Which bacteria are citrate positive

Examples: Escherichia, Shigella, Morganella, Yersinia etc. Hi, may I know what might be the possible reason that e coli caused the blue color of the citrate test? Save my name and email in this browser for the next time I comment.

Preparation Dissolve above salts in deionized water. Adjust pH to 6. Add agar and Bromothymol blue. Gently heat, with mixing, to boiling until agar is dissolved. Dispense 4. Autoclave at degree C under 15 psi pressure for 15 minutes. Gram-negative bacilli, catalase positive, oxidase negative, motile, urease negative, citrate negative, indole positive, lactose fermenting, gas positive, hydrogen sulphide negative.

Gram-negative bacilli, catalase positive, oxidase negative, citrate positive, lactose non-fermenting, indole negative, nonmotile, gas negative, hydrogen sulphide negative. Gram-negative bacilli, oxidase negative, catalase positive, lactose fermenting, indole negative, motile, urease differential, hydrogen sulphide positive, gas positive, citrate positive.

Gram-negative bacilli, oxidase negative, catalase positive, lactose non-fermenting, indole positive, motile, urease differential, hydrogen sulphide negative, gas positive, citrate positive. Gram-negative bacilli, oxidase negative, catalase positive, lactose non-fermenting, indole negative, motile, urease positive, hydrogen sulphide positive, gas positive, citrate positive.

At pH 7. In addition, ammonium hydroxide is produced when the ammonium salts in the medium are used as the sole nitrogen source, which also helps to increase medium pH.

Growth usually results in the bromothymol blue indicator, turning from green to blue. The bromothymol blue pH indicator is deep forest green at neutral pH. With an increase in medium pH to above 7. In the citrate utilization test, the citrate medium most commonly used is the formula of Simmons. The medium is poured into a tube on a slant.

The composition of Simmons citrate agar is as follows:. Citrate positive: growth will be visible on the slant surface and the medium will be an intense Prussian blue. The alkaline carbonates and bicarbonates produced as by-products of citrate catabolism raise the pH of the medium to above 7. Citrate negative: trace or no growth will be visible. No color change will occur; the medium will remain the deep forest green color of the uninoculated agar. Only bacteria that can utilize citrate as the sole carbon and energy source will be able to grow on the Simmons citrate medium, thus a citrate-negative test culture will be virtually indistinguishable from an uninoculated slant.

Although uncommon, natural E. Citrate-negative strains of E. Citrate utilization test is often used as a part of a battery of tests IMViC used to identify gram-negative pathogens of the Enterobacteriaceae family. Last updated on June 21st, Shigellae are Gram-negative, non-motile, non-spore-forming, rod-shaped highly infectious bacteria of the Enterobacteriaceae family.

Shigella species include; Shigella sonnei, S. Contents1 Classification2 Diseases2. Last updated on June 25th, Klebsiella pneumoniae is a Gram-negative rod-shaped bacteria of genus Klebsiella and the family Enterobacteriaceae. They are members of normal intestinal flora of humans and animals and may be isolated from a variety of […].