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

Current concepts in bacterial sexually transmitted diseases

Sexually transmitted diseases (STDs) are the most common infectious diseases worldwide, with over 350 million new cases occurring each year, and have far-reaching health, social, and economic consequences. Failure to diagnose and treat STDs at an early stage may result in serious complications and sequelae. STDs are passed from person to person primarily by sexual contact and are classified into varied groups. Some cause mild, acute symptoms and some are life-threatening. They are caused by many different infectious organisms and are treated in different ways. Syphilis and gonorrhea are ancient afflictions. Now, however, Chlamydia is prevalent and has become the most common bacterial STD. Antimicrobial resistance of several sexually transmitted pathogens is increasing, rendering some regimens ineffective, adding to therapeutic problems. A standardized treatment protocol for STDs is recommended to ensure that all patients receive adequate treatment. Appropriate treatment of STDs is an important public health measure.

Optimal method of collection of first-void urine for diagnosis of Chlamydia trachomatis infection in men

First-void urine (FVU) is the preferred specimen for the diagnosis of urogenital Chlamydia trachomatis infection in men. We have developed FirstBurst, a urine collection device that collects the first 4 to 5 ml of FVU and yields a specimen with a sixfold higher C. trachomatis organism load than the regular urine cup by quantitative PCR (32,533 versus 5,271 plasmids/ml; P < 0.0001). Consequently, the use of FirstBurst to collect a urine sample improved the sensitivity of a rapid test for Chlamydia over testing of samples collected with a urine cup (82 versus 47% sensitivity using PCR as a reference; P < 0.0015).

Evaluation of Nucleic Acid Amplification Tests in the Absence of a Perfect Gold-Standard Test

During the past 10 years, medical diagnostic testing for sexually transmitted infections (STIs) has changed markedly as a result of the rapid expansion and marketing of nucleic acid amplification tests (NAATs). Among such new DNA/RNA-amplification techniques are the polymerase chain reaction (PCR), the ligase chain reaction (LCR), and the transcription-mediated amplification (TMA) tests. Regrettably, the test evaluation process undergone by these tests has not always been rigorous or scientifically sound. Here, we review the controversy surrounding the statistical evaluation of these NAATs. We also review some of the traditional and recent statistical methods developed to estimate test sensitivity and specificity parameters in the absence of reliable gold-standard tests. In particular, we review the traditional latent class modeling approach that requires the assumption of independence between diagnostic tests conditional on the true disease status, and the more recent procedures that relax the conditional independence assumption. Finally, we apply some of these statistical modeling techniques to real data to estimate the sensitivity and specificity of a NAAT for Chlamydia trachomatis. On the basis of the latent class modeling approach with a pessimistic prior for culture sensitivity, the NAAT specificity estimate was 97.6% and, on the basis of an optimistic prior, the specificity was 95.3%. Similarly, the sensitivity estimates ranged from 88.1% to 89.6%.

Ability of new APTIMA CT and APTIMA GC assays to detect Chlamydia trachomatis and Neisseria gonorrhoeae in male urine and urethral swabs

A clinical evaluation was conducted in six North American centers to determine the ability of APTIMA CT (ACT) and APTIMA GC (AGC) nucleic acid amplification assays to detect Chlamydia trachomatis and Neisseria gonorrhoeae infections in 1,322 men by testing their urethral swabs and first-catch urine (FCU). The results obtained with ACT and AGC assays were compared to an infected patient status determined by testing the specimens with the APTIMA Combo 2 and the BD ProbeTec energy transfer multiplex assays. Symptoms did not influence the values. Positive and negative agreements of the ACT and AGC assays for individual specimens were high, with each comparator assay ranging between 94.3 and 100% for positives and 93.9 and 99.4% for negatives. The ACT and AGC assays performed on noninvasive specimens such as FCU effectively identified C. trachomatis or N. gonorrhoeae infections in symptomatic and asymptomatic men and should be suitable for screening male populations.

Gender Differences in Bacterial STIs in Canada

HEALTH ISSUE: The incidence of bacterial sexually transmitted infections (STIs) is rising in Canada. If these curable infections were prevented and treated, serious long-term sequelae including infertility, and associated treatment costs, could be dramatically reduced. STIs pose a greater risk to women than men in many ways, and further gender differences exist in screening and diagnosis. KEY FINDINGS: Reported incidence rates of chlamydia, gonorrhea, and infectious syphilis declined until 1997, when the trend began to reverse. The reported rate of chlamydia is much higher among women than men, whereas the reverse is true for gonorrhea and infectious syphilis. Increases in high-risk sexual behaviour among men who have sex with men were observed after the introduction of potent HIV suppressive therapy in 1996, but behavioural changes in women await further research. DATA GAPS AND RECOMMENDATIONS: STI surveillance in Canada needs improvement. Reported rates underestimate the true incidence. Gender-specific behavioural changes must be monitored to enhance responsiveness to groups at highest risk, and more research is needed on effective strategies to promote safer sexual practices. Geographic and ethnic disparities, gaps, and needs must be addressed. Urine screening for chlamydia should be more widely available for women as well as men, particularly among high-risk men in order to prevent re-infections in their partners. As women are more likely to present for health examinations (e.g. Pap tests), these screening opportunities must be utilized. Female-controlled methods of STI prevention, such as safer topical microbicides, are urgently needed.

Developments in the screening for Chlamydia trachomatis: a review

Many studies have evaluated selective screening criteria for women in various settings. Most have concluded and all guidelines recommend that all women aged < 25 be screened yearly for C. trachomatis infection. Behavioral criteria, such as the number of sex partners, new or more than one sex partners, and previous infection, also can serve as criteria for screening women aged > 25. Because re-infection rates are high and occur within a few months, complications may be reduced further if partners are treated and women rescreened 4 to 6 months after initial infection. Revised recommendations for C. trachomatis screening programs have stated that more frequent screening may be considered among women < 20 and those with recent infection. Screening in nontraditional settings and careful evaluation of local prevalence and risk factor information should be encouraged. Private providers and emergency room providers should discuss screening recommendations and adopt a C. trachomatis screening policy for the population they serve. The HEDIS measure should serve to encourage at least annual screening of 15- to 25-year-old sexually active females through providers linked to managed care organizations. In general, high yields (ie, percentage of tests that are positive) in nontraditional settings and enhanced feasibility and acceptability of urine-based tests may encourage further innovative approaches to reach and screen populations at risk. Several issues remain to be addressed to increase the effectiveness of screening efforts. If more sensitive amplification tests are used widely, more infected persons will be identified and treated, and transmission patterns may change, particularly if partner treatment also occurs. Current screening criteria should continue to be re-evaluated. An important issue that affects testing methods includes the possible need for confirmation testing when using NAATs if the prevalence of C. trachomatis is less than 2%. If the sensitivity of an NAAT is 85% and specificity is 99%, in a hypothetical population of 10,000 with a prevalence of 2%, the positive predictive value is 170/268 (63%). A second important issue affecting testing methods and feasibility of using NAATs for screening large numbers of individuals is the pooling of urine specimens, which has been evaluated in several studies and found to be very effective for reducing costs. A research issue for pooling is the determination of the most cost-effective prevalence levels for pooling. An additional research question is in which populations should a NAAT be used for detection of C. trachomatis and N. gonorrhoeae. There are no recommendations for the routine screening of men because of the paucity of data showing that this strategy can reduce sequelae. The CDC is conducting a multisite study to examine the feasibility, acceptability, and usefulness of screening of asymptomatic men. There are a few studies have determining cost-effective prevalence threshold levels, particularly with NAATs. A recently developed decision analysis model by CDC designed to maximize the effectiveness of screening strategies for C. trachomatis infections may be useful for decision makers. It is intended to serve as an easy and flexible tool to determine cost effectiveness at a local level and takes into account positivity rates and test performance characteristics (SOCRATES). It is unclear if recurrent infection is caused by true re-infection by the same or a different partner or recurrence of initial infection. Recurrence may be caused by persistence of C. trachomatis or antibiotic resistance. This distinction is of scientific interest because the appropriate intervention differs (eg, identification of risk factors for the former and microbiologic investigations for the latter). Effective partner management and retesting are critical to reducing sequelae of C. trachomatis infection. Screening for C. trachomatis infection remains an essential component of C. trachomatis control. It is cost effective, most infections are asymptomatic, and symptom-based health care seeking and testing identify few of those infected. The likelihood that opportunities for screening are missed is high particularly in non-STD clinic settings. Local studies using NAATs to determine C. trachomatis prevalence and risk factors are helpful to health care providers so they can make evidence-based decisions on who to screen. The use of nontraditional, non-clinic-based test settings should be explored further. We have focused on summarizing the medical evidence regarding recommendations for screening for C. trachomatis. High-risk populations for C. trachomatis infection may overlap with populations for other STDs, and comprehensive STD prevention programs that involve a range of STD service providers are needed to successfully reduce the STD-related health burden in the population.

