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Selectively isolate and enumerate Bacillus cereus from food samples with Thermo Scientific™ Oxoid™ Bacillus cereus Selective Agar Base (Dehydrated). Bacillus cereus Selective Agar Base meets the requirements for a medium that is sufficiently selective to be able to detect small numbers of Bacillus cereus cells and spores in the presence of large numbers of other food contaminants. The medium is also sufficiently diagnostic that colonies of Bacillus cereus are readily identified and confirmed by microscopic examination.

Bacillus cereus Selective Agar Base, Oxoid Composition

Bacillus cereus Selective Agar Base, Oxoid Preparation:
Suspend 20.5g in 475ml of distilled water and bring gently to the boil to dissolve completely. Sterilise by autoclaving at 121°C for 15 minutes. Cool to 50°C and aseptically add the contents of one vial of Polymyxin B Supplement (SR0099) reconstituted as directed, then add 25ml of sterile Egg Yolk Emulsion (SR0047). Mix well and pour into sterile Petri dishes.

Storage conditions and Shelf life
Store the dehydrated medium at 10-30°C and Polymixin B Supplement at 2-8°C. Use before the expiry date on the label.
The prepared medium may be stored at 2-8°C.

Precautions
On this medium Bacillus cereus is indistinguishable from Bacillus thuringiensis.
Identify Bacillus cereus by colony form, colour, egg yolk hydrolysis and confirm with cell and spore morphology.
Occasional strains of Bacillus cereus show weak or negative egg yolk reactions.

Baird Parker Agar Base, Oxoid is suitable for the isolation and enumeration of Staphylococcus aureus, with high selectivity and sensitivity. It contains carefully balanced selective inhibitory agents, glycine, lithium, and tellurite, to suppress the growth of most of the bacteria present in foods without inhibiting coagulase-positive staphylococci. The presence of egg yolk emulsion and sodium pyruvate aid the recovery of damaged cells for presumptive identification of Staphylococcus aureus in food specimens.

Baird Parker Agar Base, Oxoid Preparation:

Suspend 6.3g of Baird-Parker Agar Base (RPF) in 90ml of distilled water. Bring to the boil to dissolve completely. Sterilise by autoclaving at 121ºC for 15 minutes. Cool to 48ºC and add 1 vial of RPF Supplement (SR0122A), reconstituted as directed. Mix well and pour plates.

Storage Conditions and Shelf Life
Store the dehydrated medium at 10-30°C and RPF Supplement below 0°C. Use before the expiry date on the label.
Prepared plates of the medium are best used freshly prepared.

Precautions
Regard all suspicious colonies as Staphylococcus aureus regardless of negative reactions in the medium and carry out further tests.
Colonies of some contaminating organisms growing in close proximity to the coagulase positive colonies may partially digest the coagulase halo reaction.

Isolate, enumerate, and identify coagulase positive Staphylococcus aureus in food samples with selective Thermo Scientific™ Oxoid™ Baird Parker Agar (ISO) Base (Dehydrated) while adhering to ISO 6888-1:1999.

Baird Parker Agar (ISO) Base, Oxoid Composition

Baird Parker Agar (ISO) Base, Oxoid Preparation:
Suspend 63g of Baird-Parker Agar (ISO) Base in 1,000ml of distilled water. Boil to dissolve the medium and sterilise by autoclaving at 121°C for 15 minutes. Cool to 47°C and aseptically add 50ml of Egg Yolk Tellurite Emulsion (SR0054). Mix well and pour into sterile Petri dishes.

Storage conditions and Shelf life
Store the dehydrated medium at 10-30°C and use before the expiry date on the label.
The prepared medium is best used freshly prepared, but may be suitable for longer storage following in-house validation.

Precautions
Atypical colonies have the same size as typical colonies but can be shining black with or without a narrow white edge; the clear zone or opacity halo can also be absent or barely visible. Grey colonies, free of clear zone, can also be regarded as atypical.
Regard all typical and atypical colonies as coagulase-positive staphylococci irrespective of negative reactions on the medium and carry out further tests.
Colonies of some contaminating organisms growing in close proximity to the coagulase positive colonies may partially digest the coagulase halo reaction.

• The Oxoid Baird-Parker RPF Agar Base is a selective medium for the isolation and enumeration of coagulase positive staphylococci from food.
• For use with RPF supplement, Part No. SR0122A
• Do not use Egg Yolk Tellurite Emulsion.

Baird-Parker Agar Base (RPF), Oxoid Composition

Baird-Parker Agar Base (RPF), Oxoid Preparation:
Suspend 6.3g of Baird-Parker Agar Base (RPF) in 90ml of distilled water. Bring to the boil to dissolve completely. Sterilise by autoclaving at 121ºC for 15 minutes. Cool to 48ºC and add 1 vial of SR0122A, reconstituted as directed. Mix well and pour plates.

Storage conditions and Shelf life
Store the dehydrated medium at 10-30°C and RPF Supplement below 0°C. Use before the expiry date on the label.
Prepared plates of medium are best used freshly prepared.

Precautions
Colonies of some contaminating organisms growing in close proximity to the coagulase positive colonies may partially digest the coagulase halo reaction.

Oxoid Basic Fuchsin Indicator is a dye for use with Endo Agar Base, Part No. CM0479B and m Endo (LES) Agar Base, Part No. MM0551B.

Basic Fuchsin Preparation:

BR0050 should be dissolved to create a 10% w/v solution using 95% ethyl alcohol.

For each litre of culture medium use the amount described in the product reconstitution details.  This should be in a 10% w/v solution of the dye dissolved in 50:50 ethanol/distilled water.  E.g. For CM0479 add 6ml of a 10% w/v Basic Fuchsin solution per litre of medium.

The magenta dyes are closely related to known carcinogenic substances; therefore basic fuchsin should be handled with care, avoiding inhaling the powder or staining the skin with dye.