RAPID UREA MEDIUM

Cat. no. Z54 Rapid Urea Medium, 15x45mm Vial, 2ml Deep 10 tubes/box
Cat. no. R154 Rapid Urea Medium, 13x100mm Tube, 3ml 20 tubes/box

INTENDED USE

Hardy Diagnostics Rapid Urea Medium is used for the rapid determination of urease activity in bacteria such as Proteusspp., Helicobacter pylori, or in yeast, such as Cryptococcus neoformans.

SUMMARY

Urease activity can be described as the splitting of urea via hydrolysis by a urease enzyme. The end products from this reaction yield ammonium carbonate and ammonia, which are alkaline in nature. Organisms that possess this urease enzyme may be characterized by this activity in a specific, yet rapid test formulated by Goldie.(4) The test is non-toxic, and the pH change that occurs from accumulation of alkaline end products is detected by a pH indicator in the media. Helicobacter pylori is an organism that may be easily identified by this test because of its very high endogenous urease activity. This method has been used to help simplify the diagnosis of H. pylori, especially those specimens originating from duodenal and gastric ulcers, and chronic antral gastritis (type B). The urease reaction obtained from H. pylori in Rapid Urease Medium occurs more quickly than that seen by other organisms which may split urea. As a result, it is an effective presumptive test for the presence of H. pylori.

REAGENT FORMULA

Ingredients per liter of deionized water:*

Urea 20.0gm
Monosodium Phosphate 0.7gm
Phenol Red 0.1gm
Agar 4.0gm

Final pH 6.0 +/- 0.2 at 25ºC. Final pH for Cat. no. R154 is 6.9 +/- 0.1 at 25ºC.

* Adjusted and/or supplemented as required to meet performance criteria.

STORAGE AND SHELF LIFE

Upon receipt store at 2-8ºC away from direct light. Media should not be used if there are any signs of contamination, deterioration, (shrinking, cracking or discoloration) or if the expiration date has passed. Product is light and temperature sensitive; protect from light, excessive heat, moisture, and freezing.

PRECAUTIONS

PROCEDURE

Isolated Organism: Using a sterile wooden applicator stick or platinum loop, obtain a loopful of a 24-48 hour old isolated organism from a non-selective agar plate (such as Chocolate Agar, Cat. no. E14). Inoculate the media by stabbing. Incubate at room temperature (15-30ºC) aerobically. Observe at 15-20 minutes and again at one, three, and six hours of incubation for the development of a pink-red or red-violet color. Continue incubation of negative tests for up to 20 hours. Rapid Urea Medium may be incubated at 35ºC. in order to obtain faster reaction times.

Biopsy Specimen: Biopsy specimens are to be placed in 0.5ml of lactated Ringers solution at pH 6.5. Transport to laboratory on wet ice. Consult appropriate references for detailed directions on specimen collection.

Grind biopsy specimens with a sterile tissue grinder, and place a portion of the ground specimen into the Rapid Urea Medium. As an alternative to this method, the biopsy may be placed directly into the Rapid Urea Medium at the time of endoscopy, if desired. Submerge the specimen in the Rapid Urea Medium. Incubate at room temperature (15-30ºC.) aerobically. Observe at 15-20 minutes and again at one, three, and six hours of incubation for the development of a pink-red or red-violet color. Continue incubation of negative tests for up to 20 hours. Rapid Urea Medium may be incubated at 35ºC in order to obtain faster reaction times.

INTERPRETATION OF RESULTS

A positive reaction is indicated by the appearance of a pink-red to violet color. No color change is indicative of a negative reaction. A strong positive reaction may be determined within minutes of inoculation into the Rapid Urea Medium.

LIMITATIONS

Nichrome inoculating loops can generate an immediate false-positive result. A sterile wooden stick or a platinum loop should be used to transfer the specimen into the Rapid Urea Medium vial.

MATERIALS REQUIRED BUT NOT PROVIDED

Standard microbiological supplies and equipment such as loops, incinerators, incubators, forceps, etc., as well as serological and biochemical reagents, are not provided.

QUALITY CONTROL

Test Organisms Results
Proteus mirabilis
ATCC® 12453
Positive; color change from the original yellow to pink-red, slower reaction time than H. pylori
Escherichia coli
ATCC® 25922
Negative; no color change observed

User Quality Control

PHYSICAL APPEARANCE

Rapid Urea Medium should appear slightly hazy, and bright yellow to yellowish-orange in color. Do not use if media appears pink-red.

Positive Urease Reaction

Proteus mirabilis (ATCC® 12453) in Rapid Urea Medium (Cat. no. Z54). The pink-red color development was indicative of a positive urease reaction. Incubated aerobically at room temperature for one hour. A stronger reaction will be observered after longer incubation. Alternatively, incubation can be conducted at 35ºC. for faster reaction.

Negative Urease Reaction

Escherichia coli (ATCC® 25922) in Rapid Urea Medium (Cat. no. Z54). No pink-red color development was indicative of a negative urease reaction. Incubated aerobically at room temperature for 20 hours.

REFERENCES

1. Jorgensen., et al. Manual of Clinical Microbiology, American Society for Microbiology, Washington, D.C.

2. Tille, P., et al. Bailey and Scott's Diagnostic Microbiology, C.V. Mosby Company, St. Louis, MO.

3. Anderson, N.L., et al. Cumitech 3B; Quality Systems in the Clinical Microbiology Laboratory, Coordinating ed., A.S. Weissfeld. American Society for Microbiology, Washington, D.C.

4. Goldie, J., et al. 1989. Optimization of medium for rapid urease test for detection of Campylobacter pylori in gastric antral biopsies. J. Clin. Microbiol.; 27:2080-2082.

5. Pique, J.M., et al. 1989. Notes: Rapid detection of gastric Campylobacter pyloricolonization by a simple biochemical test.J. Clin. Microbiol.; 27:2604-2605.

6. Isenberg, H.D. Clinical Microbiology Procedures Handbook, Vol. I, II & III. American Society for Microbiology, Washington, D.C.

ATCC is a registered trademark of the American Type Culture Collection.

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