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

Update on the Diagnosis of Sexually Transmitted Infections

Sexually transmitted infections (STIs) are one of the most frequent and universal Public Health problems. Health professionals should be aware of the possibility of STIs due to their high morbidity and the presence of sequelae. The delay in the diagnosis is one of the factors that justifies the difficulty to infections control. Diagnostic tests allow the introduction of aetiological treatment and also lead to treating symptomatic and asymptomatic patients more effectively, as well as to interrupt the epidemiological transmission chain without delay. In this review we have made an update of the main existing diagnostic methods for the more important STIs.

Prevalence and distribution of Chlamydia trachomatis genovars in Indian infertile patients: a pilot study

To determine the prevalence and distribution of Chlamydia trachomatis genovars in patients with infertility by PCR-RFLP and ompA gene sequencing. Prevalence of other etiological agents (viz., Ureaplasma spp. and Mycoplasma hominis) were also assessed. Endocervical swabs were collected from 477 women and urine was collected from 151 men attending the Infertility Clinic. The samples were screened for C. trachomatis by cryptic plasmid, ompA gene and nested ompA gene PCR. Genotyping was performed by PCR-RFLP and sequencing. Samples were screened for Ureaplasma spp. and M. hominis. The prevalence of C. trachomatis in infertile women and their male partners were 15.7% (75 of 477) and 10.0% (15 of 151) respectively. Secondary infertility was significantly associated with chlamydial infection. Genovar E was the most prevalent followed by genovar D and F. Twenty-four C. trachomatis strains were selected for ompA gene sequencing. No mixed infection was picked. Variability in ompA sequences was seen in 50.0%. Both PCR-RFLP and ompA gene sequencing showed concordant results. High prevalence of C. trachomatis in infertile couples warrants routine screening for C. trachomatis infection in all infertile couples. Genotyping of the ompA gene of C. trachomatis may be a valuable tool in understanding the natural history of C. trachomatis infection.

Lawrence JS. Urine Tests for Gonorrhea and Chlamydia: Great Technology but Will the Community Accept It?

Semi-structured interviews were conducted with 311 respondents in seven inner-city communities within the United States in an effort to examine factors that promote regular urine-based screening for chlamydia and gonorrhea. Results suggested that the majority of respondents were in favor of the use of urine-based testing for the detection of sexually transmitted infections (STIs), indicating that regular urine testing is important for diagnosis, early detection, prevention, and treatment of STIs. The most common concerns reported were stigma associated with STIs, the time required for testing, the possibility of receiving inaccurate laboratory results, and the higher cost of urine testing. The ease and accuracy of urine testing in addition to its high acceptance suggest that screening programs for STIs using urine-based testing could be implemented and used quite effectively to control the transmission of STIs.

Background review for the '2015 European guideline on the management of Chlamydia trachomatis infections'

SummaryChlamydia trachomatis infections are major public health concerns globally. Of particular grave concern is that the majority of persons with anogenital Chlamydia trachomatis infections are asymptomatic and accordingly not aware of their infection, and this silent infection can subsequently result in severe reproductive tract complications and sequelae. The current review paper provides all background, evidence base and discussions for the 2015 European guideline on the management of Chlamydia trachomatis infections (Lanjouw E, et al. Int J STD AIDS 2015). Comprehensive information and recommendations are included regarding the diagnosis, treatment and prevention of anogenital, pharyngeal and conjunctival Chlamydia trachomatis infections in European countries. However, Chlamydia trachomatis also causes the eye infection trachoma, which is not a sexually transmitted infection. The 2015 European Chlamydia trachomatis guideline provides up-to-date guidance regarding broader indications for testing and treatment of Chlamydia trachomatis infections; clearer recommendation of using validated nucleic acid amplification tests only for diagnosis; advice on (repeated) Chlamydia trachomatis testing; recommendation of increased testing to reduce the incidence of pelvic inflammatory disease and prevent exposure to infection and recommendations to identify, verify and report Chlamydia trachomatis variants. Improvement of access to testing, test performance, diagnostics, antimicrobial treatment and follow-up of Chlamydia trachomatis patients are crucial to control its spread.

Self-Collected versus Clinician-Collected Sampling for Chlamydia and Gonorrhea Screening: A Systemic Review and Meta-Analysis

BACKGROUND

The increases in STI rates since the late 1990s in Canada have occurred despite widespread primary care and targeted public health programs and in the setting of universal health care. More innovative interventions are required that would eliminate barriers to STI testing such as internet-based or mail-in home and community service testing for patients that are hard to reach, who refuse to go for clinician-based testing, or who decline an examination. Jurisdictions such as New Zealand and some American states currently use self-collected sampling, but without the required evidence to determine whether self-collected specimens are as accurate as clinician-collected specimens in terms of chlamydia and gonorrhea diagnostic accuracy. The objective of the review is to compare self-collected vaginal, urine, pharyngeal and rectal samples to our reference standard - clinician-collected cervical, urethral, pharyngeal and rectal sampling techniques to identify a positive specimen using nucleic acid amplification test assays.

