Summary of the clinical performance of Portrait Staph ID/R BCP versus cefoxitin disk diffusion test method for the detection of methicillin resistance in 762 prospective blood culturesa

Result, all sites combined, for detection of methicillin resistance% Agreement
TP/TP + FNPPA (95% CI)TN/TN + FPNPA (95% CI)
S. aureus72/7596.0 (86.6–97.8)682/68799.3 (98.3–99.7)
S. lugdunensis0/0NA762/762100 (99.5–100)
Staphylococcus spp. other than S. aureus or S. lugdunensis247/26393.9 (90.3–96.2)481/49996.4 (94.4–97.7)
  • a Three culture isolates of Staphylococcus failed to grow on Mueller-Hinton agar for cefoxitin testing. TP, true positive; TN, true negative; FP, false positive; FN, false negative; PPA, positive percent agreement; NPA, negative percent agreement; CI, confidence interval. NA, not applicable.