Table 1.

PCR testing of endocervical specimens for C. trachomatis with the Amplicor assay: initial A450values in a series of consecutive samples and reproducibility of results according to absorbance subsets.

Test resultAbsorbanceSpecimens in consecutive series95% confidence interval, %Number of specimens tested for reproducibility1Agreement of duplicate-repeat tests with initial resultsAgreement, %
Number%
Negative<0.2447989.488.1–90.5332658 of 66499.1
Equivocal0.2–0.55921.20.8–1.779633 of 7979.7
Positive>0.5–1.0260.50.3–0.95754 of 11447.4
>1.0–1.570.10.0–0.41523 of 3076.7
>1.5–2.0150.30.1–0.63554 of 7077.1
>2.0–2.5100.20.1–0.41426 of 2892.9
>2.5–3.0130.30.1–0.52444 of 4891.7
>3.0–3.5400.80.5–1.21019 of 2095.0
>3.53627.26.2–8.384166 of 16898.8
Subtotal of positives on initial testing4739.48.5–10.4
Total5011650
  • 1 Includes specimens from both the consecutive series of 5011 specimens and from the supplemental series defined in the text.

  • 2 Of these cases, 14 were found to be positive, and 44 negative, according to the criteria of the test. One specimen was not tested further; its status was not resolved. Excluding this case, the positive rate was 487 of 5010, or 9.7% (95% confidence interval, 8.8–10.7%).

  • 3 The number of cases in which application of the manufacturer’s criteria to each of three sets of duplicate-repeat tests led to the same conclusion as to whether an initially equivocal specimen was positive or negative.