TABLE 2.

Calibration curve equations and performance characteristics of qPCR assays

AssayDNA typeaCalibration equationAmplification efficiencycROQ (copies) for target DNA%CV across ROQMethodd
CowM2Plasmidy = −3.58x + 41.2b1.9025-2.5 × 1062.08Multiplex
CowM3Plasmidy = −3.67x + 42.6b1.8725-2.5 × 1061.18Simplex
BthetaGenomicy = −3.43x + 39.11.96100-4 × 1040.63Multiplex
GB342Genomicy = −3.27x + 38.82.02100-4 × 1041.11Multiplex
Entero1Genomicy = −3.53x + 38.21.92100-4 × 1041.57Multiplex
  • a DNA standards from which the calibration equation was generated (Fig. 2).

  • b The calibration equation was adjusted based on posterior mean differences in slope and intercept between genomic and plasmid DNA-generated standard curves from Btheta, GB342, and Entero1 assays.

  • c Amplification efficiency = 10(1/−slope).

  • d Either a simple approach or multiplex strategy where the target DNA was simultaneously detected with an IAC.