Detection of Chlamydia trachomatis in first-void urine from men and women as an alternative to swabs

BACKGROUND: Ideally, an effective preventive strategy for the control of Chlamydia trachomatis infection should take into account the following attributes: rapid and simple specimen collection, low cost and noninvasive test processing. Therefore, we compared the performance profile of urine-based detection of C. trachomatis antigen in first-void urine with that of testing urethral and endocervical samples in men and women. MATERIAL AND METHODS: Urethral and endocervical samples and first-void urine from 285 men and 192 women attending the Sexually Transmitted Diseases Outpatient Clinic at the Medical University in Plovdiv, Bulgaria were tested using direct immunofluorescence assay (DFA) (MicroTrak, Syva, Palo Alto, CA, USA). RESULTS: Seventy (25%) of all men tested were positive for C. trachomatis antigen in either urethral or urine samples. 65 men (93%) had both a positive urethral and urine sample, three men (4%) had only a positive urethral sample and two (3%) had only a positive urine sample. Thirty-five women (18%) had C. trachomatis infection. Twenty-six women (74%) had both a positive endocervical and urethral sample, 6 (17%) had only a positive endocervical sample and 3 (8%) had only a positive urethral sample. All women with positive urethral samples tested positive on their urine samples. Two of the women with a negative urethral sample and a positive endocervical sample had a positive urine sample. CONCLUSIONS: These results show that using direct immunofluorescence assay on first-void urine samples is a reliable noninvasive method which can replace urethral swabs in the diagnosis of C. trachomatis infection in symptomatic men. Urine-based strategies are also an acceptable alternative for the diagnosis of C. trachomatis infection in symptomatic women when it is not possible to obtain an urogenital sample.     

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.     

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.     

Lowering the cut off value of an automated chlamydia enzyme immunoassay and confirmation by PCR and direct immunofluorescent antibody test

AIMS: To increase the sensitivity of an automated chlamydia enzyme immunoassay by significantly lowering its cut off value, and to maintain specificity by confirmation with polymerase chain reaction (PCR) and direct immunofluorescent antibody test (DFA). METHODS: Over five months, the cut off value of the enzyme immunoassay used to screen urogenital samples for chlamydia antigen was reduced from 80 to 10. Samples with a test value of 10 or above were further tested with a commercial PCR assay. All samples during the first three months and discrepant samples during the last two months of the study were also tested with the DFA. RESULTS: 3250 urogenital swabs (1246 urethral, 1335 endocervical, 669 pooled urethral/endocervical) from 1246 males and 2004 females were processed. Using the manufacturer's recommended cut off of 80, the enzyme immunoassay identified chlamydia antigen in 134 samples (4.1%). Using the lower cut off value of 10 and either PCR or DFA as the confirmatory test, Chlamydia trachomatis was identified in 178 samples (5.5%). Thus, 45 additional positive samples were identified and the confirmed detection rate was increased by 33.8% (45/133). Excluding equivocal PCR results, the concordance between DFA and PCR was 91.8%. This strategy increased the detection rate by 2.1% in men and 0.9% in women (significant only in men). In female patients, pooled urethral/endocervical swabs as a specimen gave a significantly higher yield than endocervical swabs regardless of whether the lower cut off strategy was used. CONCLUSIONS: This strategy of significantly lowering the cut off test value with confirmation on the same specimen by either PCR or DFA is feasible and cost effective. The use of pooled urethral/ endocervical specimens in females should be considered routinely as detection rate was significantly improved.     

Inhibition of PCR in genital and urine specimens submitted for Chlamydia trachomatis testing

We determined the frequency of PCR inhibition in genital and urine specimens submitted for Chlamydia trachomatis testing using the internal control DNA provided with the COBAS AMPLICOR C. trachomatis test and assessed methods to remove it. Inhibition occurred in 65 of 906 (7%) cervical swabs, 23 of 51 (45%) urethral swabs, and 2 of 175 (1.1%) urine samples. Overall, inhibition was eliminated in processed specimens after storage at 4 degrees C in 77 of 90 specimens (86%), freezing at -70 degrees C in 59 of 82 specimens (72%), storage at 4 degrees C followed by either 1:100 dilution in 37 of 43 specimens (86%) or 1:10 dilution in 42 of 47 specimens (89%), and phenol-chloroform extraction in 79 of 80 specimens (99%). No positive specimens were missed due to inhibition. We conclude that PCR inhibition is rare with urine specimens and infrequent with endocervical swabs but occurs frequently with urethral swabs. The frequency of PCR inhibition may be significantly reduced by methods which can be easily incorporated into the processing of specimens.     

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.     

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.     

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.     

