Non-invasive sampling method for detecting Chlamydia trachomatis

Chlamydial infection in asymptomatic infertile men attending an andrology clinic

Urethral swabs, first-catch urine or urine collected at least 2 h after the previous micturition, and semen swabs were collected from 131 asymptomatic men during the routine workup for infertility at the andrology clinic at Ga-Rankuwa Hospital, Medunsa. The urethral and seminal swabs were used for enzyme immunoassay (EIA) (IDEIA III), tissue culture, and direct immunofluorescent antibody (DFA) test (IMAGEN) to detect Chlamydia trachomatis, and similarly the urine was tested by EIA. In 82/131 (62.6%) cases all tests for chlamydiae were negative and in 49/131 (37.4%) cases at least one test was positive. Tissue culture detected 24/131 (18.3%) as positive for C. trachomatis. Urethral swab EIA detected 33/131 (25.2%) and DFA 34/131 (26%) positive patients. Urine EIA was positive in 33/131 cases (25.2%). Semen EIA was positive in 35/131 (26.7%) of cases of whom 7/131 (5.3%) were positive in semen EIA only (all samples were conformed by PCR). It would seem, therefore, that testing for the presence of chlamydia was incomplete if semen samples were not included. The positivity in only semen samples raises the possibility that the organisms are harbored in the epididymis, seminal vesicles, or the prostate.

First-void urine testing for Chlamydia trachomatis by polymerase chain reaction in asymptomatic women

BACKGROUND

Because Chlamydia trachomatis infections are usually asymptomatic or minimally symptomatic, diagnosis is often delayed.

GOAL

To perform a comparative study of first-void urine (FVU) polymerase chain reaction (PCR) testing and endocervical swab antigen testing in the diagnosis of C. trachomatis infection among asymptomatic women.

STUDY DESIGN

The study population consisted of 1,090 unselected women attending a family planning clinic or a university student health clinic. Calculations of test performances were based on an expanded reference standard including enzyme immunoassay (EIA) or PCR tests confirmed by direct fluorescence antibody (DFA) test or major outer membrane protein PCR test, respectively.

RESULTS

The overall prevalence of C. trachomatis infection was 5.6%. After resolution of discrepant specimens, FVU PCR detected 85% (52/61) and endocervical swab EIA/DFA 90% (55/61) of confirmed positive cases.

CONCLUSIONS

These results indicate that the FVU PCR test is an accurate, noninvasive screening method and can replace endocervical swab EIA in the detection of C. trachomatis infection in low-prevalence populations.

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

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 > or = 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 symptomatic 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.

Duplex PCR system for simultaneous detection of Neisseria gonorrhoeae and Chlamydia trachomatis in clinical specimens

AIMS

To evaluate the use of a duplex polymerase chain reaction (PCR) assay for the simultaneous detection of Neisseria gonorrhoeae and Chlamydia trachomatis in clinical samples.

METHODS

Genital swab specimens were obtained from both China (203 swabs) and Hong Kong (202 swabs). N gonorrhoeae and C trachomatis were detected in each specimen with a number of tests including enzyme immunoassays (IDEIA) and PCR assays using both single and double primer pairs. The primer pair for N gonorrhoeae was derived from the cppB gene on its cryptic plasmid and the PCR product was 390 base pairs long. For C trachomatis, the PCR product was 473 base pairs long, resulting from amplification of a sequence in the common 7.4 kilobase plasmid present in all serovars. For N gonorrhoeae, PCR results were also compared with those obtained by culture and Gram's smear of the discharges.

RESULTS

For the 203 specimens collected in China, similar numbers of positive results (177) were obtained by both Gonozyme and duplex PCR for the detection of N gonorrhoeae. No discrepant results were found among the cultured specimens when Gonozyme and duplex PCR were compared. C trachomatis was detected in 47 specimens by duplex PCR, but was detected in only 28 by IDEIA. Of the 202 Hong Kong specimens, 46 were positive for N gonorrhoeae, detected by both Gonozyme and duplex PCR; 34 were positive for C trachomatis, 25 of which were detected by IDEIA and the remainder by duplex PCR.

