Evaluation of the BD Phoenix SMIC/ID, a new streptococci identification and antimicrobial susceptibility panel, for potential routine use in a university-based clinical microbiology laboratory

We evaluated the new BD Phoenix automated microbiology system (Becton Dickinson Diagnostic Systems, Sparks, MD) SMIC/ID-4 panel for routine identification (ID) and antimicrobial susceptibility testing (AST) of streptococci in a university-based laboratory. Clinical isolates of Streptococcus pneumoniae (n = 92), Streptococcus pyogenes (n = 24), and Streptococcus agalactiae (n = 10) were collected, and comparisons were made with the routine manual methods used in our microbiology laboratory for ID and susceptibility testing. ID concordance with manual methods was 85.9%, 95.8%, and 90.0% for S. pneumoniae, S. pyogenes, and S. agalactiae, respectively. With respect to AST concordance for S. pneumoniae and β-hemolytic streptococci (S. pyogenes and S. agalactiae) using Phoenix and standard broth microdilution panels, overall essential agreement was 93.0% and 97.5%, respectively, whereas overall category agreement was 92.4% and 98.9%, respectively. Major and minor error rates for S. pneumoniae and β-hemolytic streptococci were 0.5% and 0.3%, and 7.1% and 0.8%, respectively. Very major errors were not observed in this study. Mean time for ID and AST test completion was 13.6 ± 1.6, 10.7 ± 2.4, and 11.2 ± 2.3 h for S. pneumoniae, S. pyogenes, and S. agalactiae, respectively. We have demonstrated that Phoenix ID results show high agreement with manual ID and that AST performance was equivalent to standard broth microdilution in less time.