- PYRase Test is colorimetric enzymatic test for detection of pyrrolidonyl peptidase (PYRase), an enzyme produced by all common species of Enterococci and 98% strains of S. pyogenes. It’s also used to detect PYRase activity in Citrobacter spp so it’s used to distinguish Citrobacter from Salmonella.
- PYR test uses Test Cards impregnated with L-pyroglutamic acid 7-amino-4-methyl-coumarin (7AMC) and dimethylamino-cinnamaldehyde for the detection of PYRase activity.
- The enzymatic hydrolysis of this substrate by enterococci, Group A streptococci and Citrobacter spp. produces a purple colour followed by the addition of the Developing Solution.
Test Procedure:
- Apply one suspect colony (0.5mm or larger) onto the test area (enough to make a visible smear).
- Moisten test area with 1 drop of Buffer.
- Incubate the inoculated Test Card at room temperature (15-30°C) for 5 minutes.
- Dispense 1 drop of Developing solution onto the test area. Development of a purple colour on and around the colonies within 20 seconds confirms PYRase activity.
PYR test results (Left circle shows PYR -ve, Right circle shows PYR +ve)
PYRase Positive Test – Notice Purple Color
