BacterPlate™ Baird Parker Agar (BPA)

Ready-to-use medium on 90mm plates for counting coagulase-positive Staphylococci.
Code: 05003
Packaging: 10 plates/ box or as per customer request.
Storage Conditions: 2–8°C.
Transportation: Ambient temperature.
Shelf Life: 04 months from the date of manufacture.

INTENDED USE

BacterPlate™ Baird Parker Agar (BPA) e is a selective medium for the detection and enumeration of coagulase-positive staphylococci (Staphylococcus aureus and other species) in animal origin biological samples, pharmaceutical products, cosmetics, foods and water.
The typical composition is that defined in the food chain microbiology directives NF EN ISO 6888-1 and NF EN ISO 6888-3.
The packaging with semi-permeable Cellophane film helps balance the humidity of the environment during storage.

PRINCIPLES

The growth of staphylococci is favored by sodium pyruvate and glycine.
Accompanying microflora is inhibited by lithium chloride and potassium tellurite (added extemporaneously), as well as a high concentration of glycine.
The addition of sulfamethazine (optional) after autoclaving inhibits most Proteus and thus limits the invasion of the medium by this species.
Enrichment with egg yolk aids in identification by showing the action of lecithinase.
Staphylococcus aureus presents black or grey colonies (due to the reduction of tellurite to telluride), surrounded by clearing zones in the cloudy egg yolk medium.
In principle, other microorganisms are inhibited.
However, it is possible to observe brown or greenish micrococci, white yeast colonies or brown Bacillus or Proteus.

1. Enumeration of coagulase positive staphylococci (Food microbiology, NF EN ISO 6888-1)

To the surface of plate BacterPlate™ Baird Parker Agar (BPA) brought to room temperature, transfer 0.1 mL of the sample to analyze and its serial tenfold dilutions.
Spread the inoculum on the surface of the agar with a sterile triangle.
Incubate between 34°C and 38°C at 24 ± 2 hours and 48 ± 4 hours.

2. Detection of Staphylococcus aureus (Cosmetics, NF EN ISO 22718)

To the surface of plate BacterPlate™ Baird Parker Agar (BPA) brought to room temperature, inoculate by streaking a loop of enrichment broth
Incubate at 30 – 35°C for 24 to 48 hours.

RESULTS

Staphylococcus aureus is characterized by the formation of black or grey colonies (reduction of tellurite to telluride), 1.5 mm to 2.5 mm in diameter after 48 hours of incubation, surrounded by a halo of clearing which can be partially opaque.
Non-characteristic colonies are black or grey with or without a clear zone.
Presumptive Staphylococcus aureus must be confirmed by the coagulase test.

BacterLab ensures the quality of each product batch by testing with ATCC reference strains.

Reference Strains and Incubation Conditions	Standard (P_R)
Incubation conditions after 24 – 48 hours, at 35 – 37°C, with inoculum ≤ 10² CFU/ mL
S. aureus ATCC 25923	≥ 50 %
Incubation conditions after 24 – 48 hours, at 35 – 37°C, with inoculum ≤ 10³ – 10⁴ CFU/ mL
S. epidermidis ATCC 12228	Weak growth
E. coli ATCC 35218	Inhibited, no growth

For 1 liter of medium

Tryptone	10,0 g
Meat extract	5,0 g
Yeast extract	1,0 g
Sodium pyruvate	10,0 g
Glycine	12,0 g
Lithium chloride	5,0 g
Egg yolk emulsion	50,0 mL
Potassium tellurite at 3,5%	3,0 g
Sulfamethazine (if necessary)	50,0 mg
Agar	15,0 g