Detection ofChlamydia trachomatisin first-void urine collected from men and women attending a venereal clinic

Urethritis. Diagnosis of nongonococcal urethritis

Nongonococcal urethritis (NGU) frequently occurs in men after infection of the lower genital tract with a genital pathogen and is mostly associate with complaint of a scanty, thin discharge and urinary symptoms. Management of NGU includes clinical examination, microbiological diagnosis of genital pathogens, and efficient treatment as well as contact tracing. Diagnosis, especially of the Chlamydia trachomatis, the most frequent cause of NGU, has improved by using amplification assays for the detection of DNA or rRNA. These new methods have the advantage of a higher sensitivity especially for specimens with a low number of infectious agents. In addition, they enable the use of urine as a noninvasive specimen type.

Do men become infertile after having sexually transmitted urethritis? An epidemiologic examination

OBJECTIVE

To critically assess the possibility that gonorrhea or chlamydia causes male infertility.

DESIGN

Comprehensive literature review structured to evaluate the epidemiologic tenets for causality, including biologic plausibility, strength of association, dose response, consistency, temporality, and treatment effect.

RESULT(S)

It is biologically plausible that gonorrhea and/or chlamydia could cause male infertility. There is clinical and pathologic evidence linking these pathogens to urethritis, linking urethritis to epididymo-orchitis, and linking epididymo-orchitis to infertility. Retrospective epidemiologic results also support an association between chlamydia serologies and male infertility, which in most of these small studies does not reach the level of statistical significance. However, there is no consistent epidemiologic evidence that these pathogens alter sperm characteristics. We discuss the methodologic limitations of previous epidemiologic studies and suggest strategies for future research.

CONCLUSION(S)

Whether gonorrhea and/or chlamydia cause male infertility is currently unclear. Sound methodologic research strategies must be applied to future studies.

Detection of Chlamydia trachomatis in urethral and urine samples from symptomatic and asymptomatic male patients by the polymerase chain reaction

To evaluate the commercially available polymerase chain reaction (PCR) assay Amplicor (Roche Molecular Systems, USA) for diagnosis of Chlamydia trachomatis infection, urethral and urine swabs from a total of 344 male patients were tested and the results compared with those obtained by the nonisotopic hybridization assay Pace 2 (Gen Probe, USA) for urethral samples and by the enzyme immunoassay EIA MicroTrak (Syva, USA) for urine. Discrepant results were analyzed by a repeated test run using a major outer membrane protein-derived primer PCR, by the probe competition assay, and by the direct immunofluorescence test (DIF). Thirty-nine men (11.3%) were chlamydia positive, based on the results of all tests from both sampling sites. The rate of detection of chlamydia in urethral specimens by Amplicor and the Pace 2 was 79.5% and 61.5%, respectively, while the rate of detection in urine sediment was 75% for both Amplicor and EIA. In the first run of the PCR, a high number of false-negative results for unfrozen samples was observed, decreasing the sensitivity of Amplicor in urine to 47.3%. The results of the study indicate that Amplicor detects more infected individuals compared with other tests and is suitable as an alternative diagnostic test for chlamydia infections, using not only urethral specimens but also urine specimens. However, the finding of false-negative results when using Amplicor on unfrozen samples must be further investigated.

Comparison of DNA amplification methods for the detection of Chlamydia trachomatis in first-void urine from asymptomatic military recruits

OBJECTIVE

To evaluate the performance of DNA amplification-based tests for the diagnosis of urethral chlamydia infection from the urine of asymptomatic young men.

DESIGN

First-void urine was analyzed by two amplified DNA technologies, the ligase chain reaction (LCR), the polymerase chain reaction (PCR), and enzyme immunoassay (EIA). Specimens yielding discrepant results were subjected to retesting using either the original or a newly processed sample, and for evaluation of truly infected persons they were analyzed by the direct fluorescence antibody assay and by a second LCR directed against a segment of the gene encoding for the major outer membrane protein of Chlamydia trachomatis.

SETTING

The military hospital in which military recruits underwent medical examination before departing for a United Nations mission.