Thymus size in infants from birth until 24 months of age evaluated by ultrasound. A longitudinal prediction model for the thymic index

To determine whether an absence of leukocytes in semen and urine predicts an absence of Chlamydia trachomatis in asymptomatic infertile men, chlamydial DNA was detected in subjects' semen and urine by ligase chain reaction (LCR). Ninety-eight infertile men were studied, including 39 cases of oligozoospermia, 19 of azoospermia, 16 of asthenozoospermia, and 24 of normozoospermia. None of the subjects had pyospermia or pyuria. C. trachomatis was detected by LCR. Antichlamydial and antisperm antibody were also measured. C. trachomatis was detected by LCR in the semen of only 1 of 98 patients (1.02%), but not in the urine samples. In C. trachomatis-positive patients LCR, IgG, and IgA levels were higher than normal. No antisperm antibody was detected. Even if leukocytes are not observed in the semen and urine of asymptomatic infertile men, the presence of C. trachomatis in semen specimens is rarely observed. Therefore, it should be noted that the presence of C. trachomatis in such cases is addressed in the context of artificial insemination and other assisted reproductive technologies.     

The marital context of end-stage renal disease: illness intrusiveness and perceived changes in family environment

The use of PCR assays as a fast and reliable method is constantly improving and easing microbiological diagnosis. We used a polymerase chain reaction (PCR) assay designed to detect Mycoplasma genitalium and Chlamydia trachomatis in urethral swab samples of 56 males with urethritis and 44 asymptomatic patients as a control group. The PCR assay provides an amplification of target sequence within MgPa (M. genitalium protein attachment) gene. Results indicated that M. genitalium was present in 6 (10.7%) patients with urethritis and none in the control group. Eleven of 56 (17.8%) patients were positive for Chlamydia trachomatis when tested by an outer membrane protein primer-based PCR. The amplified DNA fragments were homogeneous as shown by restriction enzyme analysis and found to be consistent with the published sequences. The PCR assay employed was as reliable as the cultural method in detecting C. trachomatis in the urethral swabs of patients with urethritis (100% of sensitivity when compared with the cultural method) and it has been revealed as an essential method for detection of M. genitalium.     

Mouse NK1.1+ T cells: a new family of T cells

A ligase chain reaction (LCR) DNA amplification assay that targeted the cryptic plasmid of Chlamydia trachomatis was developed to detect C. trachomatis urogenital tract infection. The objectives of this study were to determine the cutoff and analytic performance of the LCR assay and to characterize the effectiveness of its postdetection contamination control method. The assay's cutoff was determined after receiver-operator characteristic (ROC) analysis of 4660 clinical data points. The assay detected one infectious unit per reaction of each of the 15 C. trachomatis serovars and did not cross-react with 13 Chlamydia pneumoniae strains, 13 Chlamydia psittaci strains, and 87 other bacteria, fungi, parasites, or viruses. In addition, the assay did not detect 77 processed urine specimens collected from patients with urinary tract infections caused by yeast or bacteria other than C. trachomatis. The assay was sufficiently precise to detect consistently two infectious units of C. trachomatis per reaction. False-positive assay results attributable to contamination with amplified product were minimized by the use of standard procedures as well as by a postdetection chemical inactivation method that could reduce the amount of amplified LCR product by a factor of > or = 10(7).     

Development and evaluation of screening strategies for Chlamydia trachomatis infections in an STD clinic

OBJECTIVES: To identify predictors for Chlamydia trachomatis infection among visitors of an STD clinic in Amsterdam in 1986-1988. To design predictor-based screening programmes for C trachomatis. To evaluate the chosen screening strategy in 1993. METHODS: In 1986-1988, 947 heterosexual men and 648 women participated in the study. A medical history was recorded, a physical examination took place and samples were taken for laboratory diagnostics. Information for 1993 was available from routine databases. RESULTS: C trachomatis infections in heterosexual men in 1986-1988 (prevalence 15.8%) were independently associated with: age under 26 years, being an STD contact, coitarche below 13, last sexual contact with a non-prostitute, (muco)-purulent urethral discharge and ten or more leukocytes per microscopic field of urethral smear or urine. For women (prevalence 21.5%) independent predictors were age under 26, no history of STD, being an STD contact, cervical friability, (muco)purulent cervical discharge, presence of clue cells and ten or more leukocytes per field of urethral smear. Screening men with one anamnestic predictor for C trachomatis and ten or more leukocytes in smear or urine (59% of men) would detect 93% of the cases in 1986-1988. For females only universal screening proved to be suitable. After the introduction of a screening strategy in 1989 (universal for women, indicated by urethritis for men), a strong decline was found in the C trachomatis prevalence for all subgroups in 1993, excluding prostitute's clients and Turkish men. CONCLUSIONS: In 1993 the overall C trachomatis prevalence had declined among the attendants of the STD clinic. It seems likely that this fall was caused both by the screening programme and the reduction of risk behaviour.     

Detection of Chlamydia trachomatis infection by PCR in first voided urines in men

The goal of this study was to evaluate whether the new commercially available PCR-based assay Amplicor C. trachomatis (Roche Molecular Systems) could improve the diagnosis of chlamydial urogenital infections in men, compared with cell culture of C. trachomatis considered as the reference method. A total of 466 men attending the STD clinic were tested by the Amplicor test in urine and by cell culture in urethra. The prevalence of C. trachomatis was 13.7% (64/466) by cell culture and 14.4% (67/466) by the Amplicor test. After resolution of the discrepant results, the sensitivity of culture was 91.4% in male urethral specimens. The resolved sensitivity of the PCR assay was 92.7% in male urine and the specificity was 99.5%. We concluded that this rapid PCR-based assay showed an improvement in quality for diagnosing C. trachomatis infections in men.     

