NINHYDRIN REAGENT

Cat. no. Z70 Ninhydrin Reagent 15ml

INTENDED USE

Hardy Diagnostics Ninhydrin Reagent is recommended for use in rapid determination of sodium hippurate hydrolysis reactions in bacteria.

SUMMARY

The hippurate test is a qualitative procedure for determining the ability of group B streptococci, as well as other bacteria, to hydrolyze sodium hippurate to benzoic acid and glycine. The development of a purple color after the addition of ninhydrin indicates the splitting of hippurate by the detection of glycine.

REAGENT FORMULA

Ingredients per liter:*

Ninhydrin 35.0gm
Acetone 500.0ml
Butanol 500.0ml

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

STORAGE AND SHELF LIFE

Upon receipt store at 2-30ºC. Reagent is light sensitive; protect from light. Products should not be used if there are any signs of deterioration or if the expiration date has passed.

PRECAUTIONS

Warning: Flammable - Keep away from heat and flames. Use adequate ventilation.

PROCEDURE

Specimen Collection: This product is not intended for primary isolation of patient specimens. This product is used in conjunction with other biochemical tests to identify cultures of isolated organisms.

Method of Use: Heavily inoculate 0.4ml of sodium hippurate broth with 18-24 hour culture of the test organism. Concurrent inoculation of positive and negative control organisms is also recommended. Incubate two (2) hours at 35ºC. Add five (5) drops of Ninhydrin Reagent, mix well. Reincubate tubes 10-15 minutes and read reaction.

INTERPRETATION OF RESULTS

A positive hippurate reaction is denoted by the appearance of a deep purple-blue color. A negative hippurate reaction is indicated by a light purple color or no color change.

Note: Do not incubate longer than 30 minutes because a false-positive reading could result.

LIMITATIONS

Rapid sodium hippurate hydrolysis reactions may be used in the presumptive identification of group B beta-hemolytic streptococci. Additional testing, using pure culture, is recommended for complete identification.

Some strains of group D streptococci may give a weak positive result. Group D can be differentiated from group B by esculin hydrolysis. Only group D streptococci hydrolyze esculin yielding a blackening of the medium.

Incubation of test culture for more than 30 minutes after the Ninhydrin Reagent is added can yield false-positive results.

MATERIALS REQUIRED BUT NOT PROVIDED

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

QUALITY CONTROL

Test Organisms Reaction
Streptococcus agalactiae
ATCC ® 12386
Positive; purple color change
Streptococcus pyogenes
ATCC ® 19615
Negative; no color change

User Quality Control

It is recommended that each new lot of reagent be tested with known positive and negative controls and retested at least each week of use thereafter. (3)

PHYSICAL APPEARANCE

Ninhydrin Reagent should appear clear, colorless to light yellow.

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

5. Koneman, E.W., et al. Color Atlas and Textbook of Diagnostic Microbiology, J.B. Lippincott Company, Philadelphia, PA.

6. MacFaddin, J.F. Biochemical Tests for Identification of Medical Bacteria,, Lipincott Williams & Wilkins, Philadelphia, PA.


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

032816gr