BAIRD-PARKER AGAR

Cat. no. G96 Baird-Parker Agar, 15x100mm Plate, 18ml 10 plates/bag
Cat. no. P16 Baird-Parker Agar, 15x60mm Contact Plate*, 15ml 10 plates/bag
* P16 is a contact plate used for sampling environmental surfaces.

INTENDED USE

Hardy Diagnostics Baird-Parker Agar is a selective medium for the detection and enumeration of coagulase-positive staphylococci from food samples.(1)

Cat. no. P16 is not intended to be used for the diagnosis of human disease.

SUMMARY

Baird-Parker medium was developed by Baird-Parker to isolate and enumerate coagulase-positive staphylococci from foods. (3) The present formulation, by Baird-Parker, is a modification from a previous formula developed by Zebovitz, Evan, and Niven. (4) Sodium pyruvate was added as a selective growth stimulant, and egg yolk emulsion as a differentiation agent. The medium allows growth of Staphylococcus aureus and selectively inhibits growth of most other bacteria.

Selective inhibition is thought to be caused by the combination of the selective agents tellurite and lithium. Glycine and pyruvate are added to enhance the growth of staphylococci.

After 24 to 48 hours of incubation at 35-37ºC., colonies of S. aureus will appear black, convex, shiny, and 1-1.5mm in diameter. The very distinct black colonies formed by S. aureus are a result of the reduction of tellurite in the medium. These colonies will normally be surrounded by clear zones, a result of proteolysis or lipolysis. Occasionally, opaque zones will form within this clear zone, a result of lipase or lecithinase activity. Other bacteria which may grow on this medium are easily distinguished from S. aureus , as they do not form black colonies.

FORMULA

Ingredients per 940ml of deionized water:*

Glycine 12.0gm
Pancreatic Digest of Casein 10.0gm
Sodium Pyruvate 10.0gm
Beef Extract 5.0gm
Lithium Chloride 5.0gm
Yeast Extract 1.0gm
Egg Yolk Tellurite Enrichment 60.0ml
Agar 20.0gm

Final pH 7.0 +/- 0.2 at 25ºC.

* Adjusted and/or supplemented as required to meet performance criteria.

STORAGE AND SHELF LIFE

Storage: Upon receipt store at 2-8ºC. away from direct light. Media should not be used if there are any signs of deterioration (shrinking, cracking, or discoloration), hemolysis, contamination, or if the expiration date has passed. Product is light and temperature sensitive; protect from light, excessive heat and freezing.

PRECAUTIONS

For Cat. no. G96.

For Cat. no. P16.

PROCEDURE

Specimen Collection: Infectious material should be submitted directly to the laboratory without delay and protected from excessive heat and cold. If there is to be a delay in processing, the specimen should be inoculated onto an appropriate transport media and refrigerated until inoculation. Consult listed references for information on specimen collection. (1-4)

Method of Use: The plates should be warmed to room temperature and the agar surface should be dry before inoculating. Inoculate the specimen onto the media as soon as possible after it is received in the laboratory. If the material is being cultured from a swab, roll the swab over a small area of the agar surface and streak for isolation. Incubate plates aerobically at 35-37ºC. for 24 to 48 hours. Observe plates for characteristic colonial morphology and color at 24 hours. If negative for staphylococci, reincubate for an additional 24 hours and read again.

INTERPRETATION OF RESULTS

The presence of black, convex, shiny colonies 1-1.5mm in diameter is a presumptive positive test for the presence of S. aureus . Colonies which do not form the black pigmentation should be interpreted as negative.

LIMITATIONS

Coagulase-negative staphylococci generally do not grow well on Baird-Parker Agar; if some growth occurs, the typical clear zones are absent. Proteus or Bacillus species may also grow but appear as brown colonies.

MATERIALS REQUIRED BUT NOT PROVIDED

Standard microbiological supplies and equipment such as loops, other culture media, swabs, applicator sticks, incinerators, and incubators, etc., as well as serological and biochemical reagents, are not provided.

QUALITY CONTROL

Test Organisms Inoculation Method* Incubation Results
Time Temperature Atmosphere
Staphylococcus aureus
ATCC ® 25923
A 24hr 35°C Aerobic Growth; black shiny colonies with clear halo
Proteus mirabilis
ATCC ® 12453
A 24hr 35°C Aerobic Growth; brown colonies
Escherichia coli
ATCC ® 25922
B 24hr 35°C Aerobic Partial to complete inhibition

User Quality Control

PHYSICAL APPEARANCE

Baird-Parker Agar should appear opaque, and light yellow in color with no precipitate, chips or debris.

S. aureus growing on Baird-Parker Agar

Staphylococcus aureus (ATCC ® 25923) colonies growing on Baird-Parker Agar (Cat. no. G96). Incubated aerobically for 24 hours at 35ºC.

P. mirabilis growing on Baird-Parker Agar

Proteus mirabilis (ATCC ® 12453) colonies growing on Baird-Parker Agar (Cat. no. G96). Incubated aerobically for 24 hours at 35ºC.

E. coli inhibited on Baird-Parker Agar

Escherichia coli (ATCC ® 25922) growth inhibited on Baird-Parker Agar (Cat. no. G96). Incubated aerobically for 24 hours at 35ºC.

REFERENCES

1. Association of Official Analytical Chemists. Official Methods of Analysis,. AOAC, Washington, D.C

2. Baird-Parker. 1962. J. Appl. Bact.; 25:12.

3. Jorgensen., et al. Manual of Clinical Microbiology, American Society for Microbiology, Washington, D.C.

4. Zebovitz, Evan, et al. 1955. J. Bact.; 70:686.


ATCC is a registered trademark of the American Type Culture Collection.

121415hh