Double immunochemical screening test (hemoglobin and albumin) for the detection of occult intestinal bleeding

BACKGROUND AND OBJECTIVES: Chlamydia trachomatis antigen testing of clinical specimens is replacing culture as the test of choice. Because of a potential for false positive results in low prevalence populations, there is an apparent need for confirming specimens positive by enzyme immunoassay (EIA). GOAL OF THIS STUDY: To examine specimens falsely positive in the Chlamydiazyme EIA assay according to gender and specimen type. STUDY DESIGN: Testing of genitourinary specimens from men and women consecutively enrolled from five health care delivery sources in an urban Canadian population. All specimens were initially tested in the Chlamydiazyme test and all positives repeated in a confirmatory blocking assay provided by the manufacturer. Additional confirmatory testing was performed using immunofluorescence (IF) staining for C. trachomatis elementary bodies (EB's) and polymerase chain reaction (PCR). RESULTS: From Jan. 1, 1990 to June 1, 1991, multiple specimens from 656 men and 5,628 women of varying population prevalences were screened. EIA-positive specimens from women had a repeat negative rate of 22% to 27% from cervical swabs and 29% from urethral swabs. Male urethral swabs had a high repeat negative rate of 22% when EIA was the only positive test, but 2.4% when the specimen was positive by EIA and culture. EIA-positive first void urine (FVU) specimens from men had a repeat negative rate of 8.7% as opposed to 17% to 32% from women. Only 1.7% (2/115) of male FVU did not block compared to rates of 47% (22/47) to 80% (4/5) in FVU from women. Analysis of EIA optical densities (OD's) and EB counts showed an association between the absorbance range 0.1 to 1.4 OD and 0-85 EB's. The greatest number of EB's and highest OD's were seen with cervical specimens, followed by urine and urethral specimens in women infected at all three specimens. All 55 specimens that did not confirm in the blocking test had no EB's and a convenience sample of seven were negative by PCR. All of a subset of 50 blocked specimens contained EB's or were positive by PCR. CONCLUSIONS: Although a variable proportion of specimens may not repeat positive in the EIA, use of the blocking reagent to confirm the repeat positives is highly recommended and the rate of blocking may be heavily influenced by gender and specimen type.     

Comparison of performances of two commercially available tests, a PCR assay and a ligase chain reaction test, in detection of urogenital Chlamydia trachomatis infection

The diagnostic performance of a PCR test (Roche Cobas Amplicor CT/NG Test) and that of a ligase chain reaction (LCR) test (Abbott LCx Chlamydia trachomatis assay) were compared by using endocervical and urethral swab specimen culture as a reference test. First-void urine (FVU) and endocervical and urethral swab specimens were collected from 1,015 unselected patients attending a sexually transmitted disease clinic and a clinic for adolescents in Helsinki, Finland. Chlamydia trachomatis was cultured from samples from the endocervix or urethra. PCR was performed with fresh and frozen urine and the culture transport medium. LCR was performed with fresh and frozen urine and LCx swab transport medium. Diagnostic consistency and diagnostic accuracy were statistically tested. The test results were identical for 984 patients (97%). Discrepant results were observed for 31 patients. Overall, LCR and PCR showed excellent kappa coefficients of consistency for both swab and FVU specimens (0.93 and 0.95, respectively). Sixty-one patients (6%) were culture positive. Testing of FVU by LCR or PCR increased the overall positivity rates to 7.0 and 7.7%, respectively. While PCR of FVU detected the greatest number of C. trachomatis infections (sensitivity, 96.1%), for some PCR-positive FVU specimens the results could not be confirmed (specificity, 99.6%). PCR and LCR were more sensitive than culture (sensitivities, 92 and 93% versus 79% for culture) in the diagnosis of genital C. trachomatis infection. In conclusion, both tests can be recommended for use in the clinical laboratory and for the screening of asymptomatic C. trachomatis infections.     

