M.R.- V.P. (METHYL RED-VOGES PROSKAUER) BROTH

Technical Data #2120a / 2013.06.23

MR-VP Broth is a liquid medium used for differentiation between genera or in species differentiation within a genus by means of methyl red and Voges Proskauer reactions. The test is of particular value in differentiating the Klebsielleae from Escherichieae.

 


 

FORMULA
in grams per liter purified filtered water

Casein Peptone

3,5

Meat Peptone

3,5

Dextrose

5,0

Potassium Phosphate, dibasic

5,0

pH 6,9 +/- 0,2 25 C

This approximate formula may be adjusted and/or enriched to obtain best results.


PRECAUTIONS
This medium is for IN VITRO diagnostic use only.


STORAGE
Store prepared media at 2-8 C protected from direct light and dehydrated powder, in a dry place in tightly-sealed containers at 2-25 C.


SIGN OF DETERIORATION
Media should not be used if the expiry date has passed. Prepared media should not be used if there are signs of contamination (evaporation or discoloration). Do not use dehydrated media if it is caked.


DIRECTIONS
Suspend 17 g in 1000 ml of purified water. Heat with frequent agitation and boil for one minute. Mix thouroughly and dispense into culture tubes. Sterilize at 121 C for 15 minutes.


PROCEDURE
Bring prepared medium at room temperature before inoculation.

  1. Inoculate with 1-2 similar colonies from an overnight growth.
  2. Incubate at 35 C for 24 hours.
  3. VP test: to an aliquot of 1 ml, add 6 drops of -naphtol (8557) followed by 3 drops of KOH 40% (8558). Mix thouroughly and let stand for 15 minutes.
  4. Reincubate the remaining broth for another 24 hours to perform MR test.
  5. MR test: add 5-7 drops of Methyl Red reagent (8573). Positive result: red color. Negative result: no change in color.


QUALITY CONTROL

Expected results after 24-48 hrs at 35C

Organisms

ATCC

M.R.

V.P.

Escherichia coli

25922

+

-

Enterobacter aerogenes

13048

-

+


LIMITATIONS OF METHOD
MR test should not be made before 48 hours incubation. VP test may be heat gently after reagents addition if a negative result appears. This is only a part of the identification. Others tests may be required.


REFERENCES

  1. Ewing, W.H., 1986 Edwards and Ewing's identification of Enterobacteriaceae 4th ed. Elsevier Science Publishing Co, New York
  2. Lennette, E.H., Ballows, A., Hausler, W.J.Jr., and Shadomy, H.J. Manual of Clinical Microbiology. 4th ed. 1985 Washington D.C.: American society for Microbiology.
  3. Mac Faddin, Jean F. 1985 Media for Isolation-Cultivation-Identification-Maintenance of Medical Bacteria. Vol. I, Baltimore, MD.: Williams & Wilkins.
  4. Washington, J.A. 1981 Laboratory procedures in clinical microbiology. Springer-Verlag, New York


CATALOGUE NUMBERS

Dehydrated media 500 g QB-39-3106
     
Prepared media    
Tubes 16x125 mm, 5 ml 10/pkg 2120
     
1-Naphtol Reagent 30 ml 8557
     
KOH 40% Reagent 30 ml 8558
     
Methyl Red Reagent 30 ml 8573

 


 

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