DETECTION OF CHLAMYDIA-TRACHOMATIS IN A LOW-PREVALENCE FEMALE-POPULATION USING ROCHE AMPLICOR PCR, PHARMACIA EIA AND TISSUE-CULTURE

Amplicor PCR (Roche Diagnostic Systems, Frenchs Forest, Australia) was compared with Phadebact EIA (Boule Diagnostics, Huddinge, Sweden) and tissue culture for the detection of C. trachomatis from endocervical swabs in a low prevalence patient population of 1,002 women. Incomplet e sets of samples were collected from ten patients. Of the remaining 9 92, 22 gave a positive result by at least one of the test methodologie s; 17 by culture, 18 by PCR and 14 by EIA. To resolve discrepant resul ts, specimens were subjected to additional testing; PCR on culture, di rect fluorescence on the deposit of the EIA and culture specimens and testing by a different PCR with primers directed against the major out er membrane protein (MOMP) of C. trachomatis. To further reduce result bias, 25% of all negatives were selected at random for testing by PCR directed against MOMP. All gave negative results. A resolved positive result was defined as being positive by culture or by any two alterna tive methods. The sensitivity, specificity and positive predictive val ue (PPV) before resolution of positive results was 76.5%, 99.9% and 92 .9% for EIA and 76.5%, 99.5% and 72.7% for PCR. After resolution of po sitive results, the sensitivity, specificity and PPV values was 66.7%, 100%, and 100% for EIA, 81%, 99.9%, and 94.4% for PCR and 81%, 100% a nd 100% for culture. These results indicate that Roche Amplicor PCR an d culture perform similarly, while Pharmacia EIA is considerably less sensitive than either in a low prevalence female population.