Noninvasive tests for diagnosis of Chlamydia trachomatis infection: application of ligase chain reaction to first-catch urine specimens of women

Detection of Chlamydia trachomatis infections by polymerase chain reaction in asymptomatic pregnant women with special reference to the utility of the pooling of urine specimens

BACKGROUND & OBJECTIVES

Genital Chlamydia trachomatis (CT) infections are one of the most prevalent sexually transmitted infections across the world. In pregnant women, if not detected and treated early, these may result in poor pregnancy outcomes and complications. The present study was aimed to screen CT infections from first void urine (FVU) samples of asymptomatic pregnant women using molecular methods. The secondary objective was to evaluate cost-effectiveness in pooling FVU samples for their diagnostic application.

METHODS

FVU samples were collected from 1000 asymptomatic pregnant women over a period of three years. Pooling was done by including five specimens in one pool in the amount of 10 μl and subjected to polymerase chain reaction (PCR) and further confirmed by direct fluorescent antibody assay (DFA).

RESULTS

The age of study participants ranged from 18 to 43 yr with the median±standard deviation of 26±3.84 yr. Majority of positive participants were younger than 25 years. A total of 200 pools were prepared and 20 of these were PCR positive. When individual specimen in 20 positive pools was tested, 20 PCR-positive specimens were identified from 19 pools, of which 16 were positive by DFA. Thus, CT was detected in 1.6 per cent asymptomatic pregnant women in India and pooling strategy resulted in 70 per cent reduction in a number of tests performed.

INTERPRETATION & CONCLUSIONS

Our study detected C. trachomatis infection in 1.6 per cent asymptomatic pregnant women, and pooling of FVU specimens for PCR testing was found to be a cost-saving strategy in comparison to testing individual samples. Further evaluation and studies on the bigger sample size are warranted to validate these results.

Should asymptomatic men be included in chlamydia screening programs? Cost-effectiveness of chlamydia screening among male and female entrants to a national job training program

OBJECTIVE

To compare the cost-effectiveness of various chlamydia screening strategies within a population of male and female youth entering a national job training program.

STUDY DESIGN

Cost-effectiveness analysis of various chlamydia screening strategies among a cohort of 4000 female and male New England job training students. Strategies for women include (a) no screening, (b) universal endocervical DNA probe screening, (c) universal urine based NAAT screening, and (d) universal endocervical NAAT screening. Strategies for men include (a) no screening, (b) selective urine NAAT screening of leukocyte esterase (LE)-positive urines, and (c) universal urine-based NAAT screening.

RESULTS

Universal endocervical NAAT screening of women and universal urine NAAT screening of men were the most effective and cost-effective strategies individually and in combination. Endocervical NAAT screening of women prevented 23 more cases of PID and saved $27,000 more than endocervical DNA probe screening. Likewise, universal urine NAAT screening of men prevented 21 more cases of PID in their female partners and saved $16,000 more than selective urine NAAT screening of LE positive men.

CONCLUSIONS

Use of a sensitive NAAT to screen both men and women for chlamydia upon entry to a National Job Training Program is cost-effective, cost-saving, and provides a public health opportunity to substantially reduce chlamydia infections among youth at risk for sexually transmitted diseases.

Which test is best for chlamydia?

Nucleic acid amplification tests are now the tests of choice for diagnosing Chlamydia trachomatis infection. For the first time there are diagnostic tests for Chlamydia trachomatis that are more sensitive than tissue culture. Another major advantage is that they can be used with first-catch urine specimens and vaginal swabs. It is thus possible to test for genital chlamydial infection without using invasive specimen collection methods.

Diagnosis of Chlamydia trachomatis in Russia ? in-house PCR assays may be effective but overall optimization and quality assurance are urgently needed

In the present study, the performance of the cell culture method, two non-Russian direct immunofluorescence (DIF) assays, and three different in-house polymerase chain reaction (PCR) tests used in St. Petersburg, Russia, for detection of Chlamydia trachomatis in urogenital specimens was evaluated. A total of 650 patients were examined and it was most disquieting that previous C. trachomatis positivity with Russian DIF assays could - 7 days later - be confirmed only in 26% of the women and 30% of the men. Overall, the highest diagnostic sensitivity was obtained using PCR analysis. However, the sensitivity varied significantly: from 79% to 100% between the different PCR assays, sex of the patients, and type of samples. The highest sensitivity was obtained for female vaginal and male urine samples (100%). The specificity of the PCR assays varied from 97% to 100%. The sensitivity of cell culture and both the examined DIF assays was low, i.e. it varied from 46% to 56% and 55% to 75%, respectively. Meanwhile, cell culture was 100% specific and the DIFs showed a specificity varying from 99% to 100%. In conclusion, in a Russian perspective, adequate in-house PCR methods may be used quite effectively for detection of C. trachomatis in invasive as well as non-invasive clinical material. Simultaneous analysis of two different specimens from women resulted in a significantly increased detection rate of C. trachomatis. Nevertheless, in Russia the need for optimization and quality assurance of diagnostic methods for C. trachomatis, especially Russian DIF assays, has to be emphasized.

High analytical sensitivity and low rates of inhibition may contribute to detection of Chlamydia trachomatis in significantly more women by the APTIMA Combo 2 assay

The clinical sensitivity of nucleic acid amplification tests may be determined by analytical sensitivity and inhibitors in patient samples. We established endpoints for detection of propagated Chlamydia trachomatis L2 434, diluted according to swab and urine protocols for APTIMA Combo 2 (AC2), ProbeTec ET (PT), and Amplicor (AMP) assays. AC2 was 1,000-fold more sensitive than PT and 10-fold more sensitive than AMP on mock swab specimens. For urine, AC2 analytical sensitivity was 100-fold greater than those of the other assays. Spiking an aliquot of each clinical-trial sample from 298 women demonstrated inhibition rates in first-void urine (FVU), cervical swabs (CS), and vaginal swabs (VS) of 12.1%, 12.8%, and 10.4% for AMP; 27.2%, 2%, and 2%, for PT; and 0.3%, 1.7%, and 1.3% for AC2. Inhibition of our C. trachomatis spike and the PT or AMP amplification controls from the manufacturers showed less than 50% correlation. Using an infected-patient reference standard (a specimen positive in at least two tests or a single test positive in two of three samples) in AC2, the VS identified 68/69 (98.6%) infected women compared to CS (89.9%) or FVU (81.2%). Significantly fewer women were identified by PT (65.2%, 63.8%, and 66.7%) or AMP (65.2%, 59.4%, and 56.5%) with the three specimens. By individual specimen type, AC2 confirmed virtually all PT- and AMP-positive specimens, but rates of AC2 confirmation by AMP or PT ranged from 62.9 to 80.3%. The AC2 test identified significantly more women infected with C. trachomatis (P = 0.001). Vaginal swabs appear to be the specimen of choice for screening.

Interventions and Patterns of Risk in Adolescent HIV/AIDS Prevention

Mid-way through the third decade of experience in preventing HIV/AIDS among adolescents, behavioral interventions and outcomes for high risk subgroups have generated evidence extremely instructive for navigating future priorities in reducing transmission risk behavior. Youth who abuse alcohol or drugs, who are detained or incarcerated, or have mental health co-morbidity such as externalizing disorders, represent the most significant challenge to current and future efforts to control the epidemic among the adolescent population. Although there is no unambiguous, standard intervention approach with adolescents, patterns of risks and outcomes with these subgroups are instructive in the critical priority of creating more sustainable gains with our HIV prevention resources. This article provides a synthesis of the evidence with these subgroups, discusses important limitations and difficulties in the current intervention science and highlights promising directions for the next generation of effort in reducing adolescent HIV-related sexual risk behavior. Because individual-level interventions have had only modest effects, a key current emphasis within the field is to develop multilevel interventions with a more ecological or contextual focus. We review various pragmatic responses that acknowledge this priority and the debt owed to individual-level intervention work with adolescents.

