PHENYLALANINE AGAR

Technical Data #2638a / 2013.06.30

Phenylalanine Agar is a solid medium used to differentiate Proteus sp. and Providencia sp. from ohter Enterobacteriaceae by their ability to deaminate phenylalanine to phenylpyruvic acid by enzymatic activity. A positive result gives a characteristic dark green color when ferric chloride reagent is added to a pure culture growth.

 


 

FORMULA
in grams per liter purified filtered water

Yeast Extract

3,0

DL-Phenylalanine

2,0

Sodium Chloride

5,0

Potassium Phosphate, dibasic

1,0

Agar

12,0

pH 7,3 +/- 0,2 à 25º 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 2-8º C protected from direct light and dehydrated powder, in a dry place, in tightly-sealed containers at 2-25º 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 or deterioration (shrinking, cracking, evaporation or discoloration). Do not use dehydrated media if it is caked.


DIRECTIONS
Suspend 23 g of dehydrated media in 1000 ml of purified filtered water. Heat with frequent agitation and boil for one minute. Sterilize at 121º C for 15 minutes. Cool to 45-50º C. Mix gently and dispense into sterile culture tubes.


PROCEDURE
Prior to inoculate, the prepared media should be brought to room temperature.

  1. Prepare a solution from an overnight culture with 2-3 similar colonies.
  2. Inoculate tubes using a fishtail motion
  3. Incubate at 35º C for 4-24 hours depending of inoculum concentration.
  4. Add a few drops of ferric chloride solution.


QUALITY CONTROL

Results after 24 hrs at 35ºC

Organisms

ATCC

Color

Proteus mirabilis

12453

green

Proteus vulgaris

8427

green

Escherichia coli

25922

no change


LIMITATIONS OF METHOD
This medium is only a part of the identification. Other tests may be required.


REFERENCES

  1. Edwards, P.R., W.H. Ewing 1972 Identification of Enterobacteriaceae 3rd ed Burgess Publishing, Minneapolis
  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., Media for Isolation-Cultivation-Identification-Maintenance of Medical Bacteria Vol.1 1985 Baltimore, MD. Williams & Wilkins.
  4. Singer, J., Volcani, B.E., 1955 An improved ferric chloride test for differentiating Proteus-Providence group from other Enterobacteriaceae. J. Bacteriol. 69:255


CATALOGUE NUMBERS

Dehydrated media 500 g QB-39-3525
     
Prepared media    
Tubes, 16x125 mm 10/pkg 2638
Tubes, 13x100 mm 10/pkg 2742

 


 

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