STUDY GROUP

Asymptomatic military recruits (705 young men) were screened between January and May 1994. In addition to providing urine specimens, the recruits completed questionnaires concerning previous genital infections and number of sexual partners.

RESULTS

Overall prevalence of urethral chlamydia infection in the study group was 4.1% (29/705), as determined by confirmed results in all tests collectively. The performance of the DNA amplification methods was markedly better than that of the EIA antigen detection methods. Using an expanded gold standard, the sensitivity of the LCx assay was 93.1% (27/29) compared to 62.1% (18/29) by the PCR assay Amplicor and 37.9% (11/29) by EIA. Repeat testing after freezing and thawing increased the number of positive PCR results to equal the number of positive LCR results. There were three false-positive Amplicor results and no false-positive LCR results.

CONCLUSIONS

The LCx assay performed better than the Amplicor assay and appears reliable for urine testing. The low sensitivity of the Amplicor assay requires further evaluation of possible inhibitors of PCR in fresh specimens. It was found that freezing and thawing the specimens before testing enhanced the performance of PCR.

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.

Factors affecting urine EIA sensitivity in the detection of Chlamydia trachomatis in men

OBJECTIVE

This study examined the effects of four variables on the detection of Chlamydia trachomatis in urine from men by enzyme immunoassay (EIA). These variables were: symptoms and signs of urethritis, urine polymorphonuclear leucocytes (PMN), inclusion counts from urethral chlamydia cell cultures and the time between testing and last voiding.

METHODS

Included were patients with and without symptoms and/or signs of urethritis attending the Edmonton Sexually Transmitted Disease Clinic. Men were asked to submit a 20 ml volume urine sample. Urethral swabs were collected for gram stain, chlamydia and gonorrhea culture.

RESULTS

A total of 318 men were evaluated of whom 47 had chlamydia. Excluding six men who were coinfected with gonorrhoea, sensitivities and specificities of the Microtrak, Chlamydiazyme and IDEIA systems were 78.1% and 99.6%, 75.6% and 100%, and 80.5% and 97.8% respectively. Last void time did not affect the sensitivity. However, sensitivity was best when applied to men with severe evidence of urethritis.

CONCLUSION

There is evidence that urine EIA could be used to detect chlamydia in men with acute urethritis but not in those without signs of urethritis.

Evaluation of an enzyme immunoassay for detection of Chlamydia trachomatis in urine of asymptomatic men

In a study of 1,486 men attending two sexually transmitted disease clinics, of whom 891 had no symptoms of urethritis, we compared an enzyme immunoassay (EIA) (Baxter-Bartels, formerly Northumbria AntigEnz) of urine sediment to urethral culture for the detection of Chlamydia trachomatis. C. trachomatis prevalence by culture alone was 7.7% in asymptomatic men and 10.9% in symptomatic men. Discrepant results between EIA of urine and urethral culture were evaluated by direct fluorescent-antibody staining (DFA) for elementary bodies in urine sediment or in culture transport media. When chlamydial infection was defined as either a positive urethral culture or positive EIA confirmed by DFA, chlamydia prevalence increased to 8.9% in asymptomatic men and 11.6% in symptomatic men. The urine EIA sensitivity, specificity, and positive and negative predictive values for chlamydia detection in asymptomatic men were 84.8, 99.3, 91.8, and 98.5%, respectively, with nearly identical results for symptomatic men. The sensitivities of urethral culture alone compared with the combination of urethral culture and urine EIA (with DFA confirmation) were 87.3 and 94.3% for asymptomatic and symptomatic men, respectively. The present EIA of urine sediment is both highly sensitive and specific for the detection of C. trachomatis in asymptomatic men, thus providing a noninvasive screening method for chlamydia infection in asymptomatic men attending sexually transmitted disease clinics.