Vaginal swabs are the specimens of choice when screening for Chlamydia trachomatis and Neisseria gonorrhoeae: results from a multicenter evaluation of the APTIMA assays for both infections

BACKGROUND

Vaginal swabs were recently U.S. Food and Drug Administration-cleared for detecting Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (GC) using Gen-Probe Incorporated's APTIMA COMBO2 Assay (AC2). We assessed the APTIMA CT Assay (ACT) for CT, APTIMA GC Assay (AGC) for GC, and AC2 for both organisms using patient- and clinician-collected vaginal swabs.

METHOD

Women attending family planning, obstetrics and gynecology, or sexually transmitted disease (STD) clinics had first-catch urines (FCUs), patient-collected vaginal swabs, clinician-collected vaginal swabs, and endocervical swabs tested by ACT, AGC, and AC2. A second endocervical swab and FCU were tested using BD ProbeTec (Becton Dickinson) for CT and GC. We calculated sensitivity and specificity using vaginal swabs to detect CT and GC.

RESULTS

Of 1,464 subjects enrolled, 180 had CT and 78 GC. ACT sensitivities and specificities for patient-collected vaginal swabs were 98.3% and 96.5%, respectively; for clinician-collected vaginal swabs, 97.2% and 95.2%, respectively. AGC sensitivities and specificities for patient-collected vaginal swabs were 96.1% and 99.3%, respectively; for clinician-collected vaginal swabs, 96.2% and 99.3%, respectively. AC2 results were similar. If an FCU tested positive for CT or GC, >94% of matching vaginal swabs were positive. Positive endocervical swabs showed slightly less concordance (>90% and >88%, respectively). More infected patients were identified using vaginal swabs than FCUs. With AC2, 171 CT-infected patients were identified using FCUs and 196 using patient-collected vaginal swabs. This difference was more pronounced for CT than for GC.

CONCLUSIONS

Vaginal swab specimens allowed sensitive and specific detection of CT and GC in the APTIMA assays. Vaginal swabs identified as many infected patients as endocervical swabs and more than FCUs, and may well be the specimen of choice for screening.

COX-2 inhibition affects growth rate of Chlamydia muridarum within epithelial cells

Chlamydiae alter apoptosis of host target cells, which regulates their growth. Cyclooxygenase-2 (COX-2), the rate-limiting enzyme for prostaglandin E2 (PGE2) production, modulates epithelial cell survival. We addressed whether endogenous PGE2 alters chlamydial growth or apoptosis of epithelial cells infected with Chlamydia muridarum. PGE2 is secreted by infected host cells in the genital tract (GT). Using immunohistochemical techniques, we found that COX-2 enzyme was localized to epithelial cells in the GT in vivo. Pellets of the COX-2 enzyme inhibitor, NS-398, and placebo were implanted in mice subcutaneously and released a constant amount of these chemicals throughout the infection. NS-398-treated mice were found to exhibit 10-fold lower bacterial load than the placebo group on day 3 post infection, suggesting disruption of the chlamydial developmental cycle. To prove this, the human lung adenocarcinoma cell line A549 was then infected with different MOIs of C. muridarum in the presence of multiple concentrations of NS-398 in vitro. There was no difference in inclusion forming units (IFUs) between NS-389-treated and untreated cells. We also found no alterations in C. muridarum IFUs in A549 cells transfected with a 2.0 kb cDNA fragment of human COX-2 cloned in the sense (S) or anti-sense (AS) orientation. However, the inclusion size was reduced and the number of EB was significantly diminished during reinfection in AS-transfected cells. In addition, the absence of COX-2 did not significantly modify apoptosis in infected cells. In total, COX-2 deficiency reduces the infectious burden in vivo and may modulate transmission of the organism.

Nucleic acid amplification tests for gonorrhea and chlamydia: practice and applications

Nucleic acid amplification tests (NAATs), which are highly sensitive and specific, have provided the ability to use alternative sam-ple types for the diagnosis of sexually transmitted infections (STIs). Self-collected genital specimens, such as urine or even vaginal swabs, can now be accurately used to diagnose gonorrhea or chlamydia infections. In many cases, use of these sample types can decrease the necessity for a clinician to perform a pelvic examination on women or to collect a urethral swab from men, thus extending the diagnostic capability for detecting these infections to nonclinic screening venues. As most chlamydia infections and many gonorrhea infections are asymptomatic, the use of NAATs for self-collected samples greatly increases the types and numbers of patients that can be screened outside of clinic settings. Self-sampling also allows clinicians to easily screen patients in the clinic for STIs who are not presenting for pelvic or urogenital examinations. The application of NAATs to self-collected specimens has the potential to augment public health programs designed to control the epidemic of STIs in the community.

Comparison of strand displacement and ligase chain amplification for detection of Chlamydia trachomatis infection in urogenital specimens

Two amplification tests for the diagnosis of Chlamydia trachomatis infection, namely the ligase chain reaction (LCx) and the strand displacement assay (ProbeTec), were compared using samples from 1183 patients at sexually transmitted disease clinics. The overall prevalence of positive results was 8.0%, with agreement between the two assays of 98.8%. For endocervical, urethral and male urine samples, agreement was 99.3%, 99.4% and 97.7%, respectively. For ten discrepant samples, alternative amplification assays suggested that the LCx and ProbeTec assays gave erroneous results in six and four cases, respectively. Inhibition of amplification was observed with three (0.25%) urine specimens.

Spontaneous Resolution of Asymptomatic Chlamydia trachomatis in Pregnancy

OBJECTIVE

We sought to estimate the rate of spontaneous resolution of asymptomatic Chlamydia trachomatis in pregnancy and to evaluate factors associated with its resolution.

METHODS

A cohort of women enrolled in a large multicenter randomized bacterial vaginosis antibiotic trial (metronidazole versus placebo) that, when randomly allocated, had asymptomatic C trachomatis diagnosed by urine ligase chain reaction (from frozen archival specimens) between 16(0/7) and 23(6/7) weeks were included. The urine ligase chain reaction is a highly accurate predictor of genital tract chlamydial infection. A follow-up ligase chain reaction was performed between 24(0/7) and 29(6/7) weeks.

RESULTS

A total of 1,953 women were enrolled in the original antibiotic trial; 1,547 (79%) had ligase chain reaction performed both at randomization and follow-up. Women receiving antibiotics effective against Chlamydia between randomization and follow-up or having symptomatic Chlamydia infection were excluded (26 women). Of the 140 women (9%) who were diagnosed as positive via the initial ligase chain reaction assay, 61 (44%) had spontaneous resolution of Chlamydia by the follow-up ligase chain reaction assay. Factors associated with spontaneous resolution included older age (P = .02), more than 5 weeks from randomization to follow-up (P = .02), and a greater number of lifetime sexual partners (P = .02). Using a logistic regression model, maternal age and a greater-than-5-week follow-up interval remained significant; for every 5-year increase in maternal age, the odds of a positive result on the ligase chain reaction test at follow-up decreased by 40% (odds ratio 0.6; 95% confidence interval 0.4-0.9). Race, substance abuse, parity, and treatment with metronidazole were not associated with spontaneous resolution. Gram stain score and vaginal pH at randomization and follow-up also were not associated.

CONCLUSION

The prevalence of asymptomatic C trachomatis in pregnancy was 9%; infection resolved spontaneously in almost half of these women. The association of older age and increasing time interval to spontaneous resolution of Chlamydia is consistent with a host immune-response mechanism.

Urine nucleic acid amplification tests for the diagnosis of sexually transmitted infections in clinical practice

PURPOSE OF REVIEW

With the advent of highly sensitive and specific nucleic acid amplification assays, this report will demonstrate that self-collected genital specimens, such as urine or even vaginal swabs can be accurately used to diagnose sexually transmitted infections.

