Value of the L-pyrrolidonyl-beta-naphthylamide hydrolysis test for identification of select gram-positive cocci

A 4 hr test for hydrolysis of L-pyrrolidonyl-beta-naphthylamide (PYR) was evaluated for its use in identifying group A beta-hemolytic streptococci, group D enterococci, and Staphylococcus haemolyticus. All of the group A streptococci and the enterococci tested were positive in the PYR test, whereas all of the nongroup A, B, or D beta-hemolytic streptococci, all of the viridans, and all of the Streptococcus pneumoniae isolates tested were PYR negative. Two strains of Aerococcus species were PYR positive and could not be differentiated from enterococci in this test. All strains of S. haemolyticus, a single strain of S. intermedius and two of seven strains of S. warneri were PYR positive whereas all other staphylococci tested were PYR negative. The PYR test is suitable for routine, presumptive identification of group A streptococci, group D enterococci and S. haemolyticus in the clinical laboratory.