Diagnosis of Chlamydia trachomatis infections in asymptomatic men and women by PCR assay

Abstract

A PCR assay was evaluated for its ability to detect genital chlamydial infection in asymptomatic men and women. Urethral swab specimens were collected from 472 men for culture and PCR assay, and first-void urine (FVU) specimens were collected from 379 of these men for enzyme immunoassay (EIA) and PCR assay. Cervical swab specimens were collected from 242 women for culture, EIA, and PCR assay. Patients were considered infected if they were culture positive or positive by PCR with both plasmid-and major outer membrane protein-based primers. By using this extended ''gold standard,'' the prevalence of infection in this population was 7.6% for men and 7.9% for women. For men, the sensitivities of urethral swab specimen culture and PCR and FVU specimen EIA and PCR were 61, 72, 55, and 91%, respectively. All assays had specificities of >99.8%. The positive and negative predictive values for PCR testing of FVU specimens were 100 and 99.4%, respectively, compared with values of 96.3 and 97.8%, respectively, for PCR of urethral swab specimens. The sensitivities of cervical swab specimen culture and PCR testing were 42 and 90%, respectively, with corresponding specificities of 100 and 99.3%. All cervical swabs were negative by EIA. Molecular techniques such as PCR assays are valuable tools for the detection of asymptomatic genital chlamydial infection. In particular, PCR assays of FVU specimens from men offer a highly sensitive, noninvasive screening tool that will likely improve patient compliance for diagnostic testing.

Detection of Chlamydia trachomatis in urine samples by nucleic acid tests: comparison with culture and enzyme immunoassay of genital swab specimens

“…More recently, the use of nucleic acid amplification tests has enabled the detection of low copy numbers (Ͻ10 pg) of specific nucleic acids in a wide variety of genital specimens, including urine, and with claims of a sensitivity greater than that of immunoassays for detecting chlamydia lipopolysaccharide or outer membrane proteins (14,22). However, the use of clinical samples may be associated with inhibition in nucleic acid amplification tests (1,10,11,14,19,23) and may lead to variable sensitivity. This study compared the use of two commercially available nucleic acid amplification tests-Amplicor PCR (Roche Diagnostics) and ligase chain reaction (LCR; Abbott Laboratories) in urine samples-with culture and EIA in cer-vical or male urethral specimens for the detection of C. trachomatis.…”

Noninvasive Screening for Genital Chlamydial Infections in Asymptomatic Men: Strategies and Costs Using a Urine PCR Assay

“…Consecutive men with no urethral symptoms presenting to the Ottawa-Carleton Sexual Health Centre, Ottawa, Ontario were asked to participate in the study as previously described (12). Of the 472 men who gave informed consent, information from the standardized questionnaire in-…”

“…The advent of nucleic acid amplification technology, such as polymerase chain reaction (PCR), ligase chain reaction (LCR) and transcription mediated amplification, has brought dramatic improvements in test performance over culture and other nonculture tests because of lower detection thresholds. Recent studies have shown that the assays can also be used on FCU from both men and women (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22). However, these nucleic acid-based assays are technically more demanding and more costly than nonculture tests such as EIA, which are currently used in most laboratories.…”

“…Laboratory tests: Two urethral swab specimens were obtained on Dacron swabs from all study participants who had not voided in the previous 2 h. The first swab specimen was placed immediately into chlamydia transport medium and stored at 4°C. Samples were processed for C trachomatis culture using Hela 229 cells and for PCR (Amplicor C trachomatis assay, Roche Diagnostics Systems, New Jersey) (12). The second specimen was obtained for a Gram-stained smear for PMNs, and for Neisseria gonorrhoeae culture as part of the clinic protocol.…”

“…After the urethral swabs were taken, FCU specimens (20 mL) were collected from a subset of men (n=379) for the LET (Boehringer Mannheim) and for PCR. Discrepant results between urethral culture and urine or urethral swab PCR were confirmed by another PCR reaction using primers for the chlamydial major outer membrane protein (12). A 1+ score for the LET and a count of four PMNs per high power field were considered positive results.…”