BAIRD-PARKER AGAR (BASE)

General description

GranuCult^® Baird-Parker agar (base) is used for the isolation and enumeration of Staphylococcus aureus. This medium contains lithium chloride and tellurite to inhibit the growth of accompanying microbial flora, whereas pyruvate and glycine selectively stimulate the growth of staphylococci. Agar is the solidifying agent. The egg-yolk content makes the medium opaque. Staphylococcus colonies show two characteristic features when grown in this medium: (a) characteristic zones and rings are formed as a result of lipolysis and proteolysis, and (b) reduction of tellurite to tellurium produces a black coloration. The egg-yolk reaction and tellurite reduction usually occur together with a positive coagulase reaction and thus can serve as an index for the latter. According to EN ISO 6888-1, the addition of sulfamethazine is advised to suppress the growth and swarming of Proteus sp., if these are suspected in the test sample.

Application

GranuCult^® Baird-Parker agar (base) is used for the isolation, presumptive identification, and enumeration of Staphylococcus aureus from food and animal feed as well as from other materials.

Linkage

Replaces: 1.05406.5007

Analysis Note

Appearance (clearness): clear to turbid
Appearance (color): yellowish-brown
pH-value (25 °C): 6.6 - 7.0
Solidification behaviour (2 hrs., 45 °C): liquid
Growth promotion test in accordance with the current version of DIN EN ISO 11133.
Inoculum on reference medium (Staphylococcus aureus ATCC 6538 (WDCM 00032)):
Inoculum on reference medium (Staphylococcus aureus ATCC 25923 (WDCM 00034)):
Colony count (Staphylococcus aureus ATCC 6538 (WDCM 00032)):
Colony count (Staphylococcus aureus ATCC 25923 (WDCM 00034)):
Recovery on test medium (Staphylococcus aureus ATCC 6538 (WDCM 00032)): ≥ 50 %
Recovery on test medium (Staphylococcus aureus ATCC 25923 (WDCM 00034)): ≥ 50 %
Growth (Escherichia coli ATCC 8739 (WDCM 00012)): no growth
Growth (Escherichia coli ATCC 25922 (WDCM 00013)): no growth
Growth (Staphylococcus saprophyticus ATCC 15305 (WDCM 00159)): no limit
Growth (Staphylococcus epidermidis ATCC 12228 (WDCM 00036)): no limit
Growth (Enterococcus hirae ATCC 8043 (WDCM 00089)): no limit
Growth (Proteus mirabilis ATCC 29906 (WDCM 00023)): no limit
Colonies (Staphylococcus aureus ATCC 6538 (WDCM 00032)): Black or grey colonies with clear halo
Colonies (Staphylococcus aureus ATCC 25923 (WDCM 00034)): Black or grey colonies with clear halo
Colonies (Staphylococcus saprophyticus ATCC 15305 (WDCM 00159)): Black or grey colonies without clear halo
Colonies (Staphylococcus epidermidis ATCC 12228 (WDCM 00036)): Black or grey colonies without clear halo
Colonies (Enterococcus hirae ATCC 8043 (WDCM 00086)): Black or grey colonies without clear halo
Colonies (Proteus mirabilis ATCC 29906 (WDCM 00023)): Brown or black colonies without clear halo
Incubation:
24 ± 2 to 48 ± 2 hours at 37 ± 1 °C aerobic
E.coli 48 ± 2 hours at 37 ± 1 °C aerobic
A recovery rate of 50 % is equivalent to a productivity value of 0.5.
The indicated colony counts result from the sum of a triple determination.
Reference media: Tryptic Soy Agar

Footnote

We offer two media types: the superior granulated GranuCult^® and the cost-efficient powdered NutriSelect^® culture media, depending on your needs.
The designations basic, plus, or prime are added to indicate the quality control level, from basic quality control to standard QC plus to prime for full regulatory compliance.

Legal Information

GRANUCULT is a registered trademark of Merck KGaA, Darmstadt, Germany

NutriSelect is a registered trademark of Merck KGaA, Darmstadt, Germany