Update on the impact of Chlamydia trachomatis infection on male fertility

With approximately 90 million cases annually, infection with Chlamydia trachomatis is the most prevalent sexually transmitted bacterial disease in the world. Considering that these infections are often asymptomatic and cause major complications like acute pelvic inflammatory disease, ectopic pregnancy, infertility or infant pneumonia, the estimated costs for diagnosis and treatment in the USA amounts to 2.2 million US dollars for each 500 cases. Therefore, there is a high need for correct, quick and cost-effective diagnosis and treatment of this urogenital tract infection. New innovative therapies provide good results with regard to efficacy and patients' compliance. The success rates of treatments are at least 95%. However, the occurrence of antibiotic resistance should not be ignored and new treatment schemes must be developed. The state-of-the-art of diagnosis and treatment of chlamydial infections as well as the pathophysiology is discussed in this review. In conclusion, infections with C. trachomatis is an important public health problem, especially in third world and developing countries, and more socio-economic studies linking secondary prevention of chlamydial infections, infertility and adverse pregnancy outcome are needed to understand more of its aetiology. In addition, diagnosis and treatment should be improved. Data in men revealed that past infections but not present infections are more related to male infertility. There is still controversial results. In future studies, function of the seminal vesicles and evaluation of the antioxidant capacity should be taken into account when role of C. trachomatis infection on male fertility is assessed.

Acceptability of urine screening for Neisseria gonorrheae and Chlamydia trachomatis in adolescents at an urban emergency department

OBJECTIVE

The objective of this study was to determine the acceptability of urine screening for Neisseria gonorrhoeae and Chlamydia trachomatis in adolescents in a pediatric emergency department.

STUDY DESIGN

We used a prospective enrollment of adolescents aged 14-20 visiting an urban pediatric emergency department.

MAIN OUTCOME MEASURES

The main outcome measure was acceptance of urine STD screening rates.

RESULTS

Of 1231 potential participants, 879 (71%) agreed to participate and 352 (29%) declined screening. Participants were similar to those refusing to participate in terms of gender. In multivariate analysis, age, race/ethnicity, and insurance status were associated with variation in sexually transmitted disease (STD) test acceptance, whereas the presence of a parent was not. Despite similar training, 1 of 3 recruiters had significantly lower acceptance rates than her peers. Overall, 10% of patients enrolled were found to have one or both infections.

CONCLUSION

Urine screening for STDs can be efficiently conducted in an emergency department setting. This screening appears to be acceptable to most patients.

The impact of switching to polymerase chain reaction for the diagnosis of Chlamydia trachomatis infections in women

BACKGROUND

We noted a marked increase in Chlamydia trachomatis (CT) infections in the Capital Health Region of NS coincident with substitution of a PCR for an enzyme immunoassay (EIA). We reviewed our experience to determine the cost of switching and the impact on the number of new infections diagnosed.

METHODS

Information on the number of EIA and PCR tests performed on women was retrieved from an abstracted laboratory information database. We examined records of testing performed between April 1998 and December 2001. Prior to June 2001, all genital swabs were tested using the MicroTrak, II Chlamydia EIA and confirmed by direct fluorescence examination. After July 2001, genital swabs were tested using the COBAS AMPLICOR C. trachomatis test.

RESULTS

During the study period, 62,288 EIA tests were performed on specimens submitted; 2,061 (3.33%) were positive. In the six months when testing was performed by the PCR method, 9,559 PCR tests were performed, 463 (4.84%) were positive; 46% increase. In the three years before PCR testing was implemented, an average of 1,626 specimens were submitted monthly. An average of 54 tests were positive (3.3%). The cost for each positive detected by PCR was 208 dollars Cdn and 226 dollars by EIA.

CONCLUSIONS

The switch to PCR for the diagnosis of CT produced a marked increase in the number of chlamydia infections diagnosed. The recent increase in the number of reported CT cases in Canada may be due in large part to more sensitive tests. Surprisingly, the cost of each positive test by PCR was 18 dollars Cdn less than that of the EIA.

Efficacy of an RNA detection test kit in the diagnosis of genital chlamydial infection

A nucleic acid amplification method based on DNA detection, the current standard method for the diagnosis of genital infection by Chlamydia trachomatis, has been shown to potentially yield false-positive results after treatment in the clinical setting. RNA detection methods are more appropriate because viable organisms have multiple RNA copies that are surely detected by the method. In this study, we evaluated the efficacy of a new RNA detection test kit, the VIDAS PROBE CT test, in the diagnosis of genital chlamydial infection. For comparison, the standard DNA detection method, Amplicor STD-I, was also used in the study. First voided-urine samples and urethral smears from male patients with urethritis, and first voided-urine samples and cervical smears from female patients with cervicitis served as samples for the detection of C. trachomatis. Of the 60 first voided-urine samples from male patients, 21 were positive and 39 negative with the VIDAS PROBE CT test. Amplicor STD-I achieved exactly the same result. In female patients with cervicitis, the two test kits produced the same result, with 2 positive cervical smears and 38 negative. These results suggest that the VIDAS PROBE CT test is as efficient as Amplicor STD-I in the detection of C. trachomatis. While studies including a greater number of patients will be needed for revealing the unique advantages of the new RNA detection test kit, VIDAS PROBE CT, we concluded from the current study that the test may be clinically useful in the diagnosis of genital chlamydial infection.