RECENT FINDINGS

Use of self collected samples can eliminate the necessity of a clinician to perform a pelvic examination for women or collect a urethral swab for men, thus extending the diagnostic capability for sexually transmitted infections to non-clinic screening venues. As many sexually transmitted infections are asymptomatic, this ability to use self-sampling greatly increases the numbers of patients that can be screened, and has the potential to augment public health programs designed to control the epidemic of sexually transmitted infections in the community. Patient collected samples are highly acceptable, highly accurate, and are becoming widely used. Self-sampling also allows clinicians to easily screen patients in the clinic, who are not presenting for pelvic or urogenital examinations, for sexually transmitted infections.

SUMMARY

Highly accurate molecular tests and easily obtained self-collected urogenital samples represent the ideal combination for obtaining the public health goal of decreasing the sexually transmitted infection epidemic among sexually active persons in the United States today.

Home STI testing: the adolescent female's opinion

PURPOSE

To assess sexually active adolescent females' attitudes of home tests for sexually transmitted infections.

METHODS

This study represents a follow-up to a study on adolescent attitudes toward different sampling methods for STI testing. In the initial study participants completed a pre-examination health survey, provided first void urine (FVU) and self-collected vaginal swab samples followed by a pelvic examination with STI screening by endocervical swabs. Participants' attitudes about the three collection techniques were assessed at the end of the visit. For the current study, this same group of ethnically diverse adolescents (13-20-years-old) was contacted by telephone 9 months after their initial clinic visit to re-assess their attitudes about the three specimen collection techniques and to evaluate their attitudes regarding the use of home STI testing. Friedman tests of mean ranks evaluated teens' rankings of STI sampling methods and multivariate regression analysis was used to identify predictors of home test preference.

RESULTS

Home urine testing was the first choice for STI screening followed by the FVU, self-obtained vaginal swab and endocervical swab collected in a clinical setting. FVU was preferred to self-collected vaginal swabs (p = .01). Adolescents who worried about having an STI were more likely to favor home urine testing (OR 5.5, p = .01). Only 22% would seek any STI screening if asymptomatic.

CONCLUSIONS

Because young women preferred home STI testing, this may be an additional option, as the foundation for such testing kits has progressed. Adolescent preferences may be heavily influenced by the pelvic examination experience. Because of the largely asymptomatic nature of CT infections, multiple screening options (clinical and home-based) need to be available to increase access to care.

Sex Partner Concurrency, Geographic Context, and Adolescent Sexually Transmitted Infections

BACKGROUND

Geographic areas characterized by a high prevalence of sexually transmitted infections (STIs) are critical to the maintenance and persistence of STIs within populations. Sex partner concurrency has been shown to be associated with increased risk for individual-level STIs.

OBJECTIVES

The objectives of this study were to determine whether gonorrhea rate per census block group and sex partner concurrency independently and interactively are associated with a current bacterial STI among adolescents.

STUDY

Face-to-face interviews and urine testing for Chlamydia trachomatis and Neisseria gonorrhoeae were conducted among female, sexually active, 14- to 19-year-olds presenting for reproductive clinic care between August 2000 and June 2002.

RESULTS

Gonorrhea rate per census block group and sex partner concurrency were not independently but were interactively associated with a current bacterial STI. Among participants with a main sex partner who practiced concurrency, living in high-prevalence geographic areas was significantly associated with a current bacterial STI.

CONCLUSIONS

The results suggest that geographic context may moderate an adolescent sex partner's behaviors. The research adds to the basic understanding of sexually transmitted disease transmission and acquisition in a high-prevalence inner-city setting.

Performance of the MagNA pure LC robot for extraction of Chlamydia trachomatis and Neisseria gonorrhoeae DNA from urine and swab specimens

DNA from uncentrifuged urines (n = 195 and n = 202) and cervical swabs (n = 221 and n = 601) was extracted by the MagNA Pure LC robot and the Amplicor method to validate the robot's extraction for Chlamydia trachomatis and Neisseria gonorrhoeae testing by Roche PCR. The robot provided a highly sensitive and specific method of DNA extraction.

The effect of urine testing in evaluations of the sensitivity of the Gen-Probe Aptima Combo 2 assay on endocervical swabs for Chlamydia trachomatis and neisseria gonorrhoeae: the infected patient standard reduces sensitivity of single site evaluation

BACKGROUND

The Gen-Probe APTIMA Combo 2 (AC2) assay is a second-generation transcription-mediated amplification assay for the detection of Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG).

GOAL

The goal of this study was to evaluate AC2 performance of endocervical (cx) swabs for the detection of CT and NG using either a specimen or an infected patient standard.

STUDY DESIGN

In a multicenter clinical study, we compared AC2 with Abbott's ligase chain reaction (LCR) and Roche's polymerase chain reaction (PCR; Amplicor or COBAS) for CT, and we compared AC2 with Abbott's LCR and culture for NG. A total of 1569 females were enrolled in the study; we collected cx and first-catch urine (FCU) specimens.

RESULTS

CT prevalence was 13.3% for cx specimens and 13.7% for FCU specimens. NG prevalence was 8.7% and 7.9% for cx and FCU specimens, respectively. When based only on cx specimens, AC2, LCR, and PCR sensitivities for CT were 99.4%, 95.6%, and 95.6%, respectively. However, cx sensitivity for CT was reduced to 92.1%, 86.6%, and 87.1% for each respective assay when based on both cx and FCU specimen results (infected patient standard). NG sensitivities for AC2, LCR, and culture based solely on cx specimen results were 99.2%, 96.1%, and 85.9%, respectively. Based on infected patient standard, the sensitivities of each respective assay were 98.5%, 93.9%, and 84.0%.

CONCLUSIONS

The infected patient standard reduces the sensitivity of the endocervical evaluation because some infected patients are positive only with FCU. The reduction in sensitivity is greater when testing for CT. Specificities improved slightly, because some unique cx positives, initially classified as false-positive were confirmed by a positive FCU result. Sensitivity of AC2 was higher than LCR, PCR, and culture. Specificity was slightly lower, but discrepant analysis (using alternate TMA targets) of apparent AC2 false-positives showed that 75% to 80% were true-positives.

Limitations of screening tests for the detection of Chlamydia trachomatis in asymptomatic adolescent and young adult women

OBJECTIVE

The purpose of this study was to examine the performance of different test types, specimen sources, and collection methods for screening of genital Chlamydia trachomatis infection in young women.

STUDY DESIGN

Asymptomatic women aged 16 to 25 years collected their own vaginal swabs and a first-voided urine specimen; a clinician collected urethral, vaginal, and endocervical swabs for culture and nucleic acid amplification tests, polymerase chain reaction and ligase chain reaction. A positive culture, 2 positive nucleic acid amplification tests, or 1 positive nucleic acid amplification test confirmed by a separate nested polymerase chain reaction comprised the criterion standard to define a C. trachomatis-infected woman.

RESULTS

The prevalence of C. trachomatis was 22% (30/139 women). All 9 test results were available for 126 participants (91%). Sensitivities were comparable for polymerase chain reaction and ligase chain reaction (52%-63%), except for urine polymerase chain reaction (44%), and were lower for culture (22%-37%); specificities were 99% to 100%, except for urine ligase chain reaction (91%). Positive predictive values were >93%, except for urine ligase chain reaction (65%); negative predictive values were 83% to 91%. Combining nucleic acid amplification test results from 2 different specimens improved sensitivities without compromising specificity.

CONCLUSION

When C. trachomatis infection was defined by multiple tests from different specimen sources, the sensitivity of any 1 test from a single specimen source was lower than generally reported. The limitations of the use of a single test to identify C. trachomatis infection should be considered when test type, specimen source, and collection method for screening young women is being determined.

Volume effect on sensitivity of nucleic acid amplification tests for detection of Chlamydia trachomatis in urine specimens from females

Nucleic acid amplification tests (NAATs) for the detection of Chlamydia trachomatis are routinely used on first-catch urine (FCU) specimens. We analyzed data from a head-to-head comparison of NAATs on female FCU specimens and found that the volume of urine collected could affect test performance.

