Ligase chain reaction to detect Chlamydia trachomatis infection of the cervix

We performed a multicenter evaluation of ligase chain reaction (LCR) in the diagnosis of Chlamydia trachomatis infection of the cervix. This LCR provides an amplification of target sequences within the chlamydial cryptic plasmid. The LCR results were compared with those of isolation in cell culture. Discrepant (tissue culture-negative and LCR-positive) test results were resolved by the application of a direct immunofluorescent-antibody test to detect chlamydial elementary bodies and by the use of alternate DNA primers that targeted the chlamydial major outer membrane protein gene. A total of 234 of 2,132 specimens (10.9%) could be confirmed as containing C. trachomatis. Of these, 152 were detected by isolation in cell culture and 221 were detected by LCR. The corresponding sensitivities were 94% for LCR and 65% for cell culture. There was greater variability among study site results for cell culture sensitivity (52 to 92%) than for LCR sensitivity (87 to 98%). The specificity of each test was greater than 99.9%. Thus, LCR offers a highly sensitive nonculture method for detecting chlamydial infection of the cervix.