Accuracy of results obtained by performing a second ligase chain reaction assay and PCR analysis on urine samples with positive or near-cutoff results in the LCx test for Chlamydia trachomatis

Nucleic acid amplification assays such as the ligase chain reaction and PCR have encountered reproducibility problems. The initial extract and a newly extracted aliquot of urine specimens (n = 120) which had signal-to-cutoff (S/CO) ratios above 0.80 by the LCx Chlamydia assay were retested. Nucleic acid was extracted from an additional urine sample for testing by the AMPLICOR PCR Chlamydia assay. Fifteen percent (18 of 120) of the urine specimens were negative by all repeat tests (initial mean S/CO ratio by the LCx Chlamydia assay, 0.93; S/CO ratio range, 0.80 to 3.30). Repeat testing of the 102 specimens with possible positive results by the LCx Chlamydia assay by use of the initially extracted aliquot confirmed the results for 95 (93.1%) of the specimens; repeat testing of a newly extracted aliquot confirmed the results for 87 (85.3%) of the specimens. Twenty specimens had discordant results by the two repeat LCx Chlamydia assays. A total of 78 of 102 (76.5%) of the specimens were positive by the AMPLICOR PCR, and the AMPLICOR PCR confirmed the results for 82.1% (78 of 95) and 89.6% (78 of 87) of the specimens positive by the two repeat LCx Chlamydia assays, respectively. Some of the discrepancies observed by multiple repeat tests may have been due to specimen mislabeling or contamination during performance of the procedure rather than to the LCx Chlamydia assay. Both assays suffered from a lack of reproducibility on repeat testing with a small proportion of specimens, probably due to the presence of low levels of DNA, the presence of variable amounts of amplification inhibitors, and the loss of DNA during extraction.

Risk behaviors, medical care, and chlamydial infection among young men in the United States

OBJECTIVES

This study assessed factors related to chlamydial infection among young men in the United States.

METHODS

Data were from interviews of nationally representative samples of 470 men aged 18 to 19 years (teenagers) and 995 men aged 22 to 26 years (young adults) and from urine specimens tested by means of polymerase chain reaction.

RESULTS

Although a majority of the men reported occasional unprotected intercourse, only a minority perceived themselves to be at risk for contracting a sexually transmitted disease (STD). Chlamydial infection was detected in 3.1% of the teenagers and 4.5% of the young adults. A minority of those infected had symptoms or had been tested for STDs; very few had been diagnosed with STDs.

CONCLUSIONS

Chlamydial infection is common but usually asymptomatic and undiagnosed. Primary and secondary prevention efforts should be increased, particularly among young adult men.

Prevalence of chlamydia and gonorrhoea among a population of men who have sex with men

OBJECTIVES

Few data are available on the prevalence of sexually transmitted diseases (STDs) in men who have sex with men (MSM), making it difficult to develop STD screening guidelines for this population. The objective of the study was to determine the prevalence of urethral infections caused by Chlamydia trachomatis and Neisseria gonorrhoeae within a large, community based population of MSM, and to assess the feasibility of rectal screening in this population.

METHODS

This was a cross sectional study of 566 MSM, who were predominantly middle aged, white, asymptomatic, and engaged in sex with multiple partners. All provided a urine sample to screen for chlamydial and gonorrhoea infections using a PCR assay; rectal screening was performed on 48 participants.

RESULTS

Urethral C. trachomatis infections were detected in 1/566 participants (prevalence 0.2%, 95% CI 0.004% to 1.0%), and rectal C. trachomatis infections were detected in 2/48 men (prevalence 4.2%, 95% CI 0.5% to 14.2%). No gonorrhoea infections were detected, and none of the 117 HIV positive men had either infection.

CONCLUSIONS

Chlamydial and gonorrhoea infections were uncommon in this sample of MSM, even among those with multiple sexual partners or HIV infection. These data call into question recommendations to screen all MSM based on their individual sexual behaviours or HIV. Additional data are needed on the prevalence of these infections in MSM from different settings.

PreservCyt transport medium used for the ThinPrep Pap test is a suitable medium for detection of Chlamydia trachomatis by the COBAS Amplicor CT/NG test: results of a preliminary study and future implications

The commercial COBAS Amplicor CT/NG test (Roche Diagnostic Systems, Meylan, France) is a sensitive and specific method for detection of Chlamydia trachomatis infections. This test currently consists of using a nucleic acid amplification method to detect C. trachomatis in first-void urine specimens and in endocervical swabs collected in 2-sucrose-phosphate (2SP) transport medium. We conducted a prospective study to determine whether the automated COBAS Amplicor CT/NG test can detect C. trachomatis in cervical specimens collected in PreservCyt transport medium (ThinPrep Pap Test; Cytyc Corporation, Boxborough, Mass.). PreservCyt medium is used to preserve cervical samples before the preparation of ThinPrep slides. We collected 1,000 cervical specimens from young women (age range, 15 to 25 years) during routine Pap smear tests. Only specimens with normal cytology and in which the gynecologist found no clinical evidence of urogenital infections were selected. The samples were stored in PreservCyt transport medium at 15 to 20 degrees C. C. trachomatis was detected in 22 of the 1,000 cervical specimens that had been stored in PreservCyt. To confirm the positive samples, the test was repeated on new endocervical swab specimens collected in 2SP transport medium. Only 9 of the 22 positive patients agreed to undergo this control, but all 9 retested positive. To evaluate the influence of storage conditions on the sensitivity of the C. trachomatis PCR test, all of the positive samples were stored at 15 to 20 degrees C in PreservCyt transport medium and were retested every 2 weeks for 6 weeks. C. trachomatis was successfully amplified from all 22 specimens for the whole 6-week period. The prevalence of C. trachomatis infection was 2.2% in our study population. These results demonstrate that PreservCyt transport medium is a suitable transport medium for detection of C. trachomatis by the COBAS Amplicor CT/NG test. The ThinPrep Pap Test may enable gynecologists to monitor for both cervical lesions and C. trachomatis infections with a single endocervical specimen.

The Use of Urine and Self-obtained Vaginal Swabs for the Diagnosis of Sexually Transmitted Diseases

Studies have reported that self-collected specimens, such as urine or vaginal swabs, can be successfully used to diagnose sexually transmitted infections when they are used with nucleic acid amplification assays. This eliminates the necessity for a clinician-performed pelvic examination for women, or a urethral swab for men, for sample collection. These nucleic acid amplification assays used with self-collected specimens are highly sensitive and specific, and their use may be extended to broad nonclinic screening venues, where their use can augment public health programs designed to control the epidemic of sexually transmitted diseases.

Urine-based screening for Chlamydia trachomatis in men attending sexually transmitted disease clinics

BACKGROUND

Nucleic acid-amplified tests for Chlamydia trachomatis are accurate but costly. Screening strategies for asymptomatic men are needed.

GOAL

To assess C trachomatis screening strategies for asymptomatic males.

STUDY DESIGN

Men attending a sexually transmitted disease clinic were tested for C trachomatis with ligase chain reaction and culture, and for urethral inflammation with urine leukocyte esterase and urethral Gram stain.

RESULTS

C trachomatis prevalence was 5.5% among 1,625 asymptomatic men. Ligase chain reaction increased detection by 49% among men without urethral inflammation. An age of younger than 25 years and urethral inflammation were associated with positive ligase chain reaction results. The negative predictive value of urine leukocyte esterase was highest among older men, but urethral Gram stain was equally sensitive in predicting infection regardless of age. An age of younger than 30 years or urethral inflammation identified the highest proportion of infections (92%) and reduced the percentage of men screened by 43%.

CONCLUSIONS

Urine ligase chain reaction increased C trachomatis detection, particularly among men without urethral inflammation. Testing all asymptomatic men younger than 30 years is optimal, whereas negative urine leukocyte esterase or urethral Gram stain results in men 30 years or older support no testing.