CONCLUSIONS

The duplex PCR assay is a satisfactory diagnostic tool for the simultaneous detection of N gonorrhoeae and C trachomatis in clinical swab samples. Further evaluation is suggested.

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.

Diagnosis of genital Chlamydia trachomatis infections in asymptomatic males by testing urine by PCR

An enzyme-linked immunosorbent assay (EIA) (MikroTrak; Syva) was compared with PCR (Amplicor; Roche) for detection of Chlamydia trachomatis in first-void urine (FVU) from 184 men attending a skin and venereal disease clinic. The prevalence of C. trachomatis in the population studied was 18.5%. Discrepant results between Syva EIA and Roche PCR were retested by using major outer membrane protein primer-based PCR. After retesting, the sensitivity, the specificity, and the positive and negative predictive values for the Syva EIA were 85.3, 100, 100, and 77.5%, respectively, and those for the Roche PCR 100, 100, 100, and 100%, respectively. It was concluded that PCR provides a highly sensitive and specific noninvasive screening method for genital chlamydial infection in asymptomatic men.

Urine as an alternative to urethral swabs for the diagnosis of Chlamydia trachomatis in infertile males

Swabbing the urethrae of men has been the traditional approach for collecting specimens for detection of Chlamydia trachomatis. Recently, however, urine testing using enzyme immunoassay has yielded promising results. A total of 105 patients attending the Andrology Clinic at Ga Rankuwa Hospital, Medunsa were included in the study. These patients were asymptomatic and had no urethral discharge. Three endo-urethral swabs and first-catch urine were collected from each patient. The urethral swabs were used for enzyme immunoassay (EIA) (IDEIA III), tissue culture and direct immunofluorescent antibody (DFA) test (IMAGEN) to detect C. trachomatis. In addition about 15-30 ml of first-catch urine, or urine collected at least 2h after the previous micturition, was collected for each patient for EIA testing. Fifteen (14.3%) of 105 patients were positive on urethral swab EIA, in comparison with the DFA test in which 14 (13.3%) were positive. Eight (7.8%) were positive in tissue culture. Urine EIA was positive in 17 (16.2%) patients, of whom five (4.8%) were positive in urine EIA only. All EIA positive urines were confirmed by DFA. We recommend that first-catch urine or urine collected at least 2h after the previous micturition in infertile males may be considered a suitable alternative to urethral swab for chlamydial diagnosis because it is noninvasive and nontraumatic.

Diagnosis of Chlamydia trachomatis urethritis in men by polymerase chain reaction assay of first-catch urine

To determine the accuracy of a recently developed polymerase chain reaction (PCR) urine assay to detect Chlamydia trachomatis urethral infection in men, we obtained urethral swabs and first-catch urine from 365 men attending a sexually transmitted diseases clinic. Thirty-three (9%) of the 365 men were infected with C. trachomatis as defined by urethral culture. Thirty-two of the 33 men with culture-positive urethral swabs also had PCR-positive urine assays. Of 332 patients with culture-negative urethral swabs, 325 had PCR-negative urine. Compared with chlamydia culture of urethral specimens, PCR assay of urine samples thus had a sensitivity of 97% and a specificity of 98%. The positive predictive value of the urine PCR assay was 82%, and the negative predictive value was 99%. Analysis of discrepant results indicated that six of seven PCR-positive, urethral culture-negative patients probably had chlamydial urethritis. All six patients had symptoms of urethritis and had either a positive urethral swab PCR or a positive urine PCR with a different amplification target. After resolution of discrepant results, (defining true positives as the 33 culture-positive patients and the 6 PCR-positive, culture-negative patients just described), the sensitivity and specificity of culture were 85% (33 of 39) and 100% (326 of 326), respectively. The revised sensitivity and specificity of PCR were 97% (38 of 39) and 99.7% (325 of 326), respectively. We conclude that this urine PCR assay provides a highly sensitive, noninvasive alternative method for the detection of C. trachomatis urethral infection in high-risk men attending a sexually transmitted diseases clinic. This assay could greatly facilitate the testing of larger numbers of male patients for chlamydial infection and should be studied in other settings.

