Comparison of urine, first and second endourethral swabs for PCR based detection of genital Chlamydia trachomatis infection in male patients

OBJECTIVES: To compare endourethral swabs and urine as diagnostic specimens for the detection of genital Chlamydia trachomatis infection using the polymerase chain reaction (PCR), in male patients attending a genitourinary clinic and to assess whether the first endourethral swab used solely for diagnosing gonococcal infection could be used for C trachomatis detection as well. METHODS: Two endourethral swabs were taken from 80 male patients, in whom the likelihood of genital C trachomatis infection was high. The first swab was used for microscopy and culture for Neisseria gonorrhoeae, before being used for C trachomatis detection. First voided urine specimens were collected from 61 of these patients. All three specimens were processed for C trachomatis DNA detection using the Roche Cobas Amplicor PCR. A diagnosis of genital C trachomatis infection was made if any one of the specimens tested reproducibly positive. Samples from 13 patients showing discrepant PCR results between swabs and/or urine were retested by ligase chain reaction (LCR). RESULTS: Chlamydia trachomatis DNA was detected in 35 (43.8%) of the 80 patients. In 17 of the 35 patients (48.6%), all the genital specimens were positive. However, in 18 (51.4%) patients, one or more of the genital specimens had negative PCR results. Among the 18 patients with discrepant results, urine was found to be a more sensitive diagnostic specimen than the second urethral swab picking up 13 out of 16 positives (81.3%) as opposed to five out of 18 (27.8%). There was no significant difference between the two swabs. Retesting by LCR, of the samples from 13 of the 18 patients with discrepant PCR results confirmed them all as true positives, although as with PCR, not all specimens in the set were concordantly positive. LCR detected all the 13 positives in urine, while there was no difference in the detection rate between the first and the second urethral swabs. CONCLUSIONS: Urine appeared to be a better diagnostic specimen than the conventional second endourethral swab for C trachomatis detection by PCR in this cohort of male patients. There was no difference between the first swab, intended primarily for N gonorrhoeae testing and the second swab intended for C trachomatis detection. This raises questions over the need for the conventional second swab for detecting C trachomatis.     

Detection of Chlamydia trachomatis by ligase chain reaction compared with polymerase chain reaction and cell culture in urogenital specimens.

OBJECTIVE--The aim of this study was to evaluate the newly developed ligase chain reaction (LCR) assay for the detection of Chlamydia trachomatis in urogenital specimens using cell culture and Amplicor PCR for comparison. SUBJECTS--Two hundred and eighty patients attending hospital or urban STD clinics (high-risk population, 62 men and 84 women) and obstetric/gynaecology clinics (low-risk population, 134 women) in Bordeaux, France. METHODS--Specimens from men were tested with LCR on urethral swabs and urine, with Amplicor or urine, with cell culture on urethral swabs. Specimens from women were tested with LCR, Amplicor and cell culture on endocervical swabs and with LCR on urine. When the three methods generated different results, the LCR and Amplicor tests were repeated on the remaining samples. Samples with discordant LCR and Amplicor results and a negative culture were further analysed by major outer membrane protein gene omp1-PCR. RESULTS--After analysis of discrepant results, the overall prevalence was 7.5% (21/280) calculated on the basis of an expanded "gold standard" defined as culture positive or LCR plus Amplicor positive or omp1-PCR positive for discrepant results between LCR and Amplicor tests. Of the 21, 20 were detected by LCR, 17 by Amplicor and culture. The specificity of LCR and Amplicor was 99.6%. CONCLUSION--The LCR Chlamydia trachomatis test is a highly sensitive nonculture technique and a good alternative test for the detection of chlamydial infections.     

Detection of Chlamydia trachomatis antigen with an enzyme immunoassay

Urogenital swabs (571) were investigated with a solid-phase enzyme immunoassay for the detection of Chlamydia trachomatis antigen (Chlamydiazyme, Abbott). The results were compared with the conventional cell culture method (McCoy cell culture). Urogenital C. trachomatis infections were diagnosed with the cell culture in 14 of 122 male STD patients (12%), in 12 of 79 female STD patients (15%), in 23 of 89 prostitutes (26%), and in 3 of 115 asymptomatic males (3%). In comparison with cell culture, the sensitivity of Chlamydiazyme for urethral specimens from male STD patients was 86%. In female STD patients, for urethral specimens a sensitivity of 83% was found and for cervical specimens a sensitivity of 80%. The corresponding values for specimens from prostitutes were 60% and 100%, respectively. The specificity of Chlamydiazyme for urethral specimens of male STD patients reached 95%. With respect to urethral and cervical specimens of female STD patients, the specificity was 88% and 82%, respectively, and in prostitutes 92% each. The low specificity in female patients cannot be ascribed only to Chlamydiazyme since, after subcultivation and detection of inclusions by the use of fluorescein-labeled monoclonal antibodies, some of the false-positive Chlamydiazyme results turned out culture positive. This means that the specificity of Chlamydiazyme is actually higher. Because it can be performed rapidly and simply and reaches detection rates approaching those of the cell culture method, the enzyme immunoassay is an improvement in the diagnosis of C. trachomatis infections.     