Screening for sexually transmitted diseases in human immunodeficiency virus-positive patients in Peru reveals an absence of Chlamydia trachomatis and identifies Trichomonas vaginalis in pharyngeal specimens

To determine the prevalence of sexually transmitted diseases (STDs), we screened 107 human immunodeficiency virus-positive patients in Peru, where the virus is predominantly sexually transmitted. Patients had multiple risk factors for STDs, and 38% of women and 50% of men had at least 1 STD (gonorrhea, trichomoniasis, herpes simplex, anogenital warts, or syphilis seropositivity). No chlamydial infection was detected, even though infection rates in the general population are 5%-12%. Patients receiving trimethoprim-sulfamethoxazole(TMP-SMZ) for prophylaxis or treatment of respiratory infections were least likely to have cervicitis and/or urethritis (odds ratio, 0.37; 95% confidence interval, 0.15-0.89). Although not optimal treatment, administration of TMP-SMZ is effective against chlamydial infection. We speculate that the use of concomitant medications, such as TMP-SMZ, may be inadvertently preventing chlamydial infection in this population. Another finding was the presence of Trichomonas vaginalis in pharyngeal specimens of 3 men with histories of orogenital activity. This has not been previously reported and requires further study.

Relationship of hormonal contraception and cervical ectopy as measured by computerized planimetry to chlamydial infection in adolescents

BACKGROUND

Adolescents are at increased risk for chlamydial infection and its sequelae. Hormonal contraception and cervical ectopy were previously suggested risk factors for chlamydia.

GOAL

To determine if chlamydia is more prevalent in female participants with greater ectopy and in hormonal contraceptive users.

STUDY DESIGN

Ninety-seven adolescent females aged 11 to 20 years were recruited from two Baltimore inner-city clinics. After administering a reproductive history questionnaire, endocervical specimens were tested for Chlamydia trachomatis by polymerase chain reaction. After acetic acid application to the cervix, cervical photographs were taken, the area of ectopy was quantified by computerized planimetry, and ectopy was categorized as none (0mm2), mild (< 22mm2), and moderate (> 22mm2). The likelihood of chlamydia by ectopy and type of hormonal contraceptive use was determined by logistic regression adjusted for age and sexual partners.

RESULTS

The odds of chlamydial infection was similar in persons with mild ectopy compared with no ectopy (adjusted odds ratio [OR], 0.76; 95% CI, 0.14-4.03), and in persons with moderate ectopy compared with no ectopy (adjusted OR, 1.94; 95% CI, 0.40-9.39). The likelihood of chlamydia was higher in depot-medroxyprogesterone acetate users compared with nonhormone users (adjusted OR, 5.44; 95% CI, 1.25-23.6). Oral contraceptive users did not have an increased likelihood of chlamydia (adjusted OR, 0.92; 95% CI, 0.10-8.78).

CONCLUSION

Using a new, reliable, and standardized technique to quantify cervical ectopy, the authors did not find an elevated prevalence of chlamydial infection in adolescents with cervical ectopy. Depot-medroxyprogesterone acetate use may increase the risk of chlamydial infection compared with combined estrogen-progestin oral contraceptives.

Opportunistic urine ligase chain reaction screening for sexually transmitted diseases in adolescents seeking care in an urban emergency department

STUDY OBJECTIVE

Neisseria gonorrhoeae and Chlamydia trachomatis are the most common bacterial sexually transmitted diseases (STDs) in sexually active youth and many infections are asymptomatic or unrecognized. This study used ligase chain reaction assays for determination of prevalence of gonococcal and chlamydial infections in adolescents seeking care at an urban emergency department.

METHODS

An unlinked prevalence study was performed with ligase chain reaction tests on voided urine specimens from a convenience sample of adolescents 14 years or older who sought care at the Children's Hospital of Alabama ED. Demographic data and data on care provided in the ED were determined from retrospective chart review of those patients whose urine specimens were tested.

RESULTS

Of 282 urine specimens screened, 13.5% (38) yielded positive findings on ligase chain reaction testing for either or both pathogens (20 [7%] positive for N gonorrhoeae, 23 [8%] positive for C trachomatis). In the context of acute care, gonorrhea or chlamydial infection was diagnosed in 5 (1.8%). STD prevalence did not vary significantly by age. Only 39% (15/38) of patients with infections detected by ligase chain reaction testing received potentially effective antibiotics as a result of their urgent care evaluation.

CONCLUSION

Many adolescents use the ED for nonurgent care and unsuspected STDs are often missed. Urine ligase chain reaction testing is a sensitive, noninvasive means of detecting STDs by which unsuspected adolescent STD cases can be detected in an ED setting.

Touchdown enzyme time release-PCR for detection and identification of Chlamydia trachomatis, C. pneumoniae, and C. psittaci using the 16S and 16S-23S spacer rRNA genes

Three touchdown enzyme time release (TETR)-PCR assays were used to amplify different DNA sequences in the variable regions of the 16S and 16S-23S spacer rRNA genes specific for Chlamydia trachomatis, Chlamydia pneumoniae, and Chlamydia psittaci as improved tests for sensitive diagnosis and rapid species differentiation. The TETR-PCR protocol used 60 cycles of amplification, which provided improved analytical sensitivity (0.004 to 0.063 inclusion-forming unit of Chlamydia species per PCR). The sensitivity of TETR-PCR with primer set CTR 70-CTR 71 was 96.7%, and the specificity was 99.6%, compared to those of the AMPLICOR PCR for the detection of C. trachomatis in vaginal swab samples. TETR-PCR for C. pneumoniae with primer set CPN 90-CPN 91 was 90% sensitive and 93.3% specific compared with a nested PCR with primer set CP1/2-CPC/D for clinical respiratory samples. TETR-PCR for C. psittaci with primer set CPS 100-CPS 101 showed substantial agreement with cell culturing (kappa, 0.78) for animal tissue samples. Primer sets were then combined into a single multiplex TETR-PCR test. The respective 315-, 195-, and 111-bp DNA target products were precisely amplified when DNA from each of the respective Chlamydia species or combinations of them was used. Multiplex chlamydia TETR-PCR correctly identified one strain of each of the 15 serovars of C. trachomatis, 22 isolates of C. pneumoniae, and 20 isolates of C. psittaci. The primer sets were specific for each species. No target products were amplified when DNA from C. pecorum or a variety of other microorganisms was tested for specificity. TETR-PCR with primers selected for specific sequences in the 16S and 16S-23S spacer rRNA genes is a valuable test that could be used either with individual primers or in a multiplex assay for the identification and differentiation of Chlamydia species from culture isolates or for the detection of chlamydiae in clinical samples.

Multicenter evaluation of the AMPLICOR and automated COBAS AMPLICOR CT/NG tests for detection of Chlamydia trachomatis

The fully automated COBAS AMPLICOR CT/NG and semiautomated AMPLICOR CT/NG tests were evaluated in a multicenter trial for the ability to detect Chlamydia trachomatis infections. Test performance compared to that of culture was evaluated for 2,236 matched endocervical swab and urine specimens obtained from women and for 1,940 matched urethral swab and urine specimens obtained from men. Culture-negative, PCR-positive specimens that tested positive in a direct fluorescent-antibody test or in a confirmatory PCR test for an alternative target sequence were resolved as true positives. The overall prevalences of chlamydia were 2.4% in women and 7.2% in men. The COBAS AMPLICOR and AMPLICOR formats yielded concordant results for 98.1% of the specimens. With the infected patient as the reference standard, the resolved sensitivities of COBAS AMPLICOR were 89.7% for endocervical swab specimens, 89.2% for female urine specimens, 88.6% for male urethral swab specimens, and 90.3% for male urine specimens. When results were analyzed as if only a single test had been performed on a single specimen type, the resolved sensitivity was always higher. The resolved specificities of PCR were 99.4% for endocervical swab specimens, 99.0% for female urine specimens, 98.7% for male urethral swab specimens, and 98.4% for male urine specimens. The internal control revealed that 2.4% of the specimens were inhibitory when initially tested. Nevertheless, valid results were obtained for 98.6% of the specimens because 59.1% of the inhibitory specimens were not inhibitory when a second aliquot was tested. The COBAS AMPLICOR and AMPLICOR CT/NG tests for C. trachomatis exhibited equally high sensitivity and specificity with both urogenital swab and urine specimens and thus are well suited for screening for C. trachomatis infection.

