Ceftaroline MIC results from multiple methods and testing sites were within +/− 1 two-fold dilution for average of 99% of results.

Category agreement to reference BMD for all methods ranged from 85.7–93.2%.

Categorical errors were attributed solely to S. aureus isolates with MIC results of 1 and 2 mg/L, which are categorized as either susceptible or resistant by EUCAST breakpoints and include both MRSA “wild type” PB2a and nPBD PBP2a substitutions.

The introduction of an intermediate interpretive category would assist the laboratory with correct interpretation of borderline susceptible/resistant isolates.