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.

Comparing first-void urine specimens, self-collected vaginal swabs, and endocervical specimens to detect Chlamydia trachomatis and Neisseria gonorrhoeae by a nucleic acid amplification test

We set out to determine the prevalences of Chlamydia trachomatis and Neisseria gonorrhoeae by ligase chain reaction as well as to determine the prevalence of Trichomonas vaginalis by culture in a large and diverse national sample of non-health-care-seeking young women entering the military; we also sought to compare the abilities of three different techniques of collecting specimens (first-void urine, self-collected vaginal swab, and clinician-collected endocervical swab) to identify a positive specimen. A cross-sectional sample of young women was voluntarily recruited; as a part of their routine entry pelvic examination visit, they completed a self-administered reproductive health questionnaire and provided first-void urine (used to detect C. trachomatis and N. gonorrhoeae) and self-collected vaginal swabs (used to detect C. trachomatis, N. gonorrhoeae, and T. vaginalis). The number of positive tests divided by the number of sexually active women screened by each sampling method determined the rates of prevalence. The rate of infection with any of the three sexually transmitted diseases (STDs) tested was 14.1%. The total positive rates for each STD (identified by >/=1 specimen) were the following: for C. trachomatis, 11.6%; N. gonorrhoeae, 2.4%; and T. vaginalis, 1.7%. The proportions of positives identified by specimen type were, for C. trachomatis and N. gonorrhoeae, respectively, endocervix, 65 and 40%; urine, 72 and 24%; and vagina, 81 and 72%. The proportions of positives when specimen results were combined were, for C. trachomatis and N. gonorrhoeae, respectively, cervix plus urine, 86 and 49%; cervix plus vagina, 91 and 93%; and vagina plus urine, 94 and 79%. We concluded that STDs were epidemic in this population. Self-collected vaginal swabs identified the highest number of positive test results among single specimens, with the combined cervix-vagina results identifying the highest number of positive results. Self-collected vaginal swab collections are a feasible alternative to cervical specimen collections in this population, and the use of multiple types of specimens increases the positive yield markedly.

Vaginal swabs are appropriate specimens for diagnosis of genital tract infection with Chlamydia trachomatis

Because self-collected vaginal swabs (VS) are potentially very useful for screening asymptomatic women for Chlamydia trachomatis infection, a multicenter study evaluated that specimen with nucleic acid amplification tests (NAATs). The objective was to determine whether VS are equal to Food and Drug Administration (FDA)-cleared specimens (cervical swabs and first-catch urines [FCU]) for diagnosing genital chlamydial infection. All NAATs then commercially available (October 1996 to October 1999) were used (ligase chain reaction [LCx Probe System; Abbott Laboratories, Abbott Park, Ill.]; PCR [Amplicor; Roche Molecular Systems, Branchburg, N.J.]; and transcription-mediated amplification, [Amplified CT Assay; Gen-Probe Inc., San Diego, Calif.]). NAATs were performed on FCU, urethral, cervical, self- and clinician-collected VS. Sensitivity was compared to isolation using cervical and urethral swabs. Agreement of NAAT results between VS and cervical swabs or FCU was calculated. Specimens from 2,517 15- to 25-year-old asymptomatic women attending clinics at nine different centers were evaluated. Results with self- and clinician-collected VS were equivalent and were at least as good as results with FCU and cervical swabs. Across all sites, summary specificities for all specimens were >99%. Among culture-positive women, NAAT sensitivity with VS (93%) was as high as or higher than NAAT sensitivity with cervical swabs (91%) or FCU (80.6%) or culture of cervical swabs (83.5%). VS are appropriate specimens for diagnosing chlamydial genital tract infection by NAATs. That patients can efficiently collect them offers important benefits for screening programs. It would be beneficial for public health programs if the NAAT manufacturers sought FDA clearance for this specimen.

Sustained high prevalence of Chlamydia trachomatis infections in female army recruits

BACKGROUND

Chlamydia trachomatis infections are prevalent among young sexually active females, have serious sequelae, and are mostly asymptomatic. Screening and treatment of infected females has been demonstrated to prevent sequelae such as pelvic inflammatory disease.

GOAL

To assess prevalence and risk factors for chlamydia infection in US Army female recruits, whether these changed over time, and to examine variables contributing to any observed patterns.

STUDY DESIGN

Prevalence study of 23,010 non-healthcare-seeking female Army recruits enrolled in a chlamydia screening program at Fort Jackson, SC, from January 1996 through June 1999. Each of the 4-year cohorts was examined separately for prevalence and risk factors.

MAIN OUTCOME MEASURES

Urine-based testing for C trachomatis by ligase chain reaction was used to determine prevalence, and questionnaires were used to collect demographic and risk information. State home of record for each recruit was transformed into Public Health reporting region: West, Midwest, South, Northeast, and Territories.

RESULTS

Prevalence for all years was 9.51%, but a progressive increase from 8.51% to 9.92% occurred over the course of study (P=0.018). The proportion of individuals reporting specific risk factors during the 90 days preceding the study generally decreased over time. In a regression model, significant risk factors for infection included black race, age 25 years or younger, home-of-record from the South, being screened during years 3 and 4 of the study, more than one sex partner, a new sex partner, and history of any sexually transmitted disease. Condom use was protective. In another model controlling for age and home-of-record from the South, being screened in years 2, 3, and 4 of the study were significantly predictive for being chlamydia positive.

CONCLUSION

A high and slightly increasing prevalence of C trachomatis infection was observed among young females entering the military over 4 consecutive years. Young age, black race, home-of-record from the South, more than one sex partner, a new sex partner, condom use, and a history of having a sexually transmitted disease were correlates of chlamydia infection. Sustained high rates of C trachomatis infection in this population provide clear justification for a chlamydia control program for young women entering the Army consisting of screening at entry on the basis of age and possibly home-of-record together with continued periodic rescreening.

SUMMARY

A study of 23,010 female Army recruits demonstrated that a high prevalence of C trachomatis was sustained during 4 years of observation. Year of study, young age, and being from the South were significant predictors of infection.

LCR testing for gonorrhoea and chlamydia in population surveys and other screenings of low prevalence populations: coping with decreased positive predictive value

OBJECTIVE

Nucleic acid amplification tests have facilitated field based STD studies and increased screening activities. However, even with highly specific tests, the positive predictive value (PPV) of such tests may be lower than desirable in low prevalence populations. We estimated PPVs for a single LCR test in a population survey in which positive specimens were retested.

METHODS

The Baltimore STD and Behavior Survey (BSBS) was a population based behavioural survey of adults which included collecting urine specimens to assess the prevalence of gonorrhoea and chlamydial infection. Gonorrhoea and chlamydial infection were diagnosed by ligase chain reaction (LCR). Nearly all positive results were retested by LCR. Because of cost considerations, negative results were not confirmed. Predicted curves for the PPV were calculated for a single testing assuming an LCR test sensitivity of 95%, and test specificities in the range 95.0%-99.9%, for disease prevalences between 1% and 10%. Positive specimens were retested to derive empirical estimates of the PPV of a positive result on a single LCR test.

RESULTS

579 participants age 18-35 provided urine specimens. 20 (3.5%) subjects initially tested positive for chlamydial infection, and 39 (6.7%) tested positive for gonococcal infection. If positive results on the repeat LCR are taken as confirmation of a "true" infection, the observed PPV for the first LCR testing was 89.5% for chlamydial infection and 83.3% for gonorrhoea. This is within the range of theoretical PPVs calculated from the assumed sensitivities and specificities of the LCR assays.

CONCLUSIONS

Empirical performance of a single LCR testing approximated the theoretically predicted PPV in this field study. This result demonstrates the need to take account of the lower PPVs obtained when such tests are used in field studies or clinical screening of low prevalence populations. Repeat testing of specimens, preferably with a different assay (for example, polymerase chain reaction), and disclosure of the non-trivial potential for false positive test results would seem appropriate in all such studies.