Effects of broadening the gold standard on the performance of a chemiluminometric immunoassay to detect Chlamydia trachomatis antigens in centrifuged first void urine and urethral swab samples from men.

Traditionally, evaluations of nonculture assays for Chlamydia trachomatis are based on a comparison with urethral culture in men and cervical culture in women as the standard for positivity of infection, but it is known that culture may be less than 100% sensitive. A chemiluminometric immunoassay, Magic Lite (Ciba Corning, Medfield, MA) that detects C. trachomatis antigens was performed on centrifuged first void urine samples and urethral swabs collected from men attending a sexually transmitted disease (STD) clinic. Immunoassay performance was compared to urethral culture and also to a broader gold standard: an infected patient with positive culture results or a confirmed positive Chlamydiazyme enzyme immunoassay (Abbott, Chicago) result. Two studies were performed on a retrospective group of stored first void urine samples from 200 men and a prospective group of urethral swabs and first void urine samples from 199 men. Expanding the gold standard showed that a urethral swab assayed by culture had a sensitivity between 70.3% and 87.5%, with the following effects on immunoassay performance in the prospective study: the sensitivity of urethral swabbing was reduced from 96.2% to 78.4% (specificity increased from 96.0% to 98.1%) and first void urine sensitivity increased from 92.3% to 94.6% (specificity went from 87.9% to 93.8%). In the retrospective study, sensitivity of first void urine testing went from 91.4% to 92.5%, with a corresponding increase in specificity from 93.9% to 96.9%. This maneuver had relatively little impact on the negative predictive values, but dramatically increased the positive predictive values, for both samples.(ABSTRACT TRUNCATED AT 250 WORDS)     

连接酶链反应检测男性尿标本中沙眼衣原体

目的 评价连接酶链反应（LCR）检测男性尿标本中沙眼衣原体（CT）的敏感性和特异性。方法 取性病专科门诊162例男性就诊者尿道拭子作CT培养；同时取患者晨起或较长时间（2h以上）不排尿后的首次尿（FVU）标本，用质粒LCR检测CT。对培养和质粒LCR结果相异的标本，用另一针对CT主要外膜蛋白基因的LCR进行确证，参照“扩大的金标准”来确定检测结果。结果 质粒LCR检测的敏感性和特异性分别为100％和99．2％，而培养法分别为82．8％和100％。讨论 LCR是一种既敏感又特异的CT诊断方法。用尿标本作检测对象，可避免取尿道标本给患者带来的痛苦，可作为筛检男性CT感染的一种非损伤性方法。     

Unsatisfactory performance of the leukocyte esterase test of first voided urine for rapid diagnosis of urethritis.

BACKGROUND AND OBJECTIVES--The objective of this study was to determine the performance characteristics of a dipstick test for leukocyte esterase (LE), (Chemstrip 2LN, Boehringer Mannheim) in predicting the presence of urethritis and urethral pathogens in men presenting to a busy sexually transmitted disease clinic and to street outreach facilities. METHODS--Urethral swabs for polymorphonuclear (pmn) cell count, gonorrhoea culture and chlamydia enzyme immunoassay (EIA) as well as 15 ml of first voided urine (FVU) were collected from 737 symptomatic and 726 asymptomatic men. Gonorrhoea cultures and pmn counts were processed according to standard methods. Either Abbott Chlamydiazyme EIA (confirmed) or Syva Microtrak EIA (confirmed) test was employed to detect C trachomatis. The LE test was immediately dipped in FVU, read after 60-120 seconds by the clinician and considered positive if trace, 1+ or 2+. RESULTS--Microscopic evidence of urethritis (> or = = 4 pmn cells per 1000 x field) was found on urethral smear of 782 (53.5%) patients. Chlamydia, gonorrhoea or both were present in 104 (7.1%) patients. Performance characteristics of the LE test were as follows: (table below) CONCLUSION--The LE test did not have adequate sensitivity to be considered a reliable rapid diagnostic test for urethritis or urethral pathogens, particularly in the asymptomatic portion of this STD clinic population.     

