docshah
Forum Junior
Topics: 20
Posts: 56
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I was reading that S. Aureus, E. Faecalis, and S. pyogenes are PYR +'ve. This demonstrates the presence of PYRROLIDONYL ARYLAMIDASE.
What is this?? :shock:
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| mash
Forum Fanatic
Topics: 147
Posts: 1,326
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Organisms possessing the enzyme L-pyrrolidonyl arylamidase can hydrolyze the disk substrate L-pyrrolidonyl-ß-naphthylamide to release L-pyrrolidone and ß-naphthylamide. Visual detection can be achieved by the addition of PYR/LAP Reagent .the active ingredient, p-dimethylaminocinnamaldehyde, combines with the end-product ß-naphthylamide to form a red Schiff base. A positive reaction is a yellow to red color change.
PYR disks are mainly used for the presumptive identification of group A ß-hemolytic streptococci (i.e. Streptococcus pyogenes). Among the commonly encountered b-hemolytic streptococci only S. pyogenes produces a positive reaction. The accuracy and rapidity of the PYR test allows for quicker reporting of results for those cultures screened for group A streptococci and can result in better patient care and treatment.
PYR disks can also be used for the presumptive identification of Enterococcus species. The most accurate presumptive identification of a catalase-negative gram-positive coccus as an Enterococcus strain is by demonstrating that the unknown strain is PYR and LAP positive and grows in 6.5% NaCl, and at 45°C.
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| Sakaki-
Forum Senior
Topics: 1
Posts: 238
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As mash described, a pink or red colour upon addition of p-dimethylaminocinnamaldehyde indicates positivity in the PYR test, and it can be used in the presumptive identification of Enterococcus (distinguishing from gamma-hemolytic streptococci) or Strep pyogenes (distinguishing from beta-hemolytic streptococci - mainly Strep agalactiae).
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| docshah
Forum Junior
Topics: 20
Posts: 56
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Your awesome!!
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