Performance of Etest for Antimicrobial Susceptibility Testing of Abiotrophia defectiva and Granulicatella Species

The Etest on chocolate Mueller-Hinton agar was compared to broth microdilution (BMD) for 125 isolates of nutritionally variant streptococci. Vancomycin Etests yielded 31.1% essential agreement (EA) and 20.0% categorical agreement (CA). Penicillin Etests yielded 86.0% EA and 85.6% CA, whereas ceftriaxone Etests yielded 73.6% EA and 68.0% CA.