DNASE TOLUIDINE BLUE AGAR

Technical Data #1551a / 2000.11.01

Dnase Toluidine Blue Agar is a solid differential medium used for detection of deoxyribonuclease of Staphylococcus aureus, Serratia marcescens and others microorganisms.
Toluidine Blue produces a clear halo around positive deoxyribonuclease.

FORMULA
in grams per liter purified filtered water

Casein Peptone

15,0

Soy Peptone

5,0

Deoxyribonucleic Acid

2,0

Sodium Chloride

5,0

Toluidine Blue

0,1

Agar

15,0

pH 7,2 +/- 0,2 à 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 or deterioration (shrinking, cracking, evaporation or discoloration). Do not use dehydrated media if it is caked.


DIRECTIONS
Suspend 42,1 g of dehydrated media in 1000 ml of purified filtered water. Heat with frequent agitation and boil for one minute. Sterilize at 121° C for 15 minutes. Mix thouroughly and dispense into sterile Petri dishes or culture tubes.


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

  1. Inoculate from an overnight growth with a straight line.
  2. Incubate at 35° C for 24 hours.


QUALITY CONTROL
Results after 24 hrs at 35ºC

Organisms

ATCC

Growth

Halc

Staphylococcus aureus

25923

+

+

Escherichia coli

25922

+

-

Serratia marcescens

13880

+

+

Streptococcus pyogenes

19615

+

+

Klebsiella pneumoniae

33495

+

-

A growth surrounded by clear zone is typical of positive deoxyribonuclease production. A negative result shows an homogenous blue medium.


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.
  3. Finegold, S.M., and W.J. Martin. 1984 Bailey's and Scott's Diagnostic Microbiology. 6th ed. St. Louis. The C.V. Mosby Company.
  4. Handbook of Microbiological Media 1997 2nd ed


CATALOGUE NUMBERS

Dehydrated media 500 grams QB-39-1119
Prepared media    
Plates, 100x15 mm 10/pkg 1551
Mono-Plates, 100x15 mm 10/pkg 1551M
Tubes, 13X100 mm 10/pkg 2271

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