Detecting urethral and prostatic inflammation in patients with chronic prostatitis

OBJECTIVES

Diagnosis of urethral and prostatic inflammation can represent a challenge. We compare the accuracy of diagnostic methods for detecting inflammation in lower urinary specimens/samples.

METHODS

A standardized protocol was used to evaluate urethral smear, first-void urine (VB1), midstream urine (VB2), expressed prostatic secretions (EPS), and postmassage urine (VB3) in urologic patients with no symptoms or signs of urethritis who were attending our prostatitis clinic.

RESULTS

Of 235 subjects, 60 (26%) had leukocytes detected by the Gram-stained urethral smear, 44 (18%) by the VB1, and only 14 (6%) by the VB2. Compared with the urethral swab, VB1 had 0% to 22% sensitivity and 81% to 98% specificity, and VB2 had 8% to 11% sensitivity. Of 83 subjects with prostatic inflammation, the EPS detected 63 (76%) and the VB3 detected 68 (82%).

CONCLUSIONS

VB1 or VB2 examinations had low sensitivity for detecting urethral inflammation. Examining both the EPS and VB3 proved best for detecting prostatic fluid inflammation. Combining the urethral smear with lower urinary tract localization ("four-glass test") represents an optimal approach for detecting urethral and prostatic inflammation.

Multicenter evaluation of the fully automated COBAS AMPLICOR PCR test for detection of Chlamydia trachomatis in urogenital specimens

The fully automated COBAS AMPLICOR CT/NG test for the detection of Chlamydia trachomatis was evaluated in a multicenter trial. Test performance was evaluated for 2,014 endocervical swab and 1,278 urine specimens obtained from women and for 373 urethral swab and 254 urine specimens obtained from men. Culture served as the reference test. Culture-negative, COBAS AMPLICOR-positive specimens that tested positive in a confirmatory PCR test for an alternative target sequence within the C. trachomatis major outer membrane protein gene were resolved as true positives. The overall prevalence of chlamydia was 4.3% in cervical swabs and 11.0% in urethral swabs from men. When the results for each specimen type were considered separately, the resolved sensitivities were 96.5% (83 of 86) for endocervical swab specimens, 95.1% (39 of 41) for urine specimens from women, 100.0% (41 of 41) for urethral swab specimens from men, and 94.4% (17 of 18) for urine specimens from men; the resolved specificities were 99.4% (1,912 of 1,924) for endocervical swab specimens, 99.8% (1,204 of 1,207) for urine specimens from women, 98. 5% (325 of 330) for urethral swab specimens from men, and 100.0% (236 of 236) for urine specimens from men. For the subset of patients from whom both swab and urine specimens were collected, the combined results for both specimen types were used to identify all infected patients. Using these combined reslts as criteria, the resolved sensitivities for the COBAS AMPLICOR test were 82.6% (38 of 46) for endocervical swab specimens, 84.4% (38 of 45) for urine specimens from women, 84.2% (16 of 19) for urethral swab specimens from men, and 89.5% (17 of 19) for urine specimens from men. In comparison, the sensitivity of culture was only 56.5% (26 of 46) for endocervical specimens and 63.2% (12 of 19) for urethral specimens from men. The internal control provided in the COBAS AMPLICOR test revealed that 2.9% of specimens were inhibitory when they were initially tested. Nevertheless, valid results were obtained for 99. 1% of specimens because 68.7% of the inhibitory specimens were not inhibitory when a second aliquot of the original sample was tested. Two additional COBAS AMPLICOR-positive specimens were detected by retesting inhibitory specimens. The COBAS AMPLICOR CT/NG test for the detection of C. trachomatis exhibited equally high sensitivities and specificities with both urogenital swab and urine specimens and, thus, is well-suited for use in screening.

Urethritis. Diagnosis of nongonococcal urethritis

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

Noninvasive screening for genital chlamydial infections in asymptomatic men: Strategies and costs using a urine PCR assay

OBJECTIVE

To evaluate cost saving strategies to screen for genital chlamydial infection in men using polymerase chain reaction (PCR) technology.

METHODS

Men with no urethral symptoms presenting to a sexually transmitted disease (STD) clinic were recruited. Study participants underwent a questionnaire interview. Urethral swabs were taken to perform a smear for polymorphonuclear leucocytes (PMN) and for the detection of Chlamydia trachomatis by culture and PCR. First-catch urine was collected for a leukocyte esterase test (LET) and PCR.

RESULTS

C trachomatis infection was detected in 36 of 463 (7.8%) men. LET and PMN were positive in 10 (28%) and 12 (33%) infected men, respectively. Risk factors for chlamydial infection were younger than age 25 years, LET-positive, PMN-positive and STD contact (P<0.001). The direct cost of genital chlamydial infection in men in Canada has been previously estimated at $381/case. Based on a sensitivity of 90% for urine PCR, the estimated direct cost of testing all participants to detect 32 cases was $453/case. Using risk factors recommended in the Canadian STD Guidelines (age younger than 25 years, new partner, STD contact or unprotected sex), the same number of cases would have been detected by testing only 384 men at $376/case. Using age younger than 25 years or STD contact as the screening criterion, 78% of those infected would have been detected at $259/case, and no new cases would have been detected by adding LET-positive or PMN-positive as risk factors.

CONCLUSION

Targeted screening for chlamydial infection using urine PCR assay and risk factors recommended in the Canadian guidelines could substantially reduce the cost of screening at a STD clinic setting. LET and PMN smear did not appear to be useful indicators of chlamydial infection in this population.

Methods for the detection of male genital tract inflammation

Male genital tract inflammation is reflected by increased numbers of white blood cells (WBC) in semen. An ejaculate containing more than 10(6) WBC ml-1 semen is termed leukocytospermic. Among male infertility patients, the frequency of leukocytospermia is between 10% and 20%. By conventional light microscopy or sperm staining techniques, it is not possible to reliably differentiate WBC from immature germ cells in semen. In contrast, the cytochemical peroxidase method reliably identifies granulocytes, the most prevalent WBC type in semen. The method is cheap, fast and easy to perform. The gold standard for the detection of all WBC populations in semen is immunocytology using monoclonal antibodies. However, it is expensive and time-consuming, thus remaining a research tool at present. The measurement of granulocyte elastase in semen provides information on the number of granulocytes and their inflammatory activation. However, commercial granulocyte elastase enzyme immunoassays are expensive and due to logistical reasons often delay the results for more than 1 week. Leukocyte esterase dipstick tests lack both sensitivity and specificity for the detection of inflammatory changes in semen. For clinical purposes, the peroxidase method is ideally suited to detect inflammatory changes in semen.

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.

The inhibitory effect of phosphate on the ligase chain reaction used for detecting Chlamydia trachomatis

AIMS

To examine the detection limit of the ligase chain reaction kit for Chlamydia trachomatis, to study the inhibitory effect of phosphate on the ligase chain reaction, and to clarify the mechanism of inhibition.