Preconditioning with cromakalim improves long-term myocardial preservation for heart transplantation

Polymerase chain reaction (PCR) and ligase chain reaction (LCR) were compared for the diagnosis of Chlamydia trachomatis infections by testing urine specimens from 408 high school female students. After therapy, sequential urine specimens were tested to determine persistence of chlamydial DNA in urine. Baseline PCR of cervical specimens was positive in 53 (13.0%) students, and PCR and LCR of urine specimens were positive in 63 (15.4%) and 60 (14.7%), respectively. After discrepant analysis, 64 (15.7%) patients could be confirmed as truly infected. Follow-up urine specimens from 33 infected patients demonstrated that at 1-3 days after therapy, PCR and LCR were positive for 40% and 73.3%, respectively. Only at 15 days after therapy did all specimens test negative. Urine tests for Chlamydia organisms should not be used as a test of cure within 3 weeks after treatment. Use of urine assays for screening sexually active adolescents has the potential to significantly improve control of chlamydial infections.     

Effects of SL-probiotic preparation on the body weight and phagocytosis of white mice

Specimens from 15 young patients presenting with acute epididymitis were tested for the presence of Chlamydia trachomatis by an enzyme immunoassay (EIA), polymerase chain reaction (PCR), and for other bacteria by standard laboratory techniques. C. trachomatis urethral infection was detected in 3 patients by an EIA test of the urethral swabs (20%) and in 13 patients by the PCR (87%). This difference in detection rate was statistically significant (p < 0.005). Thirteen specimens were positive by the PCR, but only three of them were positive by the EIA method. These findings indicate that the PCR assay is a highly sensitive assay for the detection of C. trachomatis in male urine specimens and provides a noninvasive technique for routine screening of chlamydia infection in the patient with acute epididymitis.     

Multiplex AMPLICOR PCR screening for Chlamydia trachomatis and Neisseria gonorrhoeae in women attenting non-sexually transmitted disease clinics. The European Chlamydia Epidemiology Group

A new PCR kit (AMPLICOR CT/NG; Roche Diagnostic Systems, Inc., Branchburg, N.J.) was used as a screening tool for the detection of Chlamydia trachomatis and Neisseria gonorrhoeae in first-void urine (FVU) specimens from 3,340 asymptomatic women attending European health care units for contraceptive advice or pregnancy termination. All samples were kept frozen (-20 degrees C) prior to testing. Chlamydia-positive samples were retested once by the plasmid-based PCR kit and also by a major outer membrane protein (MOMP) primer-based PCR. Discrepancies were resolved by using the direct immunofluorescence test (DIF) with the centrifuged sediment of the FVU specimens. Samples positive for N. gonorrhoeae were retested by chromosomal primer-based PCR and verified by a 16S RNA PCR. Of the samples tested, 1.8% were considered inhibitory by using the internal amplification control. Of 81 samples positive for C. trachomatis, 74 samples were positive by both plasmid- and MOMP-based PCRs, 6 samples were positive by plasmid-based PCR and DIF, and one sample was positive by both MOMP-based PCR and DIF. Nine samples (0.3%) were positive for N. gonorrhoeae by the chromosomal primer-based PCR; however, none of the results could be confirmed. The test offers the unique ability to identify inhibition of amplification with the optional internal control.     

Concordance of PCR and antibody results from HIV testing of injecting drug users

Standard HIV-1 testing relies on the enzyme immunoassay (EIA) for detecting antibodies specific to HIV-1. This technique may misclassify persons as HIV-1-negative in instances where testing follows infection but precedes development of antibody to HIV-1. To evaluate the occurrence of HIV infection in the absence of positive antibody, polymerase chain reaction (PCR) for viral DNA in the blood has been applied. Research comparing these two testing techniques has generally focused on populations of homosexual and bisexual men. This study compares PCR and antibody testing of 337 injecting drug users recruited from street settings in San Francisco. Of 286 HIV-1 antibody-negative samples, 3 (1.0%) were PCR-positive. Of 49 HIV-1 antibody-positive samples, 1 (2.0%) was PCR-negative. Two samples were antibody-indeterminate and PCR-negative. This yielded an overall concordance of 331/335 (98.8%), excluding the indeterminate results. These results suggest that current antibody methodology is adequate. However, misclassification among recently infected individuals may occur, which is of concern in high-incidence groups.     