Pooling of urine samples for screening for Neisseria gonorrhoeae by ligase chain reaction: accuracy and application

The accuracy of detection of genital Neisseria gonorrhoeae infection in pooled urine samples by ligase chain reaction (LCR) was examined in three populations. Firstly, urine specimens from 300 female military recruits (FMR) were tested by LCR individually and in pools of four and six. Secondly, 300 urine specimens from middle-school students (MSS) were tested individually by LCR, and then the processed specimens were stored frozen for subsequent testing in pools of 4 and 10. Thirdly, 600 frozen urine specimens from high-school students (HSS) were tested by using the LCR pooling algorithm, i.e., testing processed specimens in pools of four in one test unit dose, and retesting individual specimens from positive pools. Finally, the pooling algorithm results were compared to culture results for a subset of 344 students from the original 600 HSS from whom cervical or urethral samples were taken at the discretion of the school nurse practitioners. Compared to individual testing of specimens by LCR in the FMR population, the pooling-by-four algorithm was 100% sensitive (5 of 5) and 100% pool specific (70 of 70), and the pool-by-six algorithm was 100% sensitive (5 of 5) and 100% pool specific (45 of 45). In the MSS population, the pool-by-4 algorithm was 95.8% sensitive (23 of 24) and 100% (52 of 52) pool specific, and the pool-by-10 algorithm was 95.8% sensitive (23 of 24) and 100% (17 of 17) pool specific. In the subset of 344 HSS from whom endocervical or urethral specimens were collected for culture, 31 were positive by LCR in urine and 26 were positive by culture. After results discrepant between culture and LCR were adjudicated by a confirmatory LCR test, the pooling algorithm was 93.8% (30 of 32) sensitive and 99.7% (311 of 312) specific. Culture from these 344 HSS was 81.3% (26 of 32) sensitive. The pooling algorithm reduced the cost of the N. gonorrhoeae LCR assay by 60% compared to individual testing of the HSS specimens and was both sensitive and specific.     

Ligase chain reaction for detection of Neisseria gonorrhoeae in urogenital swabs

The ligase chain reaction (LCR) is an in vitro nucleic acid amplification technique that exponentially amplifies targeted DNA sequences. In a multicenter study, we evaluated the use of a 4-h LCR-based assay for the diagnosis of Neisseria gonorrhoeae infection of the cervix and male urethra. The LCR results were compared with those of culture for N. gonorrhoeae by using selective media. This assay amplifies target sequences within the N. gonorrhoeae opacity gene. Discordant LCR-positive and culture-negative specimens were further evaluated by testing by another LCR assay which used N. gonorrhoeae-specific pilin probe sets. A total of 1,539 female endocervical specimens and 808 male urethral swab specimens were evaluated in the study. An expanded "gold standard" was defined to include all culture-positive as well as culture-negative, confirmed LCR-positive specimens. After resolution of discrepant samples, the sensitivities of the N. gonorrhoeae LCR assays for the female and male specimens were 97.3 and 98.5%, respectively, with specificities of 99.6 and 99.8%, respectively. Resolved culture sensitivities were 83.9 and 96.5% for the female and male specimens, respectively. The LCR assay for gonorrhea is a rapid, highly sensitive nonculture method for detecting gonococcal infection of the cervix and male urethra.     

Evaluation of 2-SP transport medium for detection of Chlamydia trachomatis and Neisseria gonorrhoeae by two automated amplification systems and culture for chlamydia

AIMS: To assess the performance of 2-sucrose-phosphate based transport medium (2-SP) for the detection of Chlamydia trachomatis and Neisseria gonorrhoeae by an automated commercial polymerase chain reaction (PCR) and ligase chain reaction (LCR) compared to centrifugation culture on McCoy cells for C trachomatis. Second, to compare both amplification systems for initial diagnostic testing of a low prevalence population for sexually transmitted diseases. METHODS: Four hundred and eighty one consecutive urogenital and conjunctival specimens were examined. All tests were performed on the same specimen collected with a dacron swab and transported in 2-SP medium. Samples that were positive by culture or by both PCR and LCR were considered to be true positives. RESULTS: The prevalences of C trachomatis and of N gonorrhoeae were 2.7% and 0.4%, respectively. PCR had a resolved sensitivity and specificity of 100% and 99.8%, respectively, for C trachomatis, and 100% and 98.9%, respectively, for N gonorrhoeae. LCR was 100% sensitive and specific for both pathogens. The resolved sensitivity of the shell vial assay was 85%. No culture positive sample would have been missed by PCR or LCR. The inhibition rate for PCR was 4.8%. CONCLUSIONS: 2-SP medium proved to be suitable for both PCR and LCR. It is not limited to any one test manufacturer and allows the performance of amplification techniques and viral and chlamydia culture from the same specimen. The LCR was more reliable than PCR on initial testing. However, hands on time is longer, and no amplification control is available for LCR.     

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.     

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.