METHODS

The hierarchical summary receiver operating characteristic and the fixed effect models were used to assess the accuracy of comparable specimens that were collected by patients compared to clinicians. Sensitivity and specificity estimates with 95% confidence intervals (CI) were reported as our main outcome measures.

FINDINGS

We included 21 studies based on over 6100 paired samples. Fourteen included studies examined chlamydia only, 6 compared both gonorrhea and chlamydia separately in the same study, and one examined gonorrhea. The six chlamydia studies comparing self-collection by vaginal swab to a clinician-collected cervical swab had the highest sensitivity (92%, 95% CI 87-95) and specificity (98%, 95% CI 97-99), compared to other specimen-types (urine/urethra or urine/cervix). Six studies compared urine self-samples to urethra clinician-collected samples in males and produced a sensitivity of 88% (95% CI 83-93) and a specificity of 99% (95% CI 0.94-0.99). Taking into account that urine samples may be less sensitive than cervical samples, eight chlamydia studies that compared urine self-collected verses clinician-collected cervical samples had a sensitivity of 87% (95% CI 81-91) and high specificity of 99% (95% CI 0.98-1.00). For gonorrhea testing, self-collected urine samples compared to clinician-collected urethra samples in males produced a sensitivity of 92% (95% CI 83-97) and specificity of 99% (95% CI 0.98-1.00).

CONCLUSION

The sensitivity and specificity of vaginal self-collected swabs compared to swabs collected by clinicians supports the use of vaginal swab as the recommended specimen of choice in home-based screening for chlamydia and gonorrhea. Urine samples for gonorrhea collected by men had comparably high sensitivity and specificity, so could be recommended as they can be left at room temperature for several days, allowing for the possibility of mail-in home-based testing. In populations that may not go for testing at all, do not have the option of clinical testing, or who refuse a clinical examination, self-collected screening would be a good alternative. We recommend that guidelines on how to self-collect gonorrhea and chlamydia urine, vaginal, rectal and pharyngeal specimens be published.

Classical and Molecular Methods for Evaluation of Chlamydia trachomatis Infection in Women with Tubal Factor Infertility

BACKGROUND

Chlamydia trachomatis is the most reported bacterial sexually transmitted disease, especially among young women worldwide. The aim of this study was comparison the prevalence of Chlamydia trachomatis infection in woman with tubal infertility by means of PCR and cell culture techniques.

METHODS

Fifty-one women with confirmed TFI were enrolled in this study in (avicenna infertility Clinic) between January 2010 and January 2011. Cervical swab and cytobrush specimens were collected from each patient by gynecologists and sent to laboratory in transport media. Detection of Chlamydia trachomatis in samples was performed using PCR and bacteria culture in MacCoy cell line. The data were analyzed by Fisher's exact test and independent t-test. Statistical significance was established at a p-value <0.05.

RESULTS

A significant relation was observed between increased the age of first intercourse and chlamydial infection. Six (11.7%) samples had positive PCR result, whereas cell culture results were positive in only 2 (3.9%) samples. A significant relation was also identified between the duration of infertility and infection (p < 0.05) by PCR versus cell culture method.

CONCLUSION

The results showed that PCR is a rapid method, compared to cell culture for detecting Chlamydial organism. It also became clear that the age at first intercourse is important to predict the likelihood of Chlamydia trachomatis.

How reliable are tests for trachoma?--a latent class approach

PURPOSE

Tests for ocular Chlamydia trachomatis have not been well characterized, because there is no gold standard test. Latent class analysis (LCA) was performed to estimate the sensitivity and specificity of laboratory and clinical tests for trachoma in the absence of a gold standard.

METHODS

Individual data from pretreatment, hyperendemic areas in Ethiopia were used. A clustered LCA was performed for three diagnostic tests: PCR and WHO simplified criteria grades of follicular trachoma (TF) and intense trachomatous inflammation (TI).

RESULTS

Data from 2111 subjects in 40 villages were available. TF was estimated to be 87.3% (95% CI, 83.3-90.1) sensitive and 36.6% (95% CI, 23.6-40.3) specific; TI was estimated to be 53.6% (95% CI, 46.1-88.0) sensitive and 88.3% (95% CI, 83.3-92.0) specific, and PCR was estimated to be 87.5% (95% CI, 79.9-97.2) sensitive and 100% (95% CI 69.3-100) specific.

CONCLUSIONS

LCA allows for an estimate of test characteristics without prior assumption of their performance. TF and TI were found to act in a complementary manner: TF is a sensitive test and TI is a specific test. PCR is highly specific but lacks sensitivity. The performance of these tests may be due to the time course of ocular chlamydial infection, and for this reason, results may differ in areas of low prevalence or recent mass treatment (ClinicalTrials.gov number, NCT00221364).

Chlamydia trachomatis genotypes and the Swedish new variant among urogenital Chlamydia trachomatis strains in Finland

Our aims were to genotype Chlamