False Daptomycin-Nonsusceptible MIC Results by Microscan Panel PC 29 Relative to Etest Results for Staphylococcus aureus and Enterococci

This study correlated the daptomycin MIC results obtained by Microscan and by Etest in Staphylococcus aureus and enterococci and found that the Microscan panel GP 29 had a high rate of false nonsusceptible results. Of the isolates interpreted as nonsusceptible by Microscan, 87% of Staphylococcus aureus, 90% of Enterococcus faecalis, and 88% of Enterococcus faecium isolates were interpreted as susceptible by Etest. In turn, Etest also has false nonsusceptible results compared to reference methods.