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.

Confirmatory polymerase chain reaction testing for Chlamydia trachomatis in first-void urine from asymptomatic and symptomatic men

First-void urine specimens from 683 men (592 without symptoms) were tested for Chlamydia trachomatis by a polymerase chain reaction (PCR) with KL1 and KL2 plasmid primers and by a Chlamydiazyme enzyme immunoassay (EIA). Thirty-seven specimens were confirmed to be positive by using the EIA blocking reagent and a second set of plasmid primers (T1 and T2). By comparing unconfirmed PCR results (KL1 and KL2 primers only) with the blocked Chlamydiazyme EIA results, the sensitivity and specificity of PCR were 100% (37 of 37 specimens) and 99.5% (643 of 646 specimens), respectively. Three additional specimens were negative by EIA but positive by PCR and were confirmed to be positive with primers T1 and T2. Two of the three specimens were from men with symptoms. The confirmatory PCR assay performed equally well in detecting positive specimens from symptomatic (31 of 31) and asymptomatic (9 of 9) men. Comparison of confirmatory testing of first-void urine specimens by PCR and EIA showed that PCR was 100% sensitive (40 of 40 specimens) and that the EIA was 92.5% sensitive (37 of 40 specimens) but that the assays were equally specific (100%).

The laboratory diagnosis of male Chlamydia trachomatis infections--a time for change?

We carried out a two-phased study comparing the effectiveness of first-catch early morning urine (FCU) samples against urethral swabs for the detection of C. trachomatis in men. Four hundred and seventeen new and re-booked consecutive men, who attended the Department of Genito-Urinary Medicine, Bristol, having held their urine overnight, were recruited. Patients who had received antimicrobial chemotherapy in the preceding 2 months were excluded. Early morning FCU samples were obtained from 208 men followed by urethral swabs for the detection of C. trachomatis (phase I) and this order of collection was reversed for the remaining 209 patients (phase 2). A last-catch urine (LCU) was also obtained from all patients. All urethral and urine samples were examined by an amplified enzyme immunoassay (IDEIA, Dako Diagnostics Ltd). Initially, discordant samples were critically examined by direct immunofluorescence (Syva, 'Microtrak') which was used as the 'gold' standard in this study. We have shown that overall 42 and 4.7% of our symptomatic and asymptomatic male patients respectively were positive for C. trachomatis antigen by IDEIA. Furthermore 86.4 and 91.0% (phases 1 and 2) of the total C. trachomatis positive samples were detected by examination of an FCU sample. In contrast only 66.0 and 65.5% (phases 1 and 2) of the total positives were identified by examination of an urethral swab. These results show that an FCU sample not only has the advantage of being a non-invasive procedure but is also a very sensitive method, compared to swabbing the urethra for the detection of C. trachomatis.(ABSTRACT TRUNCATED AT 250 WORDS)

Demonstration of Chlamydia trachomatis in colposcopic cervical biopsy specimens by an immunoperoxidase method

A total of 31 cervical biopsy specimens were taken from 29 women attending a genitourinary medicine clinic, nine women (11 biopsy specimens) were known to have Chlamydia trachomatis cervicitis and 20 women were known to be free of chlamydial infection. The specimens were routinely processed to paraffin wax and stained by an anti-Chlamydia immunoperoxidase technique to localise the organisms. Of the 11 positive biopsy specimens three showed positive staining of elementary/reticulate bodies. In one case the surface endocervical cells showed large inclusions which were packed with chlamydial bodies. The diagnosis of chlamydial infection is difficult to make clinically and in routine cytological and histological specimens but immunoperoxidase staining can clearly identify C trachomatis inclusions in cervical biopsy specimens provided infection is severe.