Rapid diagnosis of Chlamydia trachomatis in male patients by antigen detection in urine samples.

To investigate the diagnostic value of testing urine samples as a rapid method for the detection of chlamydial antigen in males, first-catch urine (FCU) and urethral swab samples were obtained from 668 male patients and examined by an enzyme immunosorbent assay (EIA). Positive results were further analyzed by direct fluorescence antibody tests of the EIA sediment. Antigen detection was possible in 12.7% out of the urethra, in 10.8% out of FCU and in a total of 14.5% of the tested persons. Testing only FCU would have missed chlamydia detection in 25 (25.8%) out of a total of 97 chlamydia-positive males. Testing only genital samples would have missed 12 positive cases (12.4%). The sensitivity and specificity of the EIA test of FCU as compared with urethral swabs were 70.6 and 97.9%, respectively, and differed between urine collected before (sensitivity: 84%; specificity: 98.6%) and after (sensitivity: 65%; specificity: 97.7%; p = 0.1254) urethral sampling. The quantitative evaluation of the EIA results demonstrates that the mean value of the extinction rates was highest in specimens corresponding to a positive result from both sampling sites. This study indicates that the chlamydial detection rate was lower in FCU than in urethral samples. FCU testing may be suitable when urethral sampling is not possible; due to its high rate of unconfirmed borderline extinction, positive results should be confirmed with another chlamydial antigen detection test such as direct immunofluorescence.     

利用男性非淋菌性尿道炎患者尿沉渣检测沙眼衣原体

１０２例男性非淋菌性尿道炎患者，以尿道拭式沙眼衣原体培养为金标准，用ＷｅｌｌｃｏｚｙｍｅＣｈｌａｍｙｄｉａ检测清晨首次尿沉渣中沙眼衣原体的敏感性和特异性分别为８９．７％及９２．１％，用ＰＣＲ检测清晨首次尿沉渣中沙 眼衣原体敏感性和特异性分别为９７．４％及９２．１％。     

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.     

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.     

A comparison of an enzyme immunoassay and cell culture for detection of Chlamydia trachomatis in genito-urinary specimens

Chlamydia trachomatis infection is easy to treat but laborious to diagnose by culture. An antigen-detecting enzyme immunoassay (EIA; Chlamydiazyme, Abbott Laboratories, North Chicago, IL), suitable for testing many samples, was compared with the conventional iodine-stained, one-passage culture. A total of 471 duplicate samples from 218 men (urethra) and 128 women (urethra and cervix) attending a sexually transmitted disease clinic were examined by both tests. The overall sensitivity, specificity, and predictive value of positive and negative results were 80.3%, 96.7%, 86.4%, and 95.0%, respectively. No difference between male and female patients was observed. A remarkable difference between sensitivities of female urethral (60.0%) and cervical (95.5%) samples was found. This difference is clearly important in cases of women with urethral infection only (19% in our study) and points to the need for further improvement of this EIA.     

Comparison of the Amplicor Chlamydia trachomatis test and cell culture for the detection of urogenital chlamydial infections.

OBJECTIVE--To compare the polymerase chain reaction (PCR) Amplicor Chlamydia trachomatis test with the cell culture method, in diagnosing urogenital chlamydial infections. SUBJECTS--439 patients (327 women and 112 men) attending one STD clinic and Family Planning and Gynaecological Clinics in Lisbon, Portugal, between November 1993 and March 1994. METHODS--In women, two endocervical swab samples were collected: one for PCR Amplicor and one for standard culture technique. Men were asked to submit 20 ml of urine (first pass urine) for PCR Amplicor and one urethral specimen was taken for culture. The order of collection of the specimens was rotated every 50 patients. Discrepant results were further analysed by a second PCR with primers directed against the C trachomatis major outer membrane protein (MOMP) and by direct fluorescent antibody (DFA). RESULTS--After analysis of discrepancies, the adjusted sensitivity and specificity of PCR on endocervical specimens were 92.9% and 100% and the positive and negative predictive values were 100% and 99.7% respectively; on the urine samples these values were 100%, 99.1%, 100% and 99.1%, respectively. CONCLUSION--These results indicate that the PCR Amplicor test is a rapid sensitive and specific assay for the detection of C trachomatis in urogenital infections and provides a non-invasive technique for screening chlamydia infection in men.     