Parallel observation of four methods for screening women under 25 years of age for genital infection with Chlamydia trachomatis

OBJECTIVES

To compare four methods of screening women for Chlamydia trachomatis in an obstetrics and gynaecology department.

STUDY DESIGN

A total of 303 healthy women under 25 years were recruited from antenatal, induced abortion, and family planning clinics. Each underwent parallel testing of endocervical specimens by enzyme immunoassay (EIA) and ligase chain reaction (LCR), vulval swabs by LCR, and urine by LCR. Outcome measures included sensitivity, specificity, acceptability of each method, and the influence of pregnancy.

RESULTS

Overall prevalence (95% CI) was 9.9% (6.8-14%). All methods had a high rate of detection (75-100%), not affected by pregnancy. Urine was most acceptable, followed by vulval swabbing.

CONCLUSIONS

Opportunistic screening of women under 25 years attending obstetric and gynaecology affiliated clinics found high rates of C. trachomatis infection. Both urine and vulval swab methods were highly sensitive, acceptable, and not affected by pregnancy status. Due to pragmatic issues surrounding the urine method, screening by vulval swabs deserves wider recognition.

Pregnant adolescents at risk: sexual behaviors and sexually transmitted disease prevalence

OBJECTIVE

The purpose of this study was to determine the level of high-risk sexual behaviors and the prevalence of chlamydia and gonorrhea among pregnant adolescents.

STUDY DESIGN

These analyses used data from 203 pregnant and 209 nonpregnant adolescents who were recruited from public health clinics. Data sources included interviewer-administered questionnaires, ligase chain reaction tests for chlamydia/gonorrhea in the third trimester of pregnancy, and state health department reports of chlamydia/gonorrhea. Statistical analyses included logistic regression.

RESULTS

Pregnant adolescents were significantly more likely to have not used condoms during sexual intercourse in the past 30 days compared with nonpregnant adolescents, although other sexual risk behaviors were reduced. Nineteen percent of pregnant adolescents had chlamydia or gonorrhea diagnosed during the pregnancy.

CONCLUSION

Pregnant adolescents have high levels of sexually transmitted diseases during pregnancy, and many adolescents use condoms inconsistently. Prenatal care providers may be in a unique position to decrease sexually transmitted diseases among pregnant adolescents by encouraging the reduction of risk behaviors and aggressively screening for sexually transmitted diseases as part of routine prenatal care.

The accuracy and efficacy of screening tests for Chlamydia trachomatis: a systematic review

Screening women for lower genital tract infection with Chlamydia trachomatis is important in the prevention of pelvic inflammatory disease, ectopic pregnancy and infertility. This systematic review aims to state clearly which of the available diagnostic tests for the detection of C. trachomatis would be most effective in terms of clinical effectiveness. The review included all studies published from 1990 onward that evaluated diagnostic tests in asymptomatic, young, sexually active populations. Medline and Embase were searched electronically and key journals were hand-searched. Further studies were identified through the Internet and contact with experts in the field. All studies were reviewed by two reviewers and were scored by Irwig's assessment criteria. Additional quality assessment criteria included a documented sexual history and recording of previous chlamydial infection. The reviews were subjected to meta-analysis and meta-regression. The 30 studies that were included examined three types of DNA-based test--ligase chain reaction (LCR), PCR and gene probe--as well as enzyme immuno-assay (EIA). The results showed that while specificities were high, sensitivities varied widely across the tests and were also dependent on the specimen tested. Pooled sensitivities for LCR, PCR, gene probe and EIA on urine were 96.5%, 85.6%, 92% and 38%, respectively, while on cervical swabs the corresponding sensitivities of PCR, gene probe and EIA were 88.6%, 84% and 65%. Meta-analysis demonstrated that DNA amplification techniques performed best for both urine and swabs in low prevalence populations. We conclude that nucleic acid amplification tests used on non-invasive samples such as urine are more effective at detecting asymptomatic chlamydial infection than conventional tests, but there are few data to relate a positive result with clinical outcome.

Self-collected vaginal swabs for the detection of multiple sexually transmitted infections in adolescent girls

OBJECTIVE

To evaluate the use of self-collected vaginal swabs to test for Neisseria gonorrhoeae, Chlamydia trachomatis, and Trichomonas vaginalis, and to describe the acceptability of this technique to adolescents.

DESIGN

Comparison of a new protocol for sexually transmitted infection (STI) testing with the current standard of care, using the same subjects. Survey of attitudes regarding the self-collection technique.

SETTING

A juvenile correctional facility in western Pennsylvania.

PARTICIPANTS

Convenience sample of 133 detainees, 12-17 years of age.

INTERVENTION

Girls were invited to undergo STI screening using a self-collected vaginal swab. Polymerase chain reaction was used to test this specimen for each of the above three infections. Pelvic exams and endocervical testing were performed at the discretion of the physician performing the intake physical, independent of the study.

MAIN OUTCOME MEASURES

The number of infections diagnosed using the self-testing protocol, compared to the number diagnosed using standard practices; acceptability of the self-collection technique.

RESULTS

Twenty-four percent of sexually active subjects had one or more infections diagnosed by self-testing: 11.3% had C. trachomatis, 8.5% had N. gonorrhoeae, and 11.7% had T. vaginalis. Only 30% of subjects with infections had pelvic exams while detained; therefore 70% of girls with infections would have been missed in the absence of the self-testing option. The self-collection technique was acceptable to 95% of subjects.

CONCLUSIONS

STI testing using self-collected vaginal specimens is highly acceptable to adolescent girls, and can dramatically increase the detection rate for these three treatable infections when pelvic exams are not performed.

Head-to-head multicenter comparison of DNA probe and nucleic acid amplification tests for Chlamydia trachomatis infection in women performed with an improved reference standard

Few evaluations of tests for Chlamydia trachomatis have compared nucleic acid amplification tests (NAATs) with diagnostic tests other than those by culture. In a five-city study of 3,551 women, we compared the results of commercial ligase chain reaction (LCR) and PCR tests performed on cervical swabs and urine with the results of PACE 2 tests performed on cervical swabs, using independent reference standards that included both cervical swabs and urethral swab-urine specimens. Using cervical culture as a standard, the sensitivities of PACE 2, LCR, and PCR tests with cervical specimens were 78.1, 96.9, and 89.9%, respectively, and the specificities were 99.3, 97.5, and 98.2%, respectively. Using either cervical swab or urine LCR-positive tests as the standard decreased sensitivities to 60.8% for PACE 2 and to 75.8 and 74.9% for PCR with cervical swabs and urine, respectively. Specificities increased to 99.7% for PACE 2 and to 99.7 and 99.4% for PCR with cervical swabs and urine, respectively. Sensitivities with a cervical swab-urine PCR standard were 61.9% for PACE 2 and 85.5 and 80.8% for LCR with cervical swabs and urine, respectively. Specificities were 99.6% for PACE 2 and 99.0 and 98.9% for LCR with cervical swabs and urine, respectively. Cervical swab versus urine differences were significant only for PCR specificities (P = 0.034). Overall, LCR sensitivity exceeded that of PCR, and sensitivities obtained with cervical swabs exceeded those obtained with urine specimens by small amounts. These data have substantiated, using a large multicenter sample and a patient standard, that LCR and PCR tests performed on endocervical swabs and urine are superior to PACE 2 tests for screening C. trachomatis infections in women. In our study, NAATs improved the detection of infected women by 17 to 38% compared to PACE 2.