Evaluation of an enzyme immunoassay (Chlamydiazyme) with confirmatory test for the detection of chlamydial antigen in urine from men

First catch urine specimens from 312 male patients were examined for the presence of chlamydial antigen by an enzyme immunoassay (Chlamydiazyme). Positive results were repeated and confirmed using a blocking assay. In addition, urethral swabs were examined by cell culture for Chlamydia trachomatis. Discrepant results were further analysed by direct immunofluorescence (IF) of the spun urine deposit. Paired specimens were positive from 26 subjects, and negative from 276 subjects. Eight paired specimens were urethral culture positive, and urine EIA negative. Two specimens, urine EIA positive but urethral culture negative, were positive on direct IF. The sensitivity, specificity, predictive value of a positive result, and predictive value of a negative result for urine EIA against cell culture and/or direct IF were 77.8%, 100%, 100% and 97.2% respectively.

Chlamydia trachomatis antigen can be detected in the urine sample of men with non-gonococcal urethritis

We tested the first portion of voided urine (FVU) and urethral swab from 80 patients with non-gonococcal urethritis (NGU) using a novel enzyme-amplified immunoassay (IDEIA) for the detection of Chlamydia trachomatis antigen. Urine specimens were positive in all patients with positive urethral swabs (positive coincidence ratio, 100%) and in 6 of 54 patients with negative swabs (negative coincidence ratio, 88.9%). Our data suggest that FVU is suitable for the detection of Chlamydia trachomatis antigen using the IDEIA test in patients with NGU.

Laboratory techniques for the diagnosis of chlamydial infections

Yolk-sac inoculation of embryonated eggs was superseded 25 years ago by the use of cell cultures (often McCoy) for the isolation of Chlamydia trachomatis. Centrifugation of specimens onto the cell monolayers was shown to increase sensitivity, but little of late has further improved sensitivity which is at least ten-fold greater than that of eggs. However, culture is slow and labour intensive so that non-cultural techniques without these drawbacks have come to dominate. Direct fluorescent antibody (DFA) tests are rapid and have sensitivities that range from 70% to 100% for men and 68% to 100% for women, and specificities that range from 87% to 99% for men and 82% to 100% for women; if the tests are read by competent observers the values are at the top end of the ranges. The detection rate may be enhanced even further by relatively low-speed centrifugation of specimens before staining. Skilled reading is not a feature of enzyme immunoassays (EIAs) which according to the literature have sensitivities that range from 62% to 97% for men and 64% to 100% for women, and specificities that range from 92% to 100% for men and 89% to 100% for women. However, comparison against poor reference tests is responsible for most of the higher values and the clinician should not be misled into believing that EIAs have excellent sensitivity; the lower values in the ranges are closer to reality. Furthermore, EIAs that are being designed for use by general practitioners should be regarded with the greatest caution since lack of sensitivity means that chlamydia-positive patients will go undetected. The polymerase chain reaction (PCR) is not bedevilled by insensitivity but it is no more sensitive than the most sensitive cell culture or DFA tests. PCR is unsuitable for routine diagnosis but has a place as a research tool. For men, examination of "first-catch" urine samples by the best of the non-cultural procedures provides an acceptable non-invasive approach to diagnosis; for women, the value of examining urine may be less, but needs to be thoroughly tested. However, there is little doubt that a Cytobrush used to obtain cervical specimens holds no practical advantage over a swab. Serological tests are reliant on the provision of paired sera for making a diagnosis; high antibody titres in single sera may be suggestive of an aetiological association in deep-seated chlamydial infections (epididymitis, arthritis, salpingitis, etc), but unequivocal interpretation is unusual, particularly in an individual case, since the distinction between a current and past infection is problematical.

Simplification of procedures used to test urine samples for Chlamydia trachomatis

Two methods of simplifying the procedure for examining urine samples for Chlamydia trachomatis were investigated. When 73 urine samples from 56 men with acute non-gonococcal urethritis were examined by direct immunofluorescence (MicroTrak), centrifuging 1 ml volumes of urine at 13,000 rpm for five minutes was at least as efficient for detecting C trachomatis as centrifuging larger volumes at 3000 rpm for 30 minutes. Furthermore, examination of urine produced during a visit to a sexually transmitted disease clinic was at least as efficient as examination of early morning urine for detecting C trachomatis by MicroTrak, or by an enzyme immunoassay (IDEIA). Both modifications have practical advantages and should encourage the use of urine samples for diagnosing chlamydial infections in men.

