How do you make Simmons citrate agar?

Preparation of Simmons Citrate Agar

1. Dissolve above salts in deionized water.
2. Adjust pH to 6.9.
3. Add agar and Bromothymol blue.
4. Gently heat, with mixing, to boiling until agar is dissolved.
5. The medium may be used either as slopes in test tubes or as a plate medium in petri dishes.

What is in Simmons citrate agar?

Simmons citrate agar contains sodium citrate as the sole source of carbon, ammonium dihydrogen phosphate as the sole source of nitrogen, other nutrients, and the pH indicator bromthymol blue. This test is part of the IMViC tests and is helpful in differentiating the Enterobacteriaceae .

Why must Simmons citrate incubate for 7 days?

Incubate aerobically at 35°C to 37°C for 18 to 24 hours. Some organisms may require up to 7 days of incubation due to their limited rate of growth on citrate medium.

Is Simmons citrate medium a selective medium?

Simmons’ citrate agar is a selective and differential medium that tests for an organism’s ability to use citrate as a sole carbon source and ammonium ions as the sole nitrogen source. It is useful for selecting organisms that use citrate as its main carbon and energy source.

What is Simmons citrate agar used for?

Simmons Citrate Agar is used for the differentiation of microorganisms on the basis of citrate utilization in a laboratory setting. Simmons Citrate Agar is not intended for use in the diagnosis of disease or other conditions in humans.

Is E coli citrate positive?

Klebsiella pneumoniae and Proteus mirabilis are examples of citrate positive organisms. Escherichia coli and Shigella dysenteriae are citrate negative.

What does a positive citrate test indicate?

Thus citrate-negative bacteria can also grow on this medium. A positive reaction shows that the organism can use citrate but not necessarily as the sole carbon source.

What is Simmons citrate used for?

Simmons’ citrate agar is used for differentiating gram-negative bacteria on the basis of citrate utilization. It is useful for selecting for organisms that use citrate as its main carbon and energy source.

What does a positive and negative citrate test mean?

Positive Reaction: Growth with color change from green to intense blue along the slant. Examples: Salmonella, Edwardsiella, Citrobacter, Klebsiella, Enterobacter, Serratia, Providencia, etc. Negative Reaction: No growth and No color change; Slant remains green.

Is Simmons citrate agar selective or differential?

Simmons’ citrate agar is a selective and differential medium that tests for an organism’s ability to use citrate as a sole carbon source and ammonium ions as the sole nitrogen source. It is used for differentiating gram-negative bacteria on the basis of citrate utilization.

What is citrate agar test?

Citrate agar is used to test an organism’s ability to utilize citrate as a source of energy. The medium contains citrate as the sole carbon source and inorganic ammonium salts ( NH4H2PO4 ) as the sole source of nitrogen.

What is Simmons citrate?

Simmons Citrate Agar is an agar medium used for the differentiation of Enterobacteriaceae based on the utilization of citrate as the sole source of carbon.

What is the purpose of the citrate test?

The citrate test detects the ability of an organism to use citrate as the sole source of carbon and energy.