Effectiveness of a mobile medical van in providing screening services for STDs and HIV

This retrospective study assesses the efficacy of a mobile medical van in screening high risk individuals and identifying new cases of HIV and other sexually transmitted diseases (STDs) in an urban setting from July 1996 through March 1997. High risk sex and drug use were common, while consistent condom use was rare. Relatively few patients were screened for STDs; positive cases represented only a small proportion of the STD cases identified in the study community. The mobile program, however, accounted for 11.5% of all HIV tests conducted at public test sites in the city. Mobile medical programs have the potential to improve STD and HIV control efforts by providing services to high risk individuals who may lack access to care elsewhere. Doing so, however, will require more active case finding techniques, including new, less invasive techniques to test asymptomatic individuals.

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.

Evaluation of dry and wet transported intravaginal swabs in detection of Chlamydia trachomatis and Neisseria gonorrhoeae infections in female soldiers by PCR

Screening women for sexually transmitted diseases (STD) in nonclinic settings is highly desirable because many infections are asymptomatic. This is especially true for military women, for whom logistical, social, and other job-related obstacles present barriers to accessing medical care. We assessed the accuracy of intravaginal swabs transported by mail in a wet versus a dry state for PCR (Amplicor CT/NG test) detection of chlamydia and gonorrhea infections in a cross-sectional study of 793 active-duty military women attending an STD clinic. PCR tests of vaginal swabs (wet and dry) were compared to local clinical methods used on cervical swabs. Standard wet vaginal swab PCR testing detected more chlamydia (11.6%) than cervical enzyme immunoassay (9.3%). For detection of chlamydia using wet swabs, the sensitivity and specificity compared with adjudicated true positives were 94.6% (87 of 92) and 99.3% (696 of 701), respectively. Comparing dry swabs to true-positives for chlamydia, the sensitivity was 91.3% (84 of 92) and the specificity was 99.3% (696 of 701). Standard wet vaginal swab PCR detected more gonorrhea (3.3%) than routine cervical culture (2.1%). The sensitivity and specificity of PCR testing of wet swabs compared to true-positives (infected patients) were 96.3% (26 of 27) and 98.2% (752 of 766) for gonorrhea, respectively. For gonorrhea, the sensitivity and specificity of dry swabs compared to true-positives (infected patients) were 88.9% (24 of 27) and 98.3% (753 of 766), respectively. PCR testing of wet and dry transported intravaginal swabs to detect chlamydia and gonorrhea infections was an accurate diagnostic method for military women.

Use of ligase chain reaction for laboratory identification of Chlamydia trachomatis and Neisseria gonorrhoeae in adolescent women

STUDY OBJECTIVE

To compare the ligase chain reaction (LCR) with culture for the detection of Neisseria gonorrhoeae (GC) and with culture and direct fluorescent antibody (DFA) for identification of Chlamydia trachomatis (CT) in cervical specimens from adolescent women.

DESIGN

A prospective study of test performance.

SETTING

Two urban, hospital-based adolescent clinics.

PARTICIPANTS

Adolescent women aged 12-22 yr undergoing pelvic examination for routine sexually transmitted disease (STD) screening or symptoms suggestive of an STD.

MAIN OUTCOME MEASURES

LCR results were considered to be true positives if confirmed by culture and/or DFA (CT only). Discrepant LCR results were confirmed by testing an alternative locus.

RESULTS

With 538 subjects, LCR for CT had a sensitivity of 98.4% (61/62) and specificity of 96.4% (459/476) prior to resolution and a sensitivity of 98.6% (70/71) and specificity of 99.6% (459/461) after resolution. With 1225 subjects, LCR for GC had a sensitivity of 90.0% (54/60) and specificity of 99.4% (1158/1165) prior to resolution and a sensitivity of 90.6% (58/64) and specificity of 100% (1158/1158) after resolution. CT culture alone identified 80% of the true positives and DFA alone only identified 72%. GC culture alone identified 94% of the true positives.

CONCLUSIONS

LCR is an extremely sensitive and specific rapid test, utilizing a single swab and convenient room-temperature storage and transport of specimens. LCR testing of cervical specimens for CT in adolescent women is a better test for detecting CT infection than culture or DFA. LCR testing for cervical GC infection may provide an advantage over culture in circumstances in which optimal transport conditions and viability of the organism cannot be assured.

Incidence and repeat infection rates of Chlamydia trachomatis among male and female patients in an STD clinic: implications for screening and rescreening

BACKGROUND

Nucleic acid amplification tests permit widespread screening for Chlamydia trachomatis. However, the public health benefit of screening may be reduced by high chlamydia incidence and repeat infection rates.

GOAL

To study chlamydia incidence and repeat infection among clients of a sexually transmitted disease (STD) clinic.

STUDY DESIGN

A retrospective cohort study of all clients tested for chlamydia on two or more occasions during a 30-month period.

RESULTS

Between January 1, 1997 and June 30, 1999, 3568 clients were tested on multiple occasions. Of these, 491 (13.8%) had positive test results at their first visit (baseline infections), and 385 (10.8%) had positive results at a subsequent visit (incident infections). The overall incidence was 11.7 per 100 person-years of follow-up evaluation (95% CI, 10.6-12.9). The incidence was significantly higher among those 25 years of age or younger (19.7/100 person-years; 95% CI, 17.3-22.2) than among older subjects (6.8/100 person-years, 95% CI, 5.7-7.9; relative hazard, 3.0; 95% CI, 2.5-3.7). The incidence of new infections among persons without a baseline infection was 10.0 per 100 person-years (95% CI, 8.8-11.2), whereas the incidence of repeat infections was 23.6 per 100 person-years (95% CI, 18.9-28.2; relative hazard, 2.4; 95% CI, 1.9-3.0), with repeat infections accounting for 26% of all incident infections. In the multivariate analysis, the factors associated with new infections included young age, black race, male gender, history of sexually transmitted disease, a new sex partner in the previous 30 days, and inconsistent condom use. The factors associated with repeat infection were younger age, nonuse of condoms, and no treatment after contact with a partner who had a diagnosis of chlamydia or a chlamydia-related condition, as measured at the initial visit.

CONCLUSIONS

Among clients making multiple visits to the clinic, repeat infection rates were significantly higher than new infection rates, likely because of reexposure to untreated partners. These findings point to the need for more effective strategies to prevent chlamydia infection, including enhanced partner management services and rescreening.

Comparison of a polymer conjugate-enhanced enzyme immunoassay to ligase chain reaction for diagnosis of Chlamydia trachomatis in endocervical swabs

Two endocervical swabs from each of 1,123 women were collected into manufacturer-supplied transport tubes and tested for Chlamydia trachomatis by a polymer conjugate-enhanced (PCE) enzyme immunoassay (EIA) (IDEIA PCE Chlamydia; DAKO) and a ligase chain reaction assay (LCx Chlamydia; Abbott). After confirmation by the EIA blocking test, the sensitivity of the IDEIA PCE remained at 91.8% and the specificity increased from 98.2 to 99.8% compared to LCx.

Prevention of sexually transmitted diseases and HIV in young military men: evaluation of a cognitive-behavioral skills-building intervention

BACKGROUND

Military personnel deployed to foreign countries with high endemic rates of sexually transmitted diseases (STDs) are at risk.

GOAL

To evaluate a cognitive-behavioral, skills-building intervention to prevent STDs in junior, enlisted, male US Marines deployed to the Western Pacific aboard ships with periodic liberty visits to foreign ports.

STUDY DESIGN

This study, using a quasi-experimental design, assigned 584 men to a cardiopulmonary resuscitation training (n = 288) or a cognitive-behavioral intervention (n = 296). The intervention aimed to increase prevention knowledge, reduce high-risk psychosocial (motivation) factors, and build decision-making and communication skills to reduce risky sexual behaviors and alcohol consumption.

RESULTS

Participation in the intervention was associated with increased knowledge regarding symptoms and treatment of STDs and HIV (P < 0.001), decreased alcohol use (P < 0.01), and sexual risk (P < 0.01) during liberty ports of call.

CONCLUSION

A multiple-session, cognitive-behavioral, skills-building intervention can be successfully implemented for deployed military personnel.