Detection of Chlamydia trachomatis in urinary samples from women

With a mean age of 21 years 197 women at risk for an infection with Chlamydia trachomatis (CT) had a urinary sample (20 ml first-void urine, minimum 4 hours from prior mictuation) analysed with an enzyme immunoassay (IDEIA-III) for the detection of CT. They also had samples taken from both cervix and urethra for cultivation on McCoy's cells and testing with an enzyme immunoassay (Chlamydiazyme), plus verification of positive samples in the enzyme immunoassay (EIA) with monoclonal antibodies against CT. The urethral samples were compared against the urinary samples with regard to sensitivity and specificity in detecting CT. Women with a positive culture for CT and/or a positive verified EIA from either the cervix or the urethra, were regarded as "true" infections with CT. The prevalence of CT was 12.2%. The urinary EIA sample had a sensitivity of 84% whereas the urethral EIA sample had a sensitivity of 57%. The specificity was 98% and 100% for the urinary samples, and the urethral samples respectively. It is concluded that the urinary sample is superior to the urethral sample, and that the urinary sample could be used for screening programs, to detect CT among women.

The value of urine samples from men with non-gonococcal urethritis for the detection of Chlamydia trachomatis

Chlamydia trachomatis was sought at first and subsequent clinic visits in urethral swabs and urines from 112 heterosexual men with acute non-gonococcal urethritis (NGU). In comparison with a urethral swab tested by Micro Trak (MT), a urine deposit tested in the same way was 90% as sensitive. Examining a urine deposit by the enzyme immunoassay IDEIA was a little less sensitive (89%) than examining a similar deposit by MT, and was less sensitive (82%) than examining a urethral swab by MT. The results of testing urines were little influenced by collecting them either before or after swabbing the urethra, and there was evidence that examining all of a urine sample by IDEIA would have increased sensitivity. Overall, 55 (49%) of the men were diagnosed as C trachomatis-positive based on the results of testing both a urethral swab and a urine sample. Furthermore, a small numbers of chlamydiae were detected by examining urine by MT and, to a lesser extent, by IDEIA, so that there is no reason why this non-invasive approach should not be successful in men other than those with acute NGU.

Rapid, on-site diagnosis of chlamydial urethritis in men by detection of antigens in urethral swabs and urine

First-void urine (FVU) sediments of 240 men were tested for Chlamydia trachomatis antigens by two enzyme immunoassays, TestPack Chlamydia (15 min) and Chlamydiazyme (3.5 h), and the results were compared with urethral swab culture results. The sensitivity and specificity on FVU sediment for TestPack Chlamydia were 76.2% (32 of 42 specimens) and 95.5% (189 of 198 specimens) versus 81.0% (34 of 42 specimens) and 96.5% (191 of 198 specimens) for Chlamydiazyme, respectively. Rapid, on-site detection of chlamydial antigen in male FVU would shorten the infectious period by hastening diagnosis and treatment.

Evaluation of three Chlamydia trachomatis immunoassays with an unbiased, noninvasive clinical sample

First-catch early morning urine samples from patients attending a genitourinary medicine clinic were tested by three different enzyme immunoassays. The results suggest significant differences in the sensitivities and specificities of the different assays. The direct visualization of elementary bodies in urine deposits by direct immunofluorescence was used as the "gold standard," using a monoclonal antibody with a different epitope specificity from those of antibodies used in the enzyme-linked immunosorbent assays. We report for the first time that urine specimens represent an unbiased sample, free of the inherent sampling errors associated with other genital specimens. We feel that urine is a valid specimen for use in any evaluation study of new assays directed towards the detection of Chlamydia trachomatis.

A new look at the diagnosis of infection of the urinary tract and its adjacent structures

The criterion enunciated by Kass for interpreting the quantitative examination of urine is critically reappraised. The role of organisms other than those of the aerobic bowel flora, especially fastidious organisms, in urinary tract infections is discussed in detail. Clinical microbiologists are urged to pay more attention to the bacteriological examination of urine and to play a greater part in the diagnosis and treatment of infections of the urinary tract and its adjacent structures.