Detection of Chlamydia trachomatis in the urine of young Norwegian males by enzyme immunoassay

First-void urine samples from 392 Norwegian military conscripts were investigated for the presence of Chlamydia trachomatis by enzyme immunoassay (EIA) on day 1 and day 5 after collection. Positive samples were subsequently investigated by direct immunofluorescence (IF) microscopy for the presence of chlamydial elementary bodies (EBs) in the urine pellet, and urethral swab material taken from the EIA-positive individuals was cultured. 4.8% (19/392) of the urine samples were EIA-positive on day 1, and 5.4% (21/392) were positive on day 5, with a combined total of 6.6% (26/392). Twenty-four of the 26 urine samples were confirmed as positive on IF microscopy. Urethral swabs were taken from 21 EIA-positive individuals. Six of the swabs were positive on cell culture, whereas nine were positive on IF microscopy of swab material, suggesting that these techniques perform better in symptomatic cases than in male Chlamydia trachomatis carriers. In the urine samples a notable discrepancy in EIA results was seen when the same refrigerated samples were retested on day 5 compared to day 1. This discrepancy was probably due to storage-related factors.

Evaluation of chlamydiazyme enzyme immunoassay for detection of Chlamydia trachomatis in urine specimens from men

Paired first-voided urine and urethral swab specimens were collected from 540 men attending sexually transmitted disease clinics in three geographic locations. Urine specimens were tested for the presence of Chlamydia trachomatis by commercial enzyme immunoassay (Chlamydiazyme), and the results were compared with those of urethral swab cultures. Overall prevalence of urethral C. trachomatis by culture was 14%, and the Chlamydiazyme assay had an overall sensitivity of 83%, a specificity of 96%, a positive predictive value of 76%, and a negative predictive value of 97%. Sensitivity was greater (94%) in those culture-positive samples with a high antigen load (> or = 20 inclusion-forming units per coverslip) than those with a lower antigen load (68%). Assay of urine specimens from men attending sexually transmitted disease clinics by Chlamydiazyme appears to be a reliable, noninvasive method of detection of C. trachomatis infection, and further evaluation of its performance in asymptomatic and low-prevalence populations is indicated.

Detection of Chlamydia trachomatis in urine from men with urethritis

The performance of a commercial EIA (Chlamydiazyme) for detection of Chlamydia trachomatis in urine specimens was compared with that of culture of urethral samples from men with urethritis. The incidence of chlamydial infection on the basis of culture results was 34% (56/167). The sensitivity, specificity, positive and negative predictive values for the EIA were 55% (31/56), 98% (109/111), 94% (31/33) and 81% (109/134), respectively, compared with culture. Although this EIA has a high specificity, the low sensitivity makes it valueless as a clinical tool for demonstrating chlamydial antigen in urine from men with urethritis.

Effect of time elapsed since previous voiding on the detection of Chlamydia trachomatis antigens in urine

To determine if the time elapsed since previous voiding affects the sensitivity of an enzyme immunoassay (EIA) to detect Chlamydia trachomatis in urine, 882 women and 428 men were tested for chlamydial infection in urethral specimens by isolation in cell culture (women and men) and EIA with blocking confirmation (women only). Of the 36 women (4.1%) and 38 men (8.9%) who were positive for Chlamydia trachomatis in the urethra, 55.5% (20/36) and 81.6% (31/38) respectively were positive in the first void urine (FVU) sediment by confirmed EIA. In women the sensitivity of the EIA performed on FVU was 67.8% (19/28) if the urine had been in the bladder < 3 hours and decreased to 12.5% (1/8) if longer times had elapsed (odds ratio 13.7; 95% confidence interval 1.4 to 700.0) with no obvious confounding. In men a weaker association was present (odds ratio 2.7; 95% confidence interval 0.4 to 22.3). These findings should enable investigators to optimize the analysis of urine to diagnose chlamydial infections.

