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PYR Test Kit

Hardy Diagnostics PYR Test Kit and PYR Reagent are recommended for the detection of pyrolidonyl arylamidase (also called pyrolidonyl aminopeptidase) activity in certain groups of bacteria.


PYR is a rapid colorimetric method for presumptive identification of certain groups of bacteria based on the activity of the enzyme pyrolidonyl arylamidase. L-pyroglutamic acid beta-naphthylamide is impregnated into the test disk and serves as the substrate for the detection of pyrolidonyl arylamidase. Hydrolysis of the substrate yields beta-naphthylamide which combines with the PYR Reagent (p-dimethylamino-cinnamaldehyde) to form a bright pink to cherry red color. A positive PYR tests allows for the presumptive identification of group A streptococci (Streptococcus pyogenes) and group D enterococci. In addition, investigators have determined that PYR activity is a key test for differentiation of some species of coagulase-negative Staphylococcus and for some genera of the family Enterobacteriaceae.


The PYR Test Kit contains disks impregnated with L-pyroglutamic acid beta-naphthylamide and a reagent bottle of chromogenic solution (PYR Reagent); 0.015% p-dimethylaminocinnamaldehyde.


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

Method of Use:

The Chromogenic Solution (PYR Reagent) is designed for use in the PYR Test Kit or with the StrepQuick™ (Cat. no. HDZ122). Moisten the PYR Disk slightly with distilled or deionized water. Do not saturate.

Alternatively, the disk may be placed on a blood agar plate, which will adequately moisten the disk. Using a sterile loop, pick 2-3 well isolated, 18-24 hour colonies (grown on a non-selective media such as Blood Agar, Cat. no. A10) and rub into a small area of the PYR Disk so that there is a visible paste. After the test organism has been inoculated onto the disk, allow it to react for two minutes. After this incubation period add one drop of Chromogenic Solution (PYR Reagent)

.Note: Refer to the HUGO™ technical information sheet for StrepQuick™ for procedural use and interpretation of results.


A bright pink or cherry red color will appear within one minute if the test is positive. A negative test is indicated by no color change. The development of an orange, salmon, or yellow color should be interpreted as a negative reaction.

Organisms expected to give a positive result:

Group A streptococci (Streptococcus pyogenes)

Group D enterococci (Enterococcus spp.)

Coagulase-negative Staphylococcus spp.: haemolyticus, lugdunensis and schleiferi

Citrobacter, Klebsiella, Yersinia, Enterobacter and Serratia spp.  

Cat. no. HDZ75 / HDZ175

Size: 20 tests / 100 tests

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