METHODS

Three reference serovars of C trachomatis--D/UW-3/Cx, F/UW-6/Cx, and L2/434/Bu--were used to test the sensitivity of the chlamydia ligase chain reaction. Comparison was made of the inhibition by phosphate before and after DNA amplification. Phosphate in up to 2.4 mM concentration was added to specimens of C trachomatis serovar D (1 to 50 inclusion forming units (IFU)/reaction) before DNA amplification to examine the concentration dependency of phosphate inhibition of the ligase chain reaction.

RESULTS

The detection limits were 0.6 IFU/reaction for serovar D/UW-3/Cx and F/UW-6/Cx, and 0.4 IFU/reaction for L2/434/Bu. Phosphate inhibited the ligase chain reaction only when it was added before the amplification stage. The specimens containing chlamydia at 1 to 50 IFU/reaction were negative when the concentration of phosphate added at the prethermocycle stage was more than 1.2 mM.

CONCLUSIONS

Ligase chain reaction analysis is a reliable method of diagnosing C trachomatis infection because of its high sensitivity. It would be clearly superior to the currently used methods if the problem of inhibitors could be eliminated. The mechanism of inhibition of the ligase chain reaction by phosphate was thought to be blockade of the amplification of the target DNA. The efficacy of the ligase chain reaction could be inhibited by phosphate in the urine, so duplicate dilution analysis of some negative specimens should be useful.

Bias in discrepant analysis: when two wrongs don't make a right

Imperfect reference standards (alloyed standards) often hinder evaluation of new diagnostic tests. Discrepant analysis, a two-stage modification of the standard evaluation of diagnostic tests, has been used to circumvent this problem. In discrepant analysis, additional testing is performed to resolve discrepant results of the new diagnostic test and the alloyed standard. This article demonstrates algebraically that sensitivity and specificity will be overestimated by discrepant analysis, even when a perfect gold standard is used to resolve the discrepant results. The magnitude of the bias depends on the true sensitivity and specificity of the new test and initial alloyed standard, the prevalence of disease in the study population, and the proportion of concordant errors between the two tests. The article also demonstrates substantial bias associated with the use of alloyed standard tests in both stages of discrepant analysis. This procedure should not be used routinely for evaluation of diagnostic tests.

Pooling of urine specimens for PCR testing: a cost saving strategy for Chlamydia trachomatis control programmes

OBJECTIVES

To evaluate pooling of first catch urine (FCU) specimens as a cost effective strategy for chlamydia testing.

METHODS

Mock specimens were pooled with and without dilution to determine optimal pool size and ease of work flow. The performance of the Amplicor Chlamydia trachomatis PCR assay on pooled specimens was compared with individual testing using 370 FCU specimens from asymptomatic men presenting to an STD clinic. Cost savings associated with pooling were estimated.

RESULTS

Using mock specimens, the sensitivity and specificity of the Amplicor PCR assay were not affected by pool sizes of two and five, but at a pool size of 10 decreased sensitivity due to inhibition was observed in one of five mock pools when the pooling method which involved no dilution was used. Archived FCU specimens from a study of 370 asymptomatic men were combined consecutively into 74 pools of five and tested by PCR. Of the 18 pools that contained positive specimens, 17 were PCR positive. Compared with testing FCU specimens individually, pooling resulted in a sensitivity of 95%, specificity of 100%, and a cost savings of 57% based on reduced number of tests required.

CONCLUSION

Depending on the prevalence of infection, pooling of FCU specimens for PCR testing may result in cost savings compared with testing specimens individually. Further evaluations to validate this strategy using fresh FCU specimens are needed.

Detection of Chlamydia trachomatis by the Gen-Probe AMPLIFIED Chlamydia Trachomatis Assay (AMP CT) in urine specimens from men and women and endocervical specimens from women

Molecular biology-based amplification methods are significantly more sensitive than other methods for the detection of Chlamydia trachomatis. The performance characteristics of the new Gen-Probe AMPLIFIED Chlamydia Trachomatis Assay (AMP CT) with endocervical and urine specimens were compared to those of culture for patients attending two Baltimore City sexually transmitted disease clinics and a clinic for adolescents. AMP CT uses transcription-mediated amplification (TMA) and hybridization protection assay procedures to qualitatively detect C. trachomatis by targeting a 23S rRNA. Discrepant results between culture-negative and AMP CT-positive specimens were resolved by direct fluorescent-antibody staining of sedimented culture transport medium for elementary bodies and by TMA with 16S rRNA as a target. Following discrepant analysis, for 480 female urine specimens AMP CT had a sensitivity of 93.8% and a specificity of 100%. For 464 male urine specimens, the resolved sensitivity and specificity of AMP CT were 95.6 and 98.7%, respectively. For the 479 endocervical swab specimens the sensitivity of AMP CT was 100% and the specificity was 99.5%. Resolved culture sensitivities of AMP CT for female and male swab specimens were 52.3 and 58.9%, respectively. These results demonstrate that AMP CT is highly sensitive for the detection of C. trachomatis in endocervical specimens and in urine specimens from men and women.

Comparison of Roche Cobas Amplicor and Abbott LCx for the rapid detection of Chlamydia trachomatis in specimens from high-risk patients

OBJECTIVE

To evaluate two automated amplification systems for the detection of Chlamydia trachomatis in urogenital specimens, the Cobas Amplicor (Roche Diagnostic Systems, Branchburg, NJ) and the LCx (Abbott Laboratories, Abbott Park, IL).

STUDY DESIGN

The two systems were compared testing specimens from 302 high-risk patients, including 98 female cervical swab specimens and 204 male urine specimens. The patients attended the state STD clinic in Reykjavik, Iceland, either because of symptoms or as a result of contract tracing.

RESULTS

The prevalence of C. trachomatis infection was 15.3% in women and 13.2% in men. For the male urine specimens, the sensitivity and specificity were 100% and 99.4% for the Cobas Amplicor and 74.1% and 100% for the LCx. In the cervical swabs, both systems detected all 15 true-positive specimens. The internal control used with the Cobas Amplicor detected inhibition in 2% of the male urine and 20% female cervical swabs, respectively.

CONCLUSION

The Cobas Amplicor demonstrated slightly better sensitivity than LCx in male urine specimens. Both systems offer the benefits of automation for routine diagnostic testing.

Comparison of performance and cost-effectiveness of direct fluorescent-antibody, ligase chain reaction, and PCR assays for verification of chlamydial enzyme immunoassay results for populations with a low to moderate prevalence of Chlamydia trachomatis infection

Many laboratories use a commercial enzyme immunoassay (EIA) with verification testing to diagnose Chlamydia trachomatis infections in an effort to contain costs. This study was designed to compare the performance and cost-effectiveness of direct fluorescent-antibody assay (DFA), commercial PCR, and ligase chain reaction (LCR) for the verification of EIA results. Cervical specimens were screened by EIA. DFA, PCR, and LCR were compared as verification tests for EIA-reactive specimens and negative greyzone (NGZ) specimens at 50% below the cutoff value. These samples were also tested by in-house PCR, which was used in the analysis of verification results. A total of 477 (7%) of 6,571 samples were reactive or within the NGZ. EIA results with verification by DFA testing (EIA/DFA results) agreed with 93% of the true results compared with 97% for EIA/PCR results for one set of 242 samples; there was 97% agreement with true results for EIA/DFA results versus 95% for EIA/LCR results for another set of 235 samples. Ten samples were false positive by LCR. Time and costs were equivalent for EIA with the DFA, PCR, or LCR as the verification test but were two- to threefold greater for PCR or LCR alone than for EIA with verification. Since it is important to balance cost containment with public health objectives, DFA, PCR, and LCR as EIA verification tests for cervical samples offer acceptable sensitivities and specificities at reasonable cost for low- to moderate-risk populations and therefore can be extended to a broader spectrum of at-risk populations.

