From the Department of Microbiology, Pasteur Institute of Iran, Pasteur Avenue, Tehran
Abstract: (3838 Views)
In a clinical trial a new pyrrolidonyl-β-naphthylamide (PYR) hydrolysis test
was compared with the bacitracin disk susceptibility test for accuracy in the
presumptive identification of group A streptococci (GAS). Among 128 isolates of
beta-hemolytic streptococci 93 group A isolates were found. The sensitivity of the
PYR and bacitracin tests were similar (98.9%), but the bacitracin test had a lower
specificity (80%) than the PYR test (100%). The efficiency of the PYR and
bacitracin test were 99.2% and 93.7%, respectively. All bacitracin tests were
performed on subcultures of the isolates from the primary plate, whereas PYR
testing was performed on colonies from the primary plate. This shortened the
turnaround time for the PYR test compared to the bacitracin test by at least 24
hours.