Presumptive identification of streptococci by pyrrolidonyl-beta-naphthylamide (PYR) test.
BACKGROUND
Group A streptococci and enterococci can be differentiated from other streptococci on the basis of their ability to cleave L-pyrrolidonyl-beta-naphthylamide.


METHODS
In the present study, the L-pyrrolidonyl-beta-naphthylamide (PYR) test, pigment medium and bile esculin medium have been used to presumptively identify the streptococci. In total, 114 strains of group A streptococci, 350 strains of non-group A streptococci, 202 strains of enterococci and 197 strains of non-enterococci have been tested.


RESULTS
The results of the present investigation show that sensitivities of different test methods are: PYR broth, 99.08%; Murex PYR, 98.48%; bacitracin, 95%; bacitracin and sulfamethoxazole/trimethoprim (SXT), 95%; pigment medium, 99.23%; bile esculin medium, 99.26%. Additionally, specificities of various tests are: PYR broth and Murex PYR, 99.82%; bacitracin, 90.90%; bacitracin and SXT, 98.87%; pigment medium and bile esculin medium, 100%, respectively.


CONCLUSIONS
PYR test has been observed to be very easy to use and may hence be considered as a rapid, reliable and cost-effective method for presumptive identification of group A streptococci and enterococci in the clinical laboratory.
Chen
C H
CH
Department of Pathology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, R.O.C.
Huang
L U
LU
Lee
J H
JH
Lee
W H
WH
D016983:Enterococcus / Q000302:isolation & purification*; D006801:Humans; D011760:Pyrrolidinones / Q000378:metabolism*; D012680:Sensitivity and Specificity; D013297:Streptococcus pyogenes / Q000302:isolation & purification*
D011760:Pyrrolidinones; C034099:pyrrolidonyl-beta-naphthylamide