An internal control for routine diagnostic PCR: design, properties, and effect on clinical performance

We constructed internal controls (ICs) to provide assurance that clinical specimens are successfully amplified and detected. The IC nucleic acids contain primer binding regions identical to those of the target sequence and contain a unique probe binding region that differentiates the IC from amplified target nucleic acid. Because only 20 copies of the IC are introduced into each test sample, a positive IC signal indicates that amplification was sufficient to generate a positive signal from targets present at the limit of test sensitivity. The COBAS AMPLICOR Chlamydia trachomatis, Neisseria gonorrhoeae, Mycobacterium tuberculosis, and human hepatitis C virus tests exhibited inhibition rates ranging from 5 to 9%. Approximately 64% of these inhibitory specimens were not inhibitory when a second aliquot was tested. Because repeatedly inhibitory specimens were not reported as false negative and because additional infected specimens were detected during retesting, test sensitivities were 1 to 6% greater than they would have been if the IC had not been used.

Detection of male genital infection with Chlamydia trachomatis and Neisseria gonorrhoeae using an automated multiplex PCR system (Cobas Amplicor)

We evaluated Cobas Amplicor, a highly automated polymerase chain reaction (PCR) system, to test first-void urine (FVU) and urethral swab specimens for Chlamydia trachomatis and Neisseria gonorrhoeae in men attending a sexually transmitted infection (STI) clinic. Results were compared against an in-house radioimmune dot blot (DB) test for C. trachomatis and selective culture for N. gonorrhoeae. Three hundred and ninety sets of specimens were obtained from 378 consecutive new and returned-new patients. Gonorrhoea prevalence was 9.49%, with no significant difference in sensitivity or specificity between culture and PCR. Chlamydia prevalence was 15.4%, with sensitivities of: DB 55%, PCR of FVU 86.7%, urethral swab PCR 90%. The specificity of PCR on FVU and urethral swabs was 100%. We have shown that Cobas Amplicor PCR is highly sensitive and specific in the diagnosis of chlamydia and gonorrhoea in men attending an STI clinic. Further economic and scientific studies are needed to determine the cost-effectiveness of this technique for screening in primary care settings.

Influence of endocervical specimen adequacy on PCR and direct fluorescent-antibody staining for detection of Chlamydia trachomatis infections

The cellular quality of the endocervical swab specimen used for the detection of Chlamydia trachomatis may dramatically impact the sensitivity of the diagnostic assay used. An evaluation of the adequacy of 319 endocervical swab specimens from women attending two inner-city sexually transmitted disease and family planning clinics, as well as five high school-based family planning clinics, was performed, and the resulting data were compared with the diagnostic results obtained by both Amplicor PCR and Microtrak direct fluorescent-antibody (DFA) staining. The swab from each patient was rolled across the open circular area of a DFA slide and then used to inoculate a transport tube for PCR (Roche), after which the swab was discarded. The slides were stained and examined by epifluorescence microscopy for the presence of C. trachomatis elementary bodies and for the presence and number of cell types to determine specimen adequacy. Cellular adequacy for a cervical swab specimen was defined as the presence of one or more columnar epithelial or metaplastic epithelial cells or the presence of more than 100 erythrocytes per high-power microscopic field. Of the 319 specimens read by DFA, 204 (63.9%) were determined to be adequate. There were 34 (10.7%) positive specimens by DFA and/or PCR. Twenty-nine (9.1%) specimens were positive by PCR, 20 (6.3%) specimens were DFA positive, and 15 (4.7%) were concordantly positive by both tests. The prevalence of chlamydia among adequate specimens was 14.2% (29/204), compared to 4.3% (5/115) for inadequate specimens (P < 0.0001). Variations in specimen quality and the sensitivity of the diagnostic assay used have a significant impact on determining the prevalence of C. trachomatis in a population.

Comparison of three commercially available amplification assays, AMP CT, LCx, and COBAS AMPLICOR, for detection of Chlamydia trachomatis in first-void urine

We compared the Gen-Probe transcription-mediated amplification assay (AMP CT), the Abbott LCx assay, and the Roche COBAS AMPLICOR assay for the detection of Chlamydia trachomatis in a mixed population in urine samples. First-void urine, urethral specimens, and cervical specimens in females were obtained from 1,000 patients (544 males and 456 females) visiting the outpatient sexually transmitted disease clinic of our hospital. The prevalence of C. trachomatis infection was 7.7% as determined by tissue culture of urethral and cervical specimens. The sensitivities of LCx, COBAS AMPLICOR, and AMP CT compared to cell culture were 79, 86, and 78%, respectively. Sensitivity and specificity were recalculated by using a new "gold standard", i.e., a sample was considered to be true positive if two or more techniques yielded positive results. Specimens positive only by cell culture or positive in only one commercial amplification technique were retested by a previously described in-house PCR. After discordance analysis the sensitivities of LCx, COBAS AMPLICOR, and AMP CT were 84, 93, and 85%, respectively. Specificity exceeded 99% for all three assays. With each method the sensitivity was lower for urine samples from females compared to urine samples from males. By application of this new gold standard, existing differences between methods are highlighted; future evaluations of new techniques should be validated against two or more amplification assays.

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.

Chlamydia trachomatis genital infection

OBJECTIVE

To determine family physicians' approaches to detecting, managing, and preventing genital Chlamydia trachomatis infection and their perceptions of barriers to prevention. To determine whether sex of physician is associated with differences in clinical approach to chlamydia, with levels of effort aimed at its prevention, and with perceived barriers to preventive efforts.

DESIGN

Questionnaires were sent to a random sample of family physicians.

SETTING

All health regions in Nova Scotia.

PARTICIPANTS

Two hundred fifty-seven Nova Scotia family physicians.

MAIN OUTCOME MEASURES

Responses to survey questions analyzed for association of practice behaviours with sex of physician.

RESULTS

Response rate was 60%. Most physicians performed diagnostic tests for chlamydia on all patients. Responses indicated that 17% would test for C trachomatis during an annual Papanicolaou test in a low-risk 30-year-old, 61% would test a high-risk 21-year-old man, and 89% would test a pregnant 17-year-old. Therapies physicians might use were judged appropriate in 96% of responses. Only 51% indicated they would ever discuss false-positive test results with patients. Men physicians were less likely than women to ask 75% or more of their adolescent patients about sexual activity or to educate them about prevention of sexually transmitted diseases. Women physicians saw time and the fee schedule as less serious barriers to prevention than men did.

CONCLUSIONS

Some physicians are not managing C trachomatis well. We should explore situations where gaps in performance are associated with sex of physician.

Risk factors for urethritis in heterosexual men. The role of fellatio and other sexual practices

BACKGROUND

Nonchlamydial nongonococcal urethritis (NGU) is a common sexually transmitted disease (STD) in heterosexual men. Prior studies have suggested that NGU may be acquired by insertive oral sex.