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

Two commercially available nucleic acid-based tests, ligase chain reaction (LCR; Abbott Laboratories) and PCR (Roche Diagnostics), for the detection of Chlamydia trachomatis in male and female urine samples were compared with culture and enzyme immunoassay (EIA) (Microtrak; Syva) for C. trachomatis detection in genital samples. The samples were collected from 1,005 patients who attended a sexually transmitted disease clinic. In this study population, the prevalence of the infection was 4%. Specimens which were reactive in any of the tests were retested with a different PCR test using primers directed against the major outer membrane protein gene. With a "gold standard" of a positive culture, or any other positive test result if it was confirmed by an independent test, the Roche PCR (95% sensitive, 99.9% specific) was more sensitive than the LCR (75% sensitive, 100% specific) (chi2, P < 0.0001) while both tests were more sensitive than culture (58% sensitive, 100% specific) or EIA (45% sensitive, 100% specific) (chi2, P < 0.001). The Roche PCR and Abbott LCR tests of urine identified 65% and 30% more positive patients, respectively, than did testing by culture of urethral or cervical specimens. Nucleic acid testing of urine specimens for C. trachomatis is a more sensitive and convenient method for the detection of genital infection.     

Detection of Neisseria gonorrhoeae and Chlamydia trachomatis in genitourinary specimens from men and women by a coamplification PCR assay

A coamplification PCR test for the direct detection of Neisseria gonorrhoeae and Chlamydia trachomatis in urethral and endocervical swabs and urine samples from men and women was compared to standard culture techniques. Processed specimens were amplified in single reaction tubes containing primers for both organisms, and PCR products were detected by a colorimetric microwell plate hybridization assay specific for each pathogen. Of 344 specimens from men, 45 (13.1%) urine specimens were PCR positive for C. trachomatis, 51 (14.8%) urethral swab specimens were PCR positive, and 29 urethral swab specimens (8.4%) were culture positive. After analysis of discrepancies, the resolved sensitivity and specificity of PCR for C. trachomatis were 96.2 and 99.3%, respectively, in urethral swab specimens, compared to 88.2 and 98.6% for urine specimens. Of the 192 specimens from women, 28 (14.6%) urine specimens were PCR positive for C. trachomatis, 32 (16.7%) endocervical specimens were PCR positive, and 19 (9.9%) endocervical specimens were culture positive. After analysis of discrepancies, the resolved sensitivity and specificity of PCR for C. trachomatis for endocervical specimens were both 100% compared to 100 and 99.4%, respectively, for urine specimens from women. In men, 68 (19.8%) urine specimens were PCR positive for N. gonorrhoeae, 73 (21.2%) urethral swabs were PCR positive, and 59 (17.2%) urethral swabs were culture positive. After analysis of discrepancies, the resolved sensitivity and specificity of PCR for N. gonorrhoeae were 97.3 and 97.0%, respectively, for urethral specimens compared to 94.4 and 98.5% for urine specimens. In women, 18 (9.4%) urine specimens were PCR positive for N. gonorrhoeae, 23 (12.0%) were endocervical swab PCR positive, and 15 (7.8%) endocervical specimens were culture positive. After analysis of discrepancies, the resolved sensitivity and specificity of PCR for N. gonorrhoeae were 100 and 99.4%, respectively, for endocervical specimens compared to 90.0 and 95.9% for female urine specimens. These results indicate that a multiplex PCR is highly sensitive for detecting both C. trachomatis and N. gonorrhoeae from a single urine or genital swab, providing a more cost-effective way of screening multiple pathogens.     

