POTATO DEXTROSE AGAR

Technical Data #1571a / 98.05.21

Potato Dextrose Agar is a solid medium used for isolation, cultivation of yeasts and molds and to stimulate sporulation.

 

FORMULA
in grams per liter purified filtered water

 

Potato, Infusion from

4,0
Dextrose

20,0
Agar

17,0

pH 5,6 +/- 0,2 at 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 39 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 Petri dishes. To adjust pH at 3,5, add 10 ml of sterile Tartaric Acid Solution at 10% (8591).


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

  1. Directly, inoculate plates and streak for isolated colonies. Inoculate each specimen in duplicate.
  2. Incubate a set at 35º C and the other set at 25º C for 7 days.
  3. For sporulation, streak a part of the plate and cover with a cover slip.
  4. Incubate at 25º C until stimulation of spores.
  5. Transfer cover slip on a slide containing few drops of Lactophenol Blue.
  6. Examine at low power.


QUALITY CONTROL
Results after 7 days at 25ºC

 

Organisms

ATCC

Growth
Candida albicans

60193

+
Trichophyton mentagrophytes

9533

+

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


REFERENCES

  1. 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.
  2. Mac Faddin, Jean F., Media for Isolation-Cultivation-Identification-Maintenance of Medical Bacteria Vol.1 1985 Baltimore, MD. Williams & Wilkins.


CATALOGUE NUMBERS

 

Dehydrated media 500 g QB-39-3606
Prepared media    
Tubes 10/pkg 2782
Plates, 100x15 mm pH 3,5, pH 5,6 10/pkg 1571, 1071

Plates, 100x15 mm

Contact plate 

10/pkg

10/pkg

1216

1193