 mL to melted bottles of Baird-Parker base medium (100 mL) cooled to 50 °C, before pouring into Petri dishes when cooled to room temperature.

Once solidified on a flat surface, spread the plates by streaking methodology or by spiral method. Incubate the plates right side up aerobically at 35-37 °C for 24-48 hours.

(Incubation times longer than those mentioned above or different incubation temperatures may be required depending on the sample, on the specifications, etc.)

After incubation, enumerate all the black-brownish colonies that have appeared on the surface of the agar with a double halo: an inner white halo (lipase action) and an outer halo of clear medium (lecithinase activity).

Each laboratory must evaluate the results according to their specifications.

Presumptive isolation of S. aureus must be confirmed by further microbiological and biochemical tests.

Calculate total microbial count per mL of sample by multiplying the average number of colonies per plate by the inverse dilution factor if a diluted sample was streaked. Report results as colony forming units (CFU) per mL or g along with incubation time and temperature.

Precautions

Do not reuse. For professional use only.

Do not use the product if it shows evidence of microbial contamination, discoloration, drying, cracking or other signs of deterioration.

Physical/chemical control

Microbiological control

Add 5 mL of product to 100 mL of Baird Parker Agar Base.

Inoculate: practical range 100 ± 20 CFU, min. 50 CFU (productivity) / 10⁴-10⁶ (selectivity).

Analytical methodology according to ISO 11133:2014/Amd 1:2018; A2:2020.

Aerobiosis. Incubation at 37 ± 1 °C, reading after 24-48 ± 2 h.

Sterility control

Inoculate 10 mL of product in 100 mL THIO USP / TSB. Incubate and verify in TSA.

Incubation 7 days at 30-35 °C: NO GROWTH.

• BAIRD-PARKER, A.C. (1962) An improved diagnostic and selective medium for isolating coagulase-positive staphylococci. J. Appl. Bact. 25:12.
• EUROPEAN PHARMACOPOEIA (2007) 5th ed. Suppl. 5.6 § 2.6.13 Microbiological examination of non-sterile products. EDQM. Council of Europe. Strasbourg.
• FIL-IDF 60:2001 Standard. Lait et produits à base de lait - Detection des staphylocoques à coagulase positive - Technique du nombre le plus probable. Brussels.
• ISO 11133:2014/Amd 1:2018. Microbiology of food, animal feed and water. Preparation, production, storage and performance testing of culture media.
• USP 31 - NF 26 (2008) <61> Microbial Limit Tests. US Pharmacopoeial Conv. Inc. Rockville. MD. USA.
• ZANGERL, P. & H. ASPERGER (2003) Media used in the detection and enumeration of Staphylococcus aureus. In Handbook.