An examination of the occurrence of surgical wound infection following equine orthopaedic surgery (1981-1990)

First-void urine specimens, collected from 309 military recruits, 246 male adolescent gymnasium students and 194 patients consulting venereal disease clinics, were studied for the presence of Chlamydia trachomatis with the use of antigen detection tests--two enzyme immunoassays (EIA) and a direct immunofluorescence test (DIF; Syva MicroTrak). Urethral swabs were collected when discrepancies between the EIA and DIF tests were detected. The patient was regarded as positive when the culture result was positive or when two antigen detection tests corraborated one another. The Syva MicroTrak EIA and DIF tests were more sensitive than the Orion EIA, i.e. 98.5%, 99.2% and 74%, respectively. This was true when testing both low- and high-risk groups, with a prevalence of chlamydial infection ranging from 0.4% to 58.6%. All three tests were highly specific. The positive predictive values for the Syva MicroTrak EIA, the DIF and the Orion EIA were 99.2%, 100% and 100%, respectively and the negative predictive values 99.8%, 99.8% and 94.8%, respectively.     

Quantification of Chlamydia trachomatis in cervical and urine specimens from women attending a genitourinary medicine clinic: implications for screening strategies

Population screening and intervention programmes can reduce the prevalence and incidence of infection with Chlamydia trachomatis, especially if sensitive molecular diagnostic tests are used. However, diagnostic tests that perform well on genitourinary medicine (GUM) clinic populations may be less useful for screening, particularly if the majority of infected subjects are asymptomatic and their samples contain fewer organisms. We have compared the extent of low organism load in cervical and urine samples from symptomatic and asymptomatic chlamydia-positive women, by using a direct fluorescent antibody staining method and counting the chlamydial elementary bodies (EBs). We have investigated the ability of an enzyme immunoassay (EIA; MicroTrak) and a DNA amplification (ligase chain reaction; LCR) assay to detect low numbers of organisms in cervical samples and the ability of the LCR assay to detect low numbers of organisms in urine. A low organism load (< 10 EBs) was seen by direct fluorescent antibody (DFA) staining in about 30% of cervical samples and in about 75% of urines from chlamydia-positive women; the proportions in symptomatic women were not significantly different from those in asymptomatic women. The EIA identified only 16% of cervical samples that contained < 10 EBs by DFA staining; the LCR identified 100% of cervical samples and 93% of urine samples that contained < 10 EBs by DFA staining. The findings suggest that the ability of chlamydial diagnostic tests to identify positive women should be similar among patients attending a GUM clinic and those taking part in a population screening programme, and that sensitive molecular assays such as the LCR should identify subjects with a low organism load in both groups.     

Antigen retrieval: p53 staining in benign, pre-malignant and malignant tissues of the larynx

Verification of specimens positive for Chlamydia trachomatis by enzyme immunoassay (EIA) has been recommended when testing low prevalence populations. This study compared direct fluorescent antibody (DFA) and blocking antibody (BLA) verification assays in specimens presumptively positive for C. trachomatis by the Syva Microtrak II EIA. Of 1785 specimens originally tested by EIA, 96 were presumptively positive for C. trachomatis. Verification assays were concordant in 86 specimens (69 positive, 17 negative); nine of the remaining samples gave positive results in a second EIA and one was unresolved. Both verification assays gave some false-negative results. When initial EIA absorbance values were correlated with verified results, all EIA false positive results had absorbances in the low range (less than a three-fold increase over assay cut-off values). Verification of EIA results by both DFA and BLA was effective in detecting false positive results, but confining verification to low-value positive specimens could be considered for cost effective C. trachomatis testing.     