Screening for chlamydial infection

OBJECTIVES

To examine data on the effectiveness of screening for chlamydial infection by a physician or other health care professional. Specifically, we examine the evidence that early treatment of chlamydial infection improves health outcomes, as well as evidence of the effectiveness of screening strategies in nonpregnant women, pregnant women, and men, and the accuracy of tests used for screening. This review updates the literature since the last recommendation of the U.S. Preventive Services Task Force published in 1996.

SEARCH STRATEGY

We searched the topic of chlamydia in the MEDLINE, HealthSTAR, and Cochrane Library databases from January 1994 to July 2000, supplemented by reference lists of relevant articles and from experts in the field. Articles published prior to 1994 and research abstracts were cited if particularly important to the key questions or to the interpretation of included articles.

SELECTION CRITERIA

A single reader reviewed all English abstracts. Articles were selected for full review if they were about Chlamydia trachomatis genitourinary infections in nonpregnant women, pregnant women, or men and were relevant to key questions in the analytic framework. Investigators read the full-text version of the retrieved articles and applied additional eligibility criteria. For all topics, we excluded articles if they did not provide sufficient information to determine the methods for selecting subjects and for analyzing data.

DATA COLLECTION AND ANALYSIS

We systematically reviewed three types of studies about screening in nonpregnant women that relate to three key questions: (1) studies about the effectiveness of screening programs in reducing prevalence rates of infection, (2) studies about risk factors for chlamydial infection in women, and (3) studies about chlamydial screening tests in women. Our search found too few studies on pregnant women to systematically review, although pertinent studies are described. We systematically reviewed two types of studies about screening in men: (1) studies about prevalence rates and risk factors for chlamydial infection in men and (2) studies about chlamydial screening tests in men.

MAIN RESULTS

Nonpregnant women. The results of a randomized controlled trial conducted in a large health maintenance organization indicate that screening women selected by a set of risk factors reduces the incidence of pelvic inflammatory disease (PID) over a 1-year period. Changes in population prevalence rates have not been well documented because few studies have employed a representative population sample. Age continues to be the best predictor of chlamydial infection in women, with most studies evaluating cut-offs at age younger than 25 years. Other risk factors may be useful predictors, but these are likely to be population specific. To determine the accuracy of screening tests for women, we retrieved and critically reviewed 34 articles on test performance. Results indicate that endocervical swab specimens and first-void urine specimens have similar performance when using DNA amplification tests and have better sensitivity than endocervical culture. Recurrent chlamydial infections in women have been associated with increased risks for PID and ectopic pregnancies. Pregnant women. The Second Task Force recommendations for screening pregnant women were based on two major studies demonstrating improved pregnancy outcomes following treatment of chlamydial infection. We identified no recent studies on this topic in our literature search. Very few studies describe risk factors for chlamydial infection in pregnant women. Nonculture testing techniques appear to perform well in pregnant women, although studies are limited. Men. No studies described the effectiveness of screening or early treatment for men in reducing transmission to women or in preventing acute infections or complications in men. Studies of prevalence rates and risk factors for chlamydial infection in men are limited. Age lower than 25 years is the strongest known risk factor cited so far. Results of urethral swab specimens compared to first-void urine specimens were similar for DNA amplification tests. DNA amplification techniques are more sensitive than culture.

CONCLUSIONS

Screening women for Chlamydia trachomatis reduces the incidence of PID, and it is associated with reductions in prevalence of infection in uncontrolled studies. No studies were found to determine whether screening asymptomatic men would reduce transmission or prevent acute infections or complications. Age is the strongest risk factor for men and women. A variety of tests can detect chlamydial infection with acceptable sensitivity and specificity, including new DNA amplification tests that use either endocervical swabs in women, urethral swabs in men, or first-void urine specimens from men and women.

Determinants of persistent and recurrent Chlamydia trachomatis infection in young women: results of a multicenter cohort study

BACKGROUND

Sequelae of genital Chlamydia trachomatis infection in women are more strongly linked to repeat infections than to initial ones, and persistent or subsequent infections foster continued transmission.

OBJECTIVE

To identify factors associated with persistent and recurrent chlamydial infection in young women that might influence prevention strategies.

METHODS

Teenage and young adult women with uncomplicated C trachomatis infection attending reproductive health, sexually transmitted disease, and adolescent medicine clinics in five US cities were recruited to a cohort study. Persistent or recurrent chlamydial infection was detected by ligase chain reaction (LCR) testing of urine 1 month and 4 months after treatment.

RESULTS

Among 1,194 women treated for chlamydial infection, 792 (66.4%) returned for the first follow-up visit, 50 (6.3 %) of whom had positive LCR results. At that visit, women who resumed sex since treatment were more likely to have chlamydial infection (relative risk [RR], 2.0; 95% CI, 1.03-3.9), as were those who did not complete treatment (RR, 3.4; 95% CI, 1.6-7.3). Among women who tested negative for C trachomatis at the first follow-up visit, 36 (7.1%) of 505 had positive results by LCR at the second follow-up visit. Reinfection at this visit was not clearly associated with having a new sex partner or other sexual behavior risks; new infection was likely due to resumption of sex with untreated partners. Overall, 13.4% of women had persistent infection or became reinfected after a median of 4.3 months, a rate of 33 infections per 1,000 person months.

CONCLUSIONS

Persistent or recurrent infection is very common in young women with chlamydial infection. Improved strategies are needed to assure treatment of women's male sex partners. Rescreening, or retesting of women for chlamydial infection a few months after treatment, also is recommended as a routine chlamydia prevention strategy.

Comparison of the urine-based ligase chain reaction test to culture for detection of Chlamydia trachomatis and Neisseria gonorrhoeae in pediatric sexual abuse victims

BACKGROUND

The urine-based ligase chain reaction (LCR) assay for Chlamydia trachomatis and Neisseria gonorrhoeae is an attractive alternative to culture because of the relative ease with which specimens may be collected, transported and processed. In addition LCR offers superior sensitivity while maintaining high specificity when compared with culture in various studies of adolescents and adults. A study comparing LCR to culture has not been published concerning children.

METHODS

We conducted a prospective, comparison trial of the urine-based LCR test for Chlamydia trachomatis and Neisseria gonorrhoeae as compared with culture among children at a specialized referral center for evaluation for alleged sexual assault. Of the 1,010 children presenting to the center during the study period, 164 met the study requirements for risk of a sexually transmissible disease and collection of both culture and urine LCR specimens.

RESULTS

Eight specimens tested positive by both methods for C. trachomatis. Another 10 specimens tested positive for C. trachomatis by LCR but were negative by culture. No patient with a negative LCR for C. trachomatis had a positive culture. For N. gonorrhoeae 2 specimens tested positive by both methods, and 3 specimens tested positive by LCR but negative by culture. No patient with a negative LCR for N. gonorrhoeae had a positive culture.

CONCLUSIONS

The low prevalence of disease in the study population precluded statistical analysis. LCR may prove to be as specific and more sensitive than culture for the detection of C. trachomatis and N. gonorrhoeae in children. Further studies are needed.

Repeat Chlamydia trachomatis infection in women: analysis through a surveillance case registry in Washington State, 1993-1998

Repeat infections with Chlamydia trachomatis are associated with increased risk for long-term sequelae. The authors analyzed the frequency and predictors of repeat chlamydial infection by using a population-based chlamydia registry in Washington State and evaluated whether women would seek care at the same clinic for repeat infections. Among 32,698 women with an appropriately treated initial chlamydial infection during 1993-1998, 15% developed one or more repeat infections during a mean follow-up time of 3.4 years. Among women less than age 20 years at the time of initial infection, 6% were reinfected by 6 months, 11% by 1 year, and 17% by 2 years. Young age was the strongest predictor for one and two or more repeat infections after controlling for the length of follow-up and other variables. Only 36% of the repeat infections were diagnosed at the same clinical setting as the initial infection, and 50% were diagnosed at the same type of clinic. Adolescent girls had the least consistency in the source of care for chlamydia. This study suggests that efforts to prevent repeat chlamydial infection in young women remain an urgent public health priority and that the burden of repeat infection may be substantially higher than estimates from clinic-based studies.