Use of Kova-Slide II with grid and uncentrifuged segmented urine specimens in the diagnosis of nongonococcal urethritis: a quantitative technique

An attempt was made to use uncentrifuged segmented urine specimens and Kova-Slide II with grid as a quantitative technique for the diagnosis of nongonococcal urethritis. Of the 100 men with urethral symptoms, 54 had fewer than five polymorphonuclear leukocytes per high-power field (x1000) in their gram-stained urethral smear. On the basis of examination of segmented urine and Kova-Slide test, 41 of these 54 patients were diagnosed as having nongonococcal urethritis. None of the 13 patients considered to be free of urethritis on the basis of segmented urine tests had a Chlamydia trachomatis--positive culture, and all became asymptomatic without treatment. All 46 patients who had more than five polymorphonuclear leukocytes per high-power field (x1000) also had positive segmented urine tests. The rate of isolation of C. trachomatis was similar for both groups of tests. This study revealed that patients with lower polymorphonuclear leukocyte counts in the first 10 ml of urine passed (voided-bladder urine 1) also had cultures positive for C. trachomatis. None of the 50 patients in the control group had polymorphonuclear leukocytes in either voided-bladder urine 1 or in the midstream specimen (voided-bladder urine 2). All controls had cultures negative for C. trachomatis.     

Multisite pooling study using ligase chain reaction in screening for genital Chlamydia trachomatis infections.

BACKGROUND: Ligase chain reaction (LCR), a nucleic acid amplification assay, is a highly specific and sensitive test for detecting Chlamydia trachomatis in cervical and urethral swabs as well as first-void urine specimens. GOAL: To examine the suitability of using the LCR test to detect C trachomatis in pooled cervical specimens. STUDY DESIGN: The performance of LCR in pooled specimens was compared with individual specimen testing at six laboratories using 3,170 cervical swab specimens randomly selected from specimens received for routine testing in the participating laboratories. These samples then were combined consecutively into 634 pools of 5 specimens and 317 pools of 10 specimens. A reduced sample to cutoff ratio of 0.2 or more was used for the pooled specimens. RESULTS: Of the 188 positive specimens (98.9%), 186 were identified when single specimens were analyzed. When pools of 5 or 10 specimens were evaluated, 99.5% and 98.9% of the positive swabs, respectively, were identified correctly. Two positive specimens were detected only through pooling. CONCLUSIONS: Pooling samples for detection of C trachomatis by LCR is sensitive and specific. Depending on the prevalence of infection (positivity), LCR testing may result in cost savings, as compared with individual testing of specimens.     

连接酶链反应检测性病患者沙眼衣原体感染

目的 评价连接酶链反应(LCR)诊断性病患者尿道/宫颈中沙眼衣原体(Ct)的意义。方法 STD门诊尿道(宫颈)炎患者276例,取尿道/宫颈拭子,以LCR分析法检测Ct。采用每4份标本相混合的方法分别以LCR分析法检测尿道/宫颈拭子标本中的Ct,其中56例患者同时进行尿道/宫颈拭子Ct细胞培养。差异性结果由PCR法扩增Ct的主要外膜蛋白基因来进行确认,确定LCR分析法检测Ct的敏感性、特异性。结果 LCR分析法检测尿道/宫颈拭子Ct的敏感性、特异性分别为96.7%和100%。采用每4份标本相混合的方法分别以LCR分析法检测尿道/宫颈拭子标本中的Ct,与单独用每份标本逐一进行LCR检测比较,结果完全一致,符合率为100%。结论 以尿道/宫颈拭子为标本,LCR分析法检测Ct的敏感性、特异性高。适用于诊断泌尿生殖道Ct感染。用标本相混合的方法LCR分析检测尿道/宫颈拭子标本中的Ct,适用于Ct感染的普查。     

四种检测泌尿生殖道沙眼衣原体方法的比较与评价

目的对胶体金免疫层析、酶免疫(EIA)、直接荧光抗体测定(DFA)和细胞培养四种检测泌尿生殖道沙眼衣原体的方法进行比较与评价。方法分别应用胶体金,EIA,DFA和细胞培养四种方法检测不同稀释倍数的沙眼衣原体E型标准株。35例临床疑为泌尿生殖道沙眼衣原体感染患者的宫颈或尿道拭子分别应用胶体金,EIA,DFA进行检测。结果能测出沙眼衣原体E型标准株为阳性的最大稀释倍数在胶体金,EIA,DFA和细胞培养法中分别为:104,106,108和104倍;35例临床标本的阳性率在胶体金,EIA和DFA法中分别为:11.43%,25.71%和40.00%,胶体金和DFA法之间差异有统计学意义(P<0.05),敏感性最高的为DFA法。结论 DFA法检测泌尿生殖道沙眼衣原体的敏感性较胶体金、EIA和细胞培养方法高,临床上可提倡应用。     