Perflubron as a gastrointestinal MR imaging contrast agent in the pediatric population

A microplate enzyme immunoassay (EIA) for the detection of lysergic acid diethylamide (LSD) in human urine was developed. The assay kit is designed around an LSD derivative coated on the wall of microplate wells with preservatives and stabilizers. Sample and rabbit anti-LSD are added to the microplate well. The immobilized LSD and LSD present in specimens compete for the opportunity to bind to the anti-LSD antibodies. An anti-rabbit antibody labeled with horseradish peroxidase is used to provide the assay signal, which is inversely proportional to the concentration of LSD in the sample. The assay requires a 25-microL urine sample and three consecutive incubation periods of 60, 30, and 30 min at room temperature. The assay was tested with a variety of drugs, including ergot alkaloids spiked into drug-free urine at up to 100,000 ng/mL without cross-reaction. Nor-LSD was shown to cross-react between 16% and 28%, depending on its concentration. Of the other compounds tested, only ergonovine demonstrated slight cross-reactivity at approximately 0.0008%. The assay is designed to be used with a qualitative cutoff of 0.5 ng/mL. Precision testing at 0.5 ng/mL gave a coefficient of variation (CV) of 6% based on 20 replicates. The CV at 0.375 ng/mL (cutoff, -25%) was 5.2% and at 0.625 ng/mL was 6.6%. Precision at other concentrations within the range of the calibration curve gave similar results both intra- and interassay. Clinical performance of the assay was compared with that of a commercial radioimmunoassay (RIA). Comparable performance was observed with both methods, each screening a total of 458 samples as negative and 17 samples as positive relative to a 0.5 ng/mL cutoff. The EIA found an additional three positive samples that were negative by RIA. The EIA is suitable for the screening of urine samples for the presence of LSD. Preliminary indications are that the assay is also suitable for use with whole blood specimens. The assay can be performed manually or be fully automated and without the need for radioactivity; it can be used in any laboratory.     

Detection of Ureaplasma urealyticum by PCR and biovar determination by liquid hybridization

An assay which combines the direct detection of Ureaplasma urealyticum with biovar determination was developed and applied to 618 urogenital specimens. U. urealyticum was detected by inhibitor-controlled PCR. A 429-bp fragment of the urease gene was amplified. The amplicons were labelled with digoxigenin during PCR. Biovar determination was performed by liquid hybridization with biotin-labelled biovar-specific probes, and the hybrids were detected with peroxidase-conjugated sheep anti-digoxigenin immunoglobulin G Fab fragments. Results of PCR and culture for 453 urogenital specimens from women and 105 urethral specimens from men could be compared. Among the specimens from women, 63% were PCR positive as well as culture positive, 0.9% were positive only by PCR, and 4% were positive only by culture. Among the specimens from men, 15% were PCR positive as well as culture positive, 1% were positive only by PCR, and 9% were positive only by culture. By using culture as the reference method, the PCR had a sensitivity of 94% and a specificity of 98% when applied to specimens from women and a sensitivity of 64% and a specificity of 99% when applied to specimens from men. Overall, 80% of the PCR-positive specimens contained biovar 1,13.5% contained biovar 2, and 6.5% contained both biovars.     

Interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) enhance lipopolysaccharide binding to neutrophils via CD14

BACKGROUND: Microalbuminuria is an early marker of prognostic significance in diabetic renal disease. However, testing for microalbuminuria in a timed sample of urine using the double antibody radioimmunoassay (RIA) method is cumbersome and requires special laboratory facilities. Recently, a test strip for microalbuminuria, the Micral Test was available and we evaluated the performance of this test strip as a screening method for detection of microalbuminuria. METHODS: One hundred consecutive diabetic patients who were tested to be dipstick-negative (Albustix) for proteinuria were enrolled for the study. Micral Tests were performed on a paired first morning and random urine specimen from the same patient and the results compared with a timed 24-hour urine measurement of urine albumin excretion using the RIA method. RESULTS: Eighteen specimens were tested positive by the RIA method with a urinary albumin range of 32-177 mg/24 hours. With the Micral Test, the following sensitivity, specificity, positive and negative predictive values were obtained: 66.7%. 97.6%, 85.7% and 93.0% for the first morning urine specimens, and 77.8%, 91.5%, 66.7% and 94.9% for the random urine specimens. CONCLUSIONS: These results suggest that Micral Test with either the first morning or random urine specimen offers a simple, reliable, rapid and convenient method for screening of microalbuminuria in the diabetic patient.     

