Thermo Scientific™ MRVP Broth

Description

• Identify and differentiate amongst coli-aerogene groups using Thermo Scientific™ Remel™ MR-VP Broth
• In 1898, Voges and Proskauer reported the production of a red color after the addition of potassium hydroxide to cultures grown on an appropriate medium 1
• Later Barritt made the VP test more sensitive by addition of alpha naphthol to the medium 2
• In 1915, Clarke and Lubs first described the methyl red test in differentiating between the coli-aerogenes group of enteric bacteria 3
• Further MR-VP broth was developed to permit both tests to be performed using the same medium
• All members of Enterobacteriaceae are, by definition, glucose fermenters, resulting in the production of acid
• MR-VP Broth is recommended for use in qualitative procedures for the performance of Methyl Red (MR) and Voges-Proskaur (VP) test as an aid in the identification of enteric gram-negative bacilli
• Both MR and VP tests can be performed in the same medium
• Easy-to-differentiate: MR positive organisms show a red color development and VP positive organisms produce a pink-red color development, while MR and VP negative organisms produce yellow color on the surface of the medium
• Ready-to-use : Convenience of prepared media
• The MR test is based on the use of a pH indicator, methyl red, to determine the hydrogen ion concentration present when an organism ferments glucose 4
• This medium contains buffered peptone water, which supports growth of organisms
• MR-positive organisms continue to produce acids, overcoming the phosphate buffer and resulting in a low pH and a red color development
• MR-negative organisms further metabolize the initial fermentation products by decarboxylation to produce neutral acetyl methyl carbinol (acetoin), which results in a neutral pH
• The VP test is based on the detection of neutral end-product acetylmethylcarbinol derived from glucose metabolism and is used primarily to separate Escherichia coli (VP negative) from the Klebsiella-Enterobacter group (VP positive)
• Acetylmethylcarbinol is a precursor to 2,3-butanediol, both of which are oxidized to diacetyl which is the reactant for the pink-red color produced in the VP test 5
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• Remel™ and Oxoid™ products are now part of the Thermo Scientific brand.