B.C.P. DEXTROSE MILK AGAR

Technical Data # 2667 / 2010.08.09

B.C.P. Dextrose Milk agar is a solid medium used for differentiation of Trichophyton mentagrophytes and Trichophyton rubrum. A blue positive reaction is obtained with Trichophyton mentagrophytes.

 

FORMULA

in grams per litre purified filtered water

 

Skim milk .....................................................40,0

Dextrose ......................................................20,0

Brom cresol purple  ........................................0,016

Agar ..............................................................15,0

pH 6,8 +/- 0,2 at 25º C

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


PRECAUTIONS
This medium is for laboratory 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 or deterioration (shrinking, cracking, evaporation or discoloration). Do not use dehydrated media if it is caked.

DIRECTION

Suspend 40 g of skim milk and 0,016g of brom cresol purple in 500 ml of purified filtered water. Sterilize at 121° C for 5 minutes. Cool to 45-50° C. Also suspend 20g of dextrose and 15,0 g of agar in 500 ml. Heat with frequent agitation and boil for one minute. Sterilize at 121° C for 15 minutes. Cool to 45-50° C. Aseptically put the two solutions together and mix gently. Dispense into slant tubes for solidification.

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

  1. Directly, inoculate the surface of medium with same colonies.
  2. Incubate at 35° C for 7 days.

QUALITY CONTROL                                         

Résultats après 3 jours à 25ºC

Results after 3 days at 25ºC

Organisms                             ATCC                      Growth

Trichophyton mentagrophytes    9533              + alkalin blue

Trichophyton rubrum                28188                     -

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)    Summerbell, R.C., S.A. Rosenthal & J. Kane. 1988 Rapid Method of differentiation of Trichophyton rubrum, Trichophyton mentagrophytes and related dermatophyte species .  J. Clin. Microbiol. 26 :2279-2282

3)   Kane, J., and C.Smitka. 1978 Early detection and identification of Trichophyton verrucosum. J. Clin. Microbiol. 8: 740-747

CATALOGUE NUMBERS

Deshydrated medium

Skim milk, powder                    500 g                QB-39-3809

Dextrose                                 500 g                QB-39-1210

Agar                                      500 g                QB-39-0221

Brom cresol purple                   25 g                  QB-63-0515

Prepared medium

Tubes, 16x125 mm                  10/pkg              2667