Varying results for immunoassay screening kits for cotinine level.

Our earlier study found that although enzyme-linked immunosorbent analysis (ELISA) screening assays for urine cotinine indicated use in former smoking treatment patients who reported abstinence, this finding was sometimes incorrect when validated against gas chromatography/mass spectrometry (GC/ MS; P. Gariti, A. I. Alterman, R. Ehrmann, F. D. Mulvaney, & C. P. O'Brien, 2002). In the current validation study, separate urine samples of 71 of these same patients were reanalyzed by an independent laboratory in blinded fashion using a screening enzyme immunoassay (EIA) analysis and GC/MS confirmation. EIA results showed almost total agreement with confirmatory testing. The findings indicate that use of screening ELISA/EIA for urine cotinine can detect unreported cases of smoking in former patients, but that care is needed in selecting a laboratory for conducting these tests. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Use of lambda phage DNA as a hybrid internal control in a PCR-enzyme immunoassay to detect Chlamydia pneumoniae

An inherent problem in the diagnostic PCR assay is the presence of ill-defined inhibitors of amplification which may cause false-negative results. Addition of an amplifiable fragment of foreign DNA in the PCR to serve as a hybrid internal control (HIC) would allow for a simple way to identify specimens containing inhibitors. Two oligonucleotide hybrid primers were synthesized to contain nucleic acid sequences of the Chlamydia pneumoniae 16S rRNA primers in a position flanking two primers that target the sequences of a 650-bp lambda phage DNA segment. By using the hybrid primers, hybrid DNA comprising a large sequence of lambda phage DNA flanked by short pieces of chlamydia DNA was subsequently generated by PCR, cloned into a plasmid vector, and purified. Plasmids containing the hybrid DNA were diluted and used as a HIC by adding them to each C. pneumoniae PCR test. Consequently, C. pneumoniae primers were able to amplify both chlamydia DNA and the HIC DNA. The production of a 689-bp HIC DNA band on an acrylamide gel indicated that the specimen contained no inhibitors and that internal conditions were compatible with PCR. Subsequently, a biotinylated RNA probe for the HIC was transcribed from a nested sequence of the HIC and was used for its hybridization. Detection of the HIC DNA-RNA hybrid was achieved by enzyme immunoassay (EIA). This PCR-EIA system with a HIC was initially tested with 12 previously PCR-positive and 14 previously PCR-negative specimens. Of the 12 PCR-positive specimens, 11 were reconfirmed as positive; 1 had a negative HIC value, indicating inhibition. Of the 14 previously PCR-negative specimens, 13 were confirmed as true negative; 1 had a negative HIC value, indicating inhibition. The assay was then used with 237 nasopharyngeal specimens from patients with pneumonia. Twenty-one of 237 (8.9%) were positive for C. pneumoniae, and 42 (17.7%) were found to inhibit the PCR. Specimens showing inhibitory activity were diluted 1:10 and were retested. Ten specimens were still inhibitory to the PCR and required further DNA purification. No additional positive samples were detected and 3 nasopharyngeal specimens remained inhibitory to PCR. Coamplification of a HIC DNA can help confirm true-negative PCR results by ruling out the presence of inhibitors of DNA amplification.     