Asymptomatic Chlamydia trachomatis urethritis in men

Ten men with asymptomatic urethritis due to Chlamydia trachomatis were identified through culture screening and were treated with ceftriaxone (1 g given intramuscularly). Seven of the eight men who were followed for at least 21 days before and after therapy remained asymptomatic but culture-positive. One originally asymptomatic man had onset of symptomatic non-gonococcal urethritis 18 days after his first positive culture. Among asymptomatic men with positive cultures, pyuria was present in urine specimens obtained at 17 of 18 visits, while the leukocyte count on the urethral gram stain was above normal at ten of 29 visits (P less than .01). Therefore, one may conclude that ceftriaxone (1 g given intramuscularly) was ineffective therapy for chlamydial urethritis; male urethral infection with C. trachomatis can remain asymptomatic for 21-45 days; and in this population pyuria detected by urinalysis correlates better with infection than does a urethral gram stain.     

The value of urine specimens in screening for male urethritis and its microbial aetiologies in Tanzania.

OBJECTIVE--To evaluate the first void urine (FVU) specimen in screening for urethritis and its microbial aetiologies in a male African population in which urinary schistosomiasis is also prevalent. PATIENTS AND METHODS--Two hundred and forty eight males aged 15-54 years provided FVU specimens: 55 patients from a clinic for sexually transmitted diseases (STD), 151 patients from a medical outpatient clinic and 42 villagers from an area of high endemicity for S haematobium. Specimens were tested for leucocyte esterase (LE) using a dipstick (Nephur-Test+Leuco, Boehringer-Mannheim France SA). Ova of S haematobium were sought in terminal urine samples from all subjects. For all STD patients, and all medical outpatients with a positive LE test, urine and urethral swabs were tested for Chlamydia trachomatis antigen, and urethral swabs were tested for Neisseria gonorrhoeae by gram stain and isolation. RESULTS--The prevalence of LE positivity was 38/41 in STD patients with urethral signs or symptoms (93%), 5/14 among other STD patients (36%), 21/151 among medical outpatients (15%) and 13/42 among villagers (31%). As a screening test for urethral infection (detection of gonorrhoea or chlamydia and/or > or = 5 polymorphs per high power field on gram stain) the LE test had a sensitivity of 94% and a specificity of 53% among STD patients. Of 24 STD patients with gonococcal or chlamydial infection, 23 had a positive LE test (96%). Among general medical outpatients, 12 of 22 with a positive LE test had either conventionally defined urethritis or gonococcal or chlamydial infection, giving a positive predictive value of 55% for the LE test in this group. Of 18 subjects in all groups with urinary schistosomiasis nine had a positive LE test (50%), although three of these also had gonorrhoea. Chlamydial antigen was detected in the FVU specimen of all six subjects in whom it was detected in a urethral swab, and in an additional three subjects in the outpatient group. CONCLUSIONS--The FVU, which is an easily collected and non-invasive specimen, can provide valuable information on the prevalence of urethritis and on its microbial aetiology among the general male population in African countries.     

Cervical sampling for diagnosis of genital chlamydial infection with a new brush device.

OBJECTIVES--To compare a new sampling device, a brush, Accellone-Multi-Instrument (AMI), with a dacron-tipped swab for detection of Chlamydia trachomatis in endocervical specimens, and to evaluate if consecutive multiple cervical sampling as compared with such a single specimen would increase the sensitivity. METHODS--501 females attending an STD clinic and 172 females attending a family planning clinic were examined prospectively. Two cervical specimens were collected from each woman. C trachomatis were detected by culture or enzyme immunoassay (IDEIA-III). Positive EIA samples were confirmed by a direct immunofluorescent test. RESULTS--When cervical specimens were collected with the brush as the first device, 92% of the culture-positive cases were detected, and when the samples were collected with the dacron-tipped-swab first, 84% of the culture-positive cases were detected (p < 0.05). The first collected specimen detected 89% of the culture-positive cases and 81% of those that were positive by IDEIA. CONCLUSIONS--The study indicates that the AMI brush is superior to non-toxic, dacron-tipped swabs for detection of C trachomatis in cervical samples by cell culture but not by ELISA, and that the sensitivity could be improved by analysing multiple cervical samples.