Optimal method of collection of first-void urine for diagnosis of Chlamydia trachomatis infection in men.

First-void urine (FVU) is the preferred specimen for the diagnosis of urogenital Chlamydia trachomatis infection in men. We have developed FirstBurst, a urine collection device that collects the first 4 to 5 ml of FVU and yields a specimen with a sixfold higher C. trachomatis organism load than the regular urine cup by quantitative PCR (32,533 versus 5,271 plasmids/ml; P < 0.0001). Consequently, the use of FirstBurst to collect a urine sample improved the sensitivity of a rapid test for Chlamydia over testing of samples collected with a urine cup (82 versus 47% sensitivity using PCR as a reference; P < 0.0015).

Prevalence of Chlamydia trachomatis infection among low- and high-risk Filipino women and performance of Chlamydia rapid tests in resource-limited settings.

The prevalence of urogenital Chlamydia trachomatis infection was determined with a PCR-based test of women from low- and high-risk populations in Iloilo City, Philippines, between August 2002 and March 2006. Two rapid tests for C. trachomatis, Clearview Chlamydia MF and the Chlamydia Rapid Test (CRT), were also evaluated in these resource-limited settings. Specimens were obtained from female sex workers (FSWs; n = 1,484) attending a social hygiene clinic (SHC) and from women (n = 838) attending an obstetrics-gynecology (OB-GYN) clinic. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the rapid tests were determined, with PCR as the gold standard. The PCR positivity rate for SHC participants (72% asymptomatic) ranged from 17.9 to 32.0% during the study period. Compared with those of PCR, the sensitivities and specificities of the Clearview test were 53.5 and 99.1%, respectively, with endocervical swab specimens (CS; n = 822) from the FSWs and 31.1 and 95.2%, respectively, with vaginal swab specimens (VS; n = 333) from these women. The sensitivity, specificity, PPV, and NPV of the CRT with VS from the FSWs were 71.0, 99.0, 97.1, and 87.9%, respectively. At the OB-GYN site, the PCR positivity rate with VS was 6.3%. The sensitivity, specificity, PPV, and NPV of the CRT with these specimens were 86.8, 99.6, 93.9, and 99.1%, respectively. The performance of the Clearview test at the SHC was thus markedly lower with VS than with CS, whereas the CRT performed well with VS from both populations.

Chlamydia trachomatis variant not detected by plasmid based nucleic acid amplification tests: molecular characterisation and failure of single dose azithromycin.

OBJECTIVE: To characterise a Chlamydia trachomatis variant strain from a patient with non-gonococcal urethritis (NGU) whose first void urine (FVU) displayed discrepant Ctrachomatis test results and describe the clinical response to treatment. METHODS: The FVU specimen was assayed with an immune based Chlamydia Rapid Test (CRT) and various nucleic acid amplification tests (NAATs) to establish C trachomatis infection. Sequencing of the major outer membrane protein gene (omp1 also known as ompA) was undertaken to identify the serovar of the variant strain. Polymerase chain reaction (PCR) analysis was also conducted to determine whether the strain harboured deletions in the cryptic plasmid or was plasmid free. RESULTS: The FVU specimen was strongly reactive in CRT but negative with the plasmid based Amplicor PCR (Roche) and ProbeTec ET (Becton-Dickinson) assays. However, NAATs for 16S RNA (Aptima Combo 2, GenProbe), omp1 (RealArt CT PCR, Artus and in-house NAATs) or the outer membrane complex B protein gene (omcB) established C trachomatis infection. Sequencing of omp1 showed that the variant belonged to serovar I. PCR analysis indicated that the variant was plasmid free. The patient did not respond to single dose azithromycin treatment but subsequently responded to a course of doxycycline. CONCLUSIONS: A pathogenic plasmid free C trachomatis variant was identified. Clinicians should be alerted to the possibility of undetected C trachomatis infection caused by such variants and the potential of azithromycin failure in patients with recurrent chlamydial NGU. The occurrence of this variant is rare and should not form the basis for judgment of the performance or usefulness of plasmid based NAATs for C trachomatis detection.

Chlamydia trachomatis load at matched anatomic sites: implications for screening strategies.

Urethral and endocervical swabs and self-collected vaginal swabs (SCVSs) and urine specimens are all used as samples for diagnosis of urogenital infection with Chlamydia trachomatis. We have now determined chlamydial organism load in matched specimens from different anatomic sites and examined its relation to clinical signs and symptoms in men and women. Organism load was measured with assays based on the ligase chain reaction or real-time PCR analysis. The mean organism loads in 58 infected men were 1,200 and 821 elementary bodies (EBs) per 100 microl of sample for first-void urine (FVU) and urethral swabs, respectively (P>0.05). Organism load in FVU samples or urethral swabs was positively associated with symptoms (P<0.01) and clinical signs (P<0.01) in men. The mean organism loads in 73 infected women were 2,231, 773, 162, and 47 EBs/100 microl for endocervical swabs, SCVSs, urethral swabs, and FVU samples, respectively (P<0.001 for each comparison). Only the presence of multiple symptoms or clinical signs was associated with organism load in women. These results show that FVU is a suitable noninvasive sample type for men, given the fact that its chlamydial load did not differ significantly from that of urethral swabs. Given their higher organism load compared with FVU, SCVSs are the preferred noninvasive sample type for women.