DETECTION OF CHLAMYDIA-TRACHOMATIS BY A LIGASE CHAIN-REACTION AMPLIFICATION METHOD

Background and Objectives: The ligase chain reaction is an in vitro DN A amplification technique that exponentially amplifies selected DNA se quences. Goal: To evaluate a ligase chain reaction assay for the detec tion of Chlamydia trachomatis cryptic plasmid DNA (LCx Chlamydia) in p atients routinely attending a sexually transmitted disease center in I taly. Study Design: Urethral or cervical swabs were obtained from 501 consecutive patients (334 men and 167 women). The samples were assayed in parallel with LCx Chlamydia and conventional tissue culture; disco rdant results were further assayed by direct immunofluorescence and a ligase chain reaction with alternate primers. Results: After resolutio n of discordant results, the LCx method showed a sensitivity, specific ity, positive predictive value, and negative predictive value of 100%, 99.3%, 96.7%, and 100% in men; 100%, 100%, 100%, and 100% in women; a nd 100%, 99.5%, 97.1%, and 100% overall, respectively. By comparison, the sensitivity of tissue culture was 81.4% in men, 50% in women, and 77.6% overall, Conclusions: The automated LCx method is sensitive, fas t, and accurate and represents a useful diagnostic tool for C. trachom atis infection, even in low and medium prevalence populations.