Evaluation of an enzyme-linked immunoassay and confirmatory test for the detection of Chlamydia trachomatis in male urine samples

First pass urine (FPU) samples were compared with urethral swab culture from 304 males attending a genitourinary medicine clinic using an enzyme immuno assay (EIA). All of the EIA positive samples were retested by incorporating a novel blocking reagent into the EIA protocol; 101 were positive by culture of which 83 were also positive by FPU EIA, an additional four were detected in FPU only and not by culture; 86 of these 87 were also confirmed positive by the blocking reagent. Discrepant results were evaluated by Syva MicroTrak. The sensitivity and specificity of FPU EIA as compared with urethral swab culture was 82.2% (83/101) and 98% (199/203) respectively with positive and negative predictive values of 95.4% (83/87) and 91.7% (199/217). Male urethral swab culture is more sensitive than FPU EIA; however, when culture is not available then FPU offers a reliable non-invasive alternative to swab EIA which may be of enormous benefit in community screening of asymptomatic as well as symptomatic patients.

Evaluation of a chemiluminometric immunoassay for detection of Chlamydia trachomatis in the urine of male and female patients

A chemiluminometric immunoassay (Magic Lite Chlamydia) for detection of Chlamydia trachomatis antigens in first-void urine samples was compared with cell culture using urogenital swabs from 221 men and 242 women. The rate of isolation of Chlamydia trachomatis was 23.5% in men, nearly 80% of whom had symptoms of urethritis, and 8.3% in women, in whom both cervix and urethra samples were tested. In urine sediments from men and women respectively the chemiluminometric assay showed a sensitivity of 80.8% and 70%, a specificity of 97% and 95%, a positive predictive value of 89.4% and 58.3%, and a negative predictive value of 94.3% and 97.2%. Discrepancies between results obtained with the chemiluminometric assay and cell culture were resolved using two polymerase chain reaction techniques to test urogenital samples. The detection of Chlamydia trachomatis in urine samples with the chemiluminometric assay was confirmed to be superior for screening symptomatic men with urogenital infections than women as a lower prevalence population.

Detection of Chlamydia trachomatis antigens in first-void urine to identify asymptomatic male carriers

Early morning first-void urine collected from 279 sexually active Swedish male recruits (mean age 19.5 years) was tested by two commercial enzyme immunoassay (EIA) kits, MicroTrak and IDEIA III, and by MicroTrak direct fluorescence assay (DFA), to detect Chlamydia trachomatis antigens. A result was assumed to be true-positive when any of the two non-culture tests were positive for the same specimen. In one case where only DFA was positive, confirmatory chlamydial testing was performed by isolating the organism from a urethral swab. On these premises, the number of true-positive men was 26 (9.3% of all men studied). The sensitivity, specificity, positive predictive value and negative predictive value for MicroTrak EIA were 85%, 98%, 85%, and 98%, respectively. IDEIA III was less sensitive than MicroTrak EIA (42% vs 85%). In conclusion, the diagnosis of asymptomatic chlamydial infections in men can be established with reasonable accuracy by the detection of Chlamydia antigens in urine samples using MicroTrak EIA.

Chlamydial antigen detection in urine samples by immunofluorescence tests

To investigate the diagnostic value of a direct immunofluorescence test (DIF-test), urethral samples and first catch urine (FCU) from 153 male patients attending an outpatient clinic for sexually transmitted diseases (STD) were studied. Of the male patients, 40 (26.1%) had a positive urethral culture, 39 (25.5%) had a positive urethral DIF-test, and 32 (20.9%) were positive in urine according to the DIF-test. The sensitivity and the specificity of the DIF-test in male urine specimens were 75% and 98.2%, respectively, as compared with the chlamydial culture, and 69.2% and 95.6%, respectively, as compared to the DIF-test of the urethral samples. Out of the positive urethral samples, 31% had less than 5 elementary bodies (EBs) and 41% greater than 10 EBs, detected by the DIF-test. The corresponding data for FCU were 47% and 22%, indicating a smaller number of chlamydiae in urine than in urethral samples. False negative results in the urine DIF-test were mostly observed in males with a low number of EBs in the urethra. The DIF-test was less sensitive for FCU than for urethral specimens. Therefore, urine DIF-tests cannot replace conventional methods for chlamydial diagnosis in symptomatic STD patients, but may be recommended when genital sampling is not possible and may serve as an important approach in the control of genital chlamydial infections.