GOAL

To assess the association of oral sex and other sexual practices with nonchlamydial NGU in heterosexual men in order to better understand this syndrome and to guide its prevention and treatment. Risk factors for urethral gonorrhea and chlamydial infection were explored to contrast with NGU.

STUDY DESIGN

A retrospective case-control study was conducted among heterosexual men attending as STD clinic during 1993 and 1994. The study included 4,848 men who were sexually active within the prior 2 months and had urethral specimens obtained for Gram's stain, culture for Neisseria gonorrhoeae, and culture for Chlamydia trachomatis.

RESULTS

Insertive oral sex was not shown to be an independent risk factor for NGU. Independent predictors of nonchlamydial NGU by multivariate analysis included African-American race (odds ratio [OR] 3.71, 95% confidence interval [95% CI] 3.06 to 4.50) and having > or = two sex partners in the prior 2 months (OR 1.45, 95% CI 1.20 to 1.75). History of using condoms "always" was negatively associated with NGU (OR 0.59, 95% CI 0.43 to 0.79), gonorrhea (OR 0.31, 95% CI 0.17 to 0.56), and chlamydial infection (OR 0.67, 95% CI 0.44 to 1.03).

CONCLUSIONS

This study supports the sexually transmitted nature of nonchlamydial NGU but did not confirm an association with oral sex. However, the analysis was compromised by the rarity of insertive oral sex as patients' only sexual exposure. Consistent condom use protects against all causes of sexually acquired urethritis.

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

OBJECTIVE

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

DESIGN

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

RESULT(S)

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

CONCLUSION(S)

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

High prevalence of Chlamydia trachomatis infections in adolescent females not having pelvic examinations: utility of PCR-based urine screening in urban adolescent clinic setting

PURPOSE

To determine utility of polymerase chain reaction (PCR)-based urine screening for Chlamydia trachomatis in the care of adolescent females in an urban clinic.

METHODS

Females > or = 15 years of age attending an adolescent clinic were approached consecutively. Each enrollee was interviewed to determine the primary reason(s) for the clinic visit and was queried about genitourinary symptoms. Nonsterile voided urine specimens were tested for C. trachomatis using PCR-based analysis. Endocervical C. trachomatis cultures were obtained from the subjects who had a pelvic examination. Main outcome measures were chlamydia infection rates in clinic attendees whether a pelvic examination was performed or not.

RESULTS

A total of 315 (99.4%) of 317 patients approached agreed to participate. Overall, 47 (14.9%) patients had positive urine PCR tests. The chlamydia infection rate detected by urine PCR was 22.1% (19 of 86) among those who had pelvic examinations performed and 12.2% (28 of 229) among those who did not (p = .03; odds ratio 2.04; 95% confidence interval 1.02, 4.06). Sixty percent (28 of 47) of chlamydia infections identified during the study period were identified by the urine screening test.

CONCLUSION

Urine screening was accepted by vast majority of female adolescents attending the clinic irrespective of reason for the clinic visit, and was highly effective in identifying unsuspected C. trachomatis infections, particularly among girls attending the clinic for reasons unrelated to reproductive health care and as an interim screening tool for adolescent family-planning clients.

Diagnosis of Neisseria gonorrhoeae infections in women by using the ligase chain reaction on patient-obtained vaginal swabs

The increased sensitivities of nucleic acid amplification tests such as ligase chain reaction (LCR) have the potential to simplify specimen collection for gonorrhea diagnosis. In this study patients took their own vaginal swab specimens for gonorrhea culture and LCR testing. Immediately following specimen collection by patients, a trained clinician obtained endocervical swab specimens for the same tests. By using LCR to diagnose gonorrhea, 54 (17.5%) of 309 patients had positive tests. Forty-five patients with positive cervical LCR tests also had positive vaginal LCR tests; for one patient, only a cervical LCR specimen was positive, and for eight patients, only vaginal specimens were positive. For specimens from patients whose gonorrhea cultures were positive, all vaginal swab specimens were positive by LCR and 42 (91%) of 46 cervical swab specimens were positive by LCR. LCR-positive specimens from eight patients with negative cultures (four with positive vaginal specimens only, one with a positive cervical specimen only, and three with positive vaginal and cervical specimens) were further evaluated with unrelated probe sets for gonococcal pilin B. Following resolution of the discrepancies between culture-negative and LCR-positive specimens, a diagnosis of gonorrhea could be confirmed for 52 of 54 patients with positive LCR tests. LCR testing with vaginal swabs was 100% sensitive and 99.6% specific and had a positive predictive value of 98.1% and a negative predictive value of 100%. In this study LCR testing of vaginal swab specimens obtained by patients themselves was significantly more sensitive for gonorrhea diagnosis of women than cervical LCR or culture (100% versus 84.6% for cervical LCR or culture; Mantel-Haenszel chi-square test result, 8.58; P = 0.003).

Feasibility and yield of screening urine for Chlamydia trachomatis by polymerase chain reaction among high-risk male youth in field-based and other nonclinic settings. A new strategy for sexually transmitted disease control

BACKGROUND

Inner-city youth are at disproportionate risk for Chlamydia trachomatis infection. Identification of infected individuals is hampered by the often asymptomatic nature of infection and access and utilization barriers to clinic-based screening services. The feasibility and yield of screening urine for C. trachomatis by polymerase chain reaction was studied among high-risk male youth outside traditional clinic settings.

METHODS

As part of a community-level sexually transmitted disease (STD) prevention program among high-risk youth in Denver, outreach workers enrolled subjects, administered questionnaires, and collected first-catch urine samples in nonclinical facility-based and field-based settings. Facility settings consisted of community/recreation centers, high-schools, and an STD/human immunodeficiency virus prevention storefront. Field settings included alleys, parking lots, parks, and residences. Individuals who tested C. trachomatis positive were contacted by program outreach workers and provided with standard treatment and partner notification services.

RESULTS

Over a 20-month period, 486 urine specimens were collected, 32 (6.6%) of which were C. trachomatis positive. Rates were higher for subjects screened in the field than in facility settings (11.9% vs. 4.4%, P < 0.05). Subjects with chlamydial infection were more likely to have had vaginal intercourse in the previous 30 days (adjusted odds ratio: 2.9) and to have been recruited in field settings (adjusted odds ratio: 2.5). Of subjects with chlamydial infection, 31/32 (97%) were treated within a median of 8 days after urine collection.

CONCLUSIONS

Urine chlamydial screening by polymerase chain reaction of sexually active male youth in nontraditional settings appears to be feasible and to provide yields similar to those reported in standard clinic settings. Evaluation of samples easily collected in nonclinic locations holds great promise as an additional strategy for the control of chlamydial infection and other STD among difficult-to-reach populations.

Diagnosis of genitourinary Chlamydia trachomatis infections by using the ligase chain reaction on patient-obtained vaginal swabs

We compared the ligase chain reaction (LCR) assay to cell culture for diagnosis of genitourinary chlamydial infections in women using swab specimens obtained by clinicians from the endocervix and by patients from their own vaginas. Specimens from 40 (12.9%) of 309 patients were positive for chlamydial infection by culture, while the specimens of 50 (16.2%) patients were positive by LCR. Chlamydia trachomatis infection was verified for 9 of 10 patients whose LCR specimens were positive but whose cultures were negative. Vaginal and cervical swab specimens were positive by LCR for 46 (93.9%) and 44 (89.8%) of 49 chlamydia-infected patients, respectively. These data suggest that LCR testing for chlamydia with vaginal swab specimens obtained by patients themselves is as sensitive as cervical LCR and more sensitive than cell culture.

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.