Table 1.

Predicted proportion of replicates that were positive versus the C. pneumoniae concentration for non-nested and nested C. pneumoniae PCR tests

ProbitaC. pneumoniae IFU/ml (95% CI)
Non-nested PCRbNested PCRc
0.010.02 (0.01, 0.03)0.01 (0.003, 0.02)
0.050.05 (0.02, 0.08)0.03 (0.01, 0.05)
0.100.08 (0.04, 0.13)0.05 (0.02, 0.08)
0.150.12 (0.07, 0.18)0.07 (0.04, 0.11)
0.200.16 (0.10, 0.24)0.09 (0.06, 0.14)
0.300.27 (0.17, 0.40)0.15 (0.10, 0.23)
0.400.41 (0.28, 0.61)0.24 (0.16, 0.35)
0.500.61 (0.42, 0.92)0.35 (0.24, 0.52)
0.600.92 (0.62, 1.42)0.53 (0.36, 0.80)
0.701.41 (0.94, 2.29)0.81 (0.55, 1.28)
0.802.34 (1.51, 4.08)1.34 (0.88, 2.23)
0.904.69 (2.82, 9.25)2.70 (1.66, 5.12)
0.958.34 (4.68, 18.4)4.79 (2.77, 10.2)
0.9924.50 (11.9, 67.8)14.1 (7.07, 37.3)
  • a Probit, predicted proportion of replicates positive from probit regression analysis (SPSS), based on 10 replicates of 16 dilutions of C. pneumoniae ATCC VR-1310 (see the text).

  • b Campbell et al. (6).

  • c Tong and Sillis (23).