Objectives: To examine the accuracy of a commercial polymerase chain reaction (PCR) test (Amplicor
CTR,
Roche Diagnostic Systems, Branchburg NJ) for identification of endocervical chlamydial
infections through both laboratory evaluation and among a diverse teaching hospital patient
population.Methods: Testing of reliable threshold inocula and reproducibility were carried out using laboratory
stock organisms. Paired endocervical samples from patients with a wide range of indications
were tested by PCR and an established culture procedure, and discrepant pairs were further
analyzed to determine true results.Results: Laboratory evaluation suggested that one copy of target DNA from a viable organism
consistently yielded a positive result, and test reproducibility was very good, with an overall coefficient
of variation of 15%. Compared to true results in 1,588 paired clinical samples from 1,489
women with a 10% prevalence of infection, the PCR test and culture yielded respective sensitivities
of 87.4% and 78.0%, and negative predictive values of 98.6% and 97.6%. Specificity and positive
predictive value for both tests were 100%. Cost per specimen was nearly identical at $18.84 and
$18.88 respectively. Polymerase inhibitors and organisms lacking target DNA were not found in
false-negative PCR samples.Conclusion: This commercial PCR test is accurate, cost-competitive, and much faster than culture
for diagnosis of endocervical chlamydia infections in our population of intermediate prevalence
of chlamydial infection.