Home sampling versus conventional swab sampling for screening of Chlamydia trachomatis in women: a cluster-randomized 1-year follow-up study

We compared the efficacy of a screening program for urogenital Chlamydia trachomatis infections based on home sampling with that of a screening program based on conventional swab sampling performed at a physician's office. Female subjects, comprising students at 17 high schools in the county of Aarhus, Denmark, were divided into a study group (tested by home sampling) and a control group (tested in a physician's office). We assessed the number of new infections and the number of subjects who reported being treated for pelvic inflammatory disease (PID) at 1 year of follow-up; 443 (51.1%) of 867 women in the intervention group and 487 (58.5%) of 833 women in the control group were available for follow-up. Thirteen (2.9%) and 32 (6.6%) new infections were identified in the intervention group and the control group, respectively (Wilcoxon exact value, P=.026). Nine (2.1%) women in the intervention group and 20 (4.2%) in the control group reported being treated for PID (P=.045), indicating that a screening strategy involving home sampling is associated with a lower prevalence of C. trachomatis and a lower proportion of reported cases of PID.

Feasibility of patient-collected vulval swabs for the diagnosis of Chlamydia trachomatis in a family planning clinic: a pilot study

This pilot study set out to determine the feasibility of using patient-collected vulval swabs, instead of urine, for the diagnosis of female Chlamydia trachomatis infection. Main outcome measures included prevalence of infection and sensitivity, specificity, and acceptability of both test methods. An assessment was also made of those who declined to be tested. Consecutive women under 25 years of age attending a single urban family planning clinic were invited to participate. Sixty-eight percent (103/152) agreed to undergo testing. Overall prevalence was 11.7%. The sensitivity/specificity for the ligase chain reaction (LCR) assayed patient-collected vulval swabs and urine was 100%/100% and 92%/100%, respectively. The acceptability of self-collection was high with 93% characterising the test as 'not bad', 79% recommending it to a friend, and 79% choosing the test next time. Significantly more women, however, would choose urine for testing on a subsequent occasion (p < 0.001). Less than 1/5 of the patients who declined did not take part because of concerns regarding the vulval swab. Patient-collected vulval swabs assayed by LCR represent a non-invasive, sensitive, and acceptable way to detect genital C. trachomatis infection in women attending a family planning clinic. Compared with urine testing, benefits in terms of transport and processing should encourage more widespread use of this approach.

The Preterm Prediction Study: association of second-trimester genitourinary chlamydia infection with subsequent spontaneous preterm birth

OBJECTIVE

This study was undertaken to determine the association between genitourinary tract infection with Chlamydia trachomatis and spontaneous preterm birth.

STUDY DESIGN

Genitourinary tract infection with C trachomatis was determined with a ligase chain reaction assay of voided urine samples collected at 24 weeks' gestation (22 weeks' to 24 weeks 6 days' gestation) and 28 weeks' gestation (27 weeks' to 28 weeks 6 days' gestation). Case patients (spontaneous preterm birth at <37 weeks' gestation; n = 190) and control subjects (delivery at >/=37 weeks' gestation, matched for race, parity, and center; n = 190) were selected from 2929 women enrolled in the Preterm Prediction Study of the National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network.

RESULTS

Genitourinary C trachomatis infection (11% overall) was significantly more common among the case patients than among the control subjects at 24 weeks' gestation (15.8% vs 6.3%; P =.003) but not at 28 weeks' gestation (12.6% vs 10.9%; P =.61). Women with chlamydia infection were more likely to have bacterial vaginosis (57.1% vs 32.9%; P =.002) and a short cervical length (</=25 mm; 33.0% vs 17.9%; P =.02) but not a body mass index <19.8 kg/m(2) (35.0% vs 23.9%; P =.17) or a positive fetal fibronectin test result (7.1% vs 9.5%; P =.62). After adjustment for risk factors for spontaneous preterm birth, women with C trachomatis infection at 24 weeks' gestation were 2 times as likely as uninfected women to have a spontaneous preterm birth at <37 weeks' gestation (odds ratio, 2.2; 95% confidence interval, 1.03-4.78) and 3 times as likely to have a spontaneous preterm birth at <35 weeks' gestation (odds ratio, 3.2; 95% confidence interval, 1.08-9.57).

CONCLUSION

Genitourinary C trachomatis infection at 24 weeks' gestation was associated with a 2-fold to 3-fold increased risk of subsequent spontaneous preterm birth.

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.

Evaluation of a new amplified enzyme immunoassay (EIA) for the detection of Chlamydia trachomatis in male urine, female endocervical swab, and patient obtained vaginal swab specimens

AIMS

To compare the performance of a new generation dual amplified enzyme immunoassay (EIA) with a molecular method for the diagnosis of Chlamydia trachomatis, using a range of urogenital samples, and to assess the reliability of testing self collected vaginal specimens compared with clinician collected vaginal specimens.

METHODS

Two population groups were tested. For the first population group, first void urine samples were collected from 193 male patients with urethritis, and endocervical swabs were collected from 187 high risk commercial sex workers. All urine and endocervical specimens were tested by a conventional assay (IDEIA chlamydia), a new generation amplified immunoassay (IDEIA PCE chlamydia), and the Amplicor polymerase chain reaction (PCR). Discrepant results obtained among the three sample types were confirmed using a nested PCR test with a different plasmid target region. For the second population group, four swab specimens, including one patient obtained vaginal swab, two clinician obtained endocervical swabs, and one clinician obtained vaginal swab, were collected from 91 high risk sex workers. Self collected and clinician collected vaginal swabs were tested by IDEIA PCE chlamydia. Clinician obtained endocervical swabs were assayed by IDEIA PCE chlamydia and Amplicor PCR.

RESULTS

The performance of the IDEIA PCE chlamydia test was comparable to that of the Amplicor PCR test when male urine and female endocervical swab specimens were analysed. The relative sensitivities of IDEIA, IDEIA PCE, and Amplicor PCR on male first void urine specimens were 79.3%, 91.4%, and 100%, respectively. The relative sensitivities of the three tests on female endocervical specimens were 85.0%, 95.0%, and 100%, respectively. The positivity rates for patient collected vaginal specimens and clinician collected vaginal specimens by IDEIA PCE were 25.2% and 23.1%, respectively, whereas those for clinician collected endocervical swabs by PCR and IDEIA PCE were both 27.5%.

CONCLUSIONS

IDEIA PCE chlamydia is a lower cost but sensitive alternative test to PCR for testing male urine samples and female endocervical swabs. In addition, self collected or clinician collected vaginal specimens tested by IDEIA PCE chlamydia are a reliable alternative to analysing endocervical specimens.

Discrepant analysis: a biased and an unscientific method for estimating test sensitivity and specificity

Discrepant analysis is a widely used technique for estimating test performance indices (sensitivity, specificity, etc.) of DNA-amplification tests for detecting infectious diseases. It has recently been claimed that the discrepant analysis-based estimates of specificity are typically less biased than those based on culture and that the discrepant analysis-based specificity shows little appreciable bias. In this article, I show that those conclusions are incorrect. Using a typical example from the published literature, I show that the discrepant analysis-based estimates of sensitivity and specificity can generate a significant and clinically important overestimation of the true sensitivity and specificity values. Moreover, I demonstrate that the concept of discrepant analysis is profoundly flawed and unscientific. It violates a fundamental principle of diagnostic testing-the principle that the new test should not be used to determine the true disease status. Thus, the major problem with discrepant analysis is not only that it is biased but that it is unscientific. Therefore, discrepant analysis should not be adopted for the evaluation of any diagnostic or screening test.