Detection of Helicobacter pylori in stool specimens by PCR and antigen enzyme immunoassay

A highly sensitive seminested PCR assay to detect Helicobacter pylori DNA in feces was developed. PCR with stool specimens and a novel antigen enzyme immunoassay (EIA) for H. pylori detection in feces were evaluated as diagnostic tools and in follow-up with samples from 63 infected and 37 noninfected persons. Infected individuals received eradication therapy followed by endoscopic follow-up 35 days after the start of treatment. At that time, a second stool specimen was obtained from 55 of these patients. Before eradication, the sensitivity of PCR was 93.7% and that of EIA 88.9%. Specificities were 100 and 94.6%, respectively. Of the 55 follow-up specimens, 41 originated from patients from whom H. pylori had been eradicated. Of these, 21 were still positive by PCR and 13 were positive by EIA, indicating that 1 month may be too short a period for follow-up evaluation of stool specimens by these tests.     

Is urine leukocyte esterase test a useful screening method to predict Chlamydia trachomatis infection in women?

We evaluated the use of the leukocyte esterase test (LET) on first-catch urine specimens from women as a screening test to predict infection with Chlamydia trachomatis. For diagnosis, we used Abbott's ligase chain reaction (LCR) on urine specimens and isolation by tissue culture (TC) on cervical brushes. Of 4,053 women attending sexually transmitted disease and family planning clinics, 4.3% (n = 174) were positive by TC and 5.9% (n = 239) were positive by LCR. When LET was compared to TC, the sensitivity, specificity, positive predictive value, and negative predictive value were 54.0, 67.0, 6.8, and 97.0%, respectively. The corresponding performance of LET versus LCR was 53.1, 67.3, 10.1, and 95.8%. Almost half of the laboratory-confirmed chlamydial infections were negative by LET. The low specificity probably reflects multiple causes of pyuria in women and results in a low positive predictive value. LET is neither sensitive nor specific as a predictor of chlamydial infection and cannot be recommended for use as a screening test for C. trachomatis with first-catch urine samples from females from low- or moderate-prevalence populations.     

Antibodies to chlamydia trachomatis in semen and relationship with parameters of male fertility

To screen for infection with Chlamydia trachomatis in semen samples from asymptomatic men in couples consulting for infertility and to determine the relationship of seminal chlamydial antibodies with clinically relevant parameters of male fertility, 197 randomly chosen patients were enrolled in a prospective study. The median duration of infertility was 4 years (range 1-18). Screening for C. trachomatis and chlamydial antibodies of the immunoglobulin (Ig) A and IgG classes were performed in ejaculates and, in parallel, endocervical material from the partners of the patients and serum samples from both partners were evaluated. A comprehensive examination of semen quality included sperm analyses, semen cultures, local antisperm antibody (ASA) testing, the determination of potential infection markers, and sperm-cervical mucus interaction testing in vitro (SCMPT) and in vivo (post-coital testing). Chlamydial IgA antibodies were found in the semen samples of 18.8% (37/197) of the patients, while chlamydial IgG antibodies were found in 8.1% (16/197) of the patients. Screening for C. trachomatis was negative in all semen and cervical specimens. Only 5.5% of men remembered a past genital infection. Chlamydia antibodies (IgA/Ig/G) in semen were significantly correlated with chlamydia IgG antibodies in serum samples (P < 0.001). No marked relationship was found between the presence of seminal chlamydial antibodies and the major parameters of sperm analysis, semen cultures, local ASA and sperm penetration testing as an indicator of functional capacity. Seminal chlamydial antibodies were not significantly associated with potential infection or inflammation markers in aliquots of the same ejaculates. However, a significant relationship of chlamydial antibodies in patients' semen with past genital infections of their female partners was found with clinical relevance for a tubal infertility factor. The results indicate that in asymptomatic patients the presence of chlamydial antibody IgA or IgG in semen is not associated with reduced semen quality, potential seminal infection markers or impaired functional capacity as important determinants of male fertility; however, seminal chlamydial antibodies suggesting a previous sexually transmitted disease are significantly related to a tubal infertility factor of female partners.