Figure 4. Determination of cutoff values of the signal indices of PCR analysis based on bacterial bioburden determined by culture. The cutoff values corresponding to the predetermined bacterial bioburden, 200 colony-forming units (CFU)/ml (A), 2,000 CFU/ml (B), and 12,000 CFU/ml (C) of bacteria, were determined with receiver operating characteristic plots. The performances of the cutoff values of PCR indices are summarized in the inserted table. AUC=area under curve. C.I.=confidence interval.