Ligase Chain Reaction Testing Research Articles

Detection of Chlamydia trachomatis by ligase chain reaction compared with polymerase chain reaction and cell culture in urogenital specimens.

The aim of this study was to evaluate the newly developed ligase chain reaction (LCR) assay for the detection of Chlamydia trachomatis in urogenital specimens using cell culture and Amplicor PCR for comparison. Two hundred and eighty patients attending hospital or urban STD clinics (high-risk population, 62 men and 84 women) and obstetric/gynaecology clinics (low-risk population, 134 women) in Bordeaux, France. Specimens from men were tested with LCR on urethral swabs and urine, with Amplicor or urine, with cell culture on urethral swabs. Specimens from women were tested with LCR, Amplicor and cell culture on endocervical swabs and with LCR on urine. When the three methods generated different results, the LCR and Amplicor tests were repeated on the remaining samples. Samples with discordant LCR and Amplicor results and a negative culture were further analysed by major outer membrane protein gene omp1-PCR. After analysis of discrepant results, the overall prevalence was 7.5% (21/280) calculated on the basis of an expanded "gold standard" defined as culture positive or LCR plus Amplicor positive or omp1-PCR positive for discrepant results between LCR and Amplicor tests. Of the 21, 20 were detected by LCR, 17 by Amplicor and culture. The specificity of LCR and Amplicor was 99.6%. The LCR Chlamydia trachomatis test is a highly sensitive nonculture technique and a good alternative test for the detection of chlamydial infections.

Diagnosis Of Chlamydia Trachomatis Urethral Infection In Symptomatic And Asymptomatic Men By Testing First-Void Urine In A Ligase Chain Reaction Assay

A multicenter study compared ligase chain reaction (LCR) of Chlamydia trachomatis plasmid DNA with culture of urethral swab specimens from 542 men (study A); a second study (B) compared LCR of first-void urine (FVU) with urethral swab cultures from 1043 men. Discordant results were resolved with direct fluorescent antibody staining of sediments from the FVU or urethral culture specimen and with a second LCR directed against a fragment of the major outer membrane protein gene. Test performance was calculated on the basis of an expanded reference standard. The LCR plasmid assay had a sensitivity of 98.0% in study A and 93.5% in study B; specificity was 99.8%-100%. The sensitivity of culturing urethral swabs from all study sites was 68.2% (range by sites, 40.0%-84.6%). The presence or absence of urethral symptoms did not alter the results. Use of this LCR test should allow more meaningful investigation and treatment of C. trachomatis infections in men.

Diagnosis of Chlamydia trachomatis infections in men and women by testing first-void urine by ligase chain reaction

From April to September 1993, 305 men and 447 women in Hamilton, Canada, consented to the collection of a urethral or cervical swab, respectively, for culture and 20 ml of first-void urine (FVU) for testing by the enzyme immunoassay Chlamydiazyme and by ligase chain reaction (LCR) in the form of a kit from Abbott Laboratories called LCx Chlamydia trachomatis. Evaluation of test performance with each specimen was calculated on the basis of an expanded "gold standard" of a patient found to be positive by culture or by a confirmed nonculture test. By using this expanded standard, the prevalence of infection was determined to be 6% (27/447) for the women and 18.4% (56/305) for the men. LCR testing of FVU in both studies was the most sensitive approach (96%). The performance of Chlamydiazyme was as follows: cervical swab, 78.3% sensitivity; female FVU, 37% sensitivity; and male FVU, 67.9% sensitivity. Culture was the least sensitive approach to diagnosis: female cervix, 55.6%; and male urethra, 37.5%. LCR testing of FVU from men or women diagnosed the greatest number of genitourinary tract infections with no false positives.