A specialized microbiological medium called Baird Parker Agar (BPA) was created by Baird-Parker in 1962 specifically for the purpose of isolating and counting Staphylococcus aureus. Because of its great selectivity and differential qualities, it has now established itself as a standard medium that is often used in food microbiology, clinical diagnostics, and environmental monitoring.
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Definition of Baird Parker Agar
The purpose of Baird Parker Agar (BPA) is to isolate and count Staphylococcus aureus from culinary, environmental, and clinical samples. It is a selective and differential microbiological growing medium.
Baird Parker Agar Composition
`1. Tryptone: 10.0 g
a supply of vitamins, amino acids, and nitrogen that are necessary for the development of bacteria.
2. Yeast Extract: 5.0 g
provides vitamins in the B complex, which promote the development of microorganisms.
3. Glycine: 12.0 g
enhances the non-target organisms’ selective inhibition.
4. Sodium Pyruvate: 10.0 g
helps stressed Staphylococcus aureus cells grow and recover.
5. Lithium Chloride: 5.0 g
prevents the development of undesirable microorganisms, especially those that are Gram-negative.
6. Potassium Tellurite (added separately as a 1% solution): 10.0 ml
a selective agent that gives colonies of Staphylococcus aureus their characteristic black color while inhibiting a large number of non-target organisms.
7. Egg Yolk Emulsion (added separately): 50.0 ml
provides lipids and lecithin for the measurement of Staphylococcus aureus-specific lipase and lecithinase activities.
8. Agar: 20.0 g
the solidifying ingredient that creates the medium’s gel matrix.
9. Sodium Chloride: 5.0 g
preserves the medium’s osmotic equilibrium.
10. Phenol Red: 0.025 g
a pH indicator that makes it easier to see how the pH fluctuates while bacteria grow.
Principle of Baird Parker Agar
1. Parker Baird Staphylococcus aureus is necessary for Agar to be able to:
Reduce tellurite (resulting in black colonies).
Provoke proteolysis of egg yolk (creating a clear halo around colonies).
Render the proteolysis zone opaque (due to lipase activity).
2. While glycine and pyruvate encourage the growth of Staphylococci, lithium chloride and tellurite restrict the establishment of alternate microbial flora in the medium.
3. While certain Staphylococci are not always able to decrease tellurite, which results in black colonies, nearly all coagulase-positive Staphylococci are capable of doing so.
4. By exhibiting lecithinase activity, the egg yolk additive facilitates identification (egg yolk reaction).
5. Coagulase-positive Staphylococci may be identified using this medium by a clear zone and colonies that are grey-black in color.
Preparation of Baird Parker Agar
- The necessary quantity of the dehydrated media should be suspended in distilled water.
- Bring to a boil while stirring to fully dissolve the medium.
- Use an autoclave set at 121°C for 15 minutes to sterilize.
- Reduce temperature to 45–50°C.
- Rehydrated egg yolk emulsion and potassium tellurite solution should be added aseptically.
- After fully combining, transfer to sterilized Petri dishes.
Results of Baird Parker Agar
- Staphylococcus aureus: Produces black, shiny colonies with clear zones due to tellurite reduction and lecithinase activity, often surrounded by opaque zones of precipitation from lipase activity.
- Non-target organisms: Usually inhibited or do not produce the characteristic colony morphology of Staphylococcus aureus.
Uses of Baird Parker Agar
- Staphylococcus aureus is isolated from dietary, environmental, and clinical samples.
- Enumeration: Beneficial for food and cosmetic quality monitoring.
- In industrial microbiology, contamination detection is very important when it comes to products that may contain Staphylococcus aureus.
Frequently Asked Question
1. What is the Baird-Parker Agar used for?
Using the Baird Parker technique, coagulase-positive staphylococci in food and medicine are isolated and differentiated using Baird Parker Agar. In the medium, casein peptone and meat extract are added as a source of nitrogen for the organism.
2. What is the principle of BPA agar?
A high correlation has been found between the coagulase test and the presence of a clear zone of lipolysis in this medium, which is due to the lecithinase of Staphylococci that breakdown, the egg yolk
3. Why is BPA used?
Food packaging materials can safely include BPA to increase shelf life and guard against contamination and spoiling. What occurs inside the human body when tiny levels of BPA are eaten is explained by scientific studies.
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