DNase AGAR

Technical Data #1282a / 98.05.04

DNase Agar is a differential solid medium used to determine production of deoxyribonuclease activity by Staphylococcus aureus, Serratia marcescens and some others organisms. Addition of HCl after incubation of the medium, gives light zone, if depolymerization of DNA has happened.

FORMULA
in grams per liter purified filtered water

Casein Peptone	15,0
Soy Peptone	5,0
Deoxyribonucleic Acid	2,0
Sodium Chloride	5,0
Agar	15,0

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 42 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.

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

1. Inoculate plates in a straight line with a 24 hours-diluted broth culture.
2. Incubate at 35º C for 24 hours.
3. Pour 0,1N Hydrochloric Acid on the surface of the medium. Colourless zones within a few minutes, indicate DNase production by the colonies, while opaque zone gives a negative result.

QUALITY CONTROL
Results after 24 hrs at 35ºC

Organisms	ATCC	Growth	Clear Zone
Staphylococcus aureus	25923	+	+
Escherichia coli	25922	+	-
Serratia marcescens	13880	+	+
Streptococcus pyogenes	19615	+	+
Klebsiella pneumoniae	33495	+	-

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-dentification-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.

CATALOGUE NUMBERS

Dehydrated media	500 g	QB-39-1118
Prepared media
Plates, 100x15 mm	10/pkg	1282
Mono-Plates, 100x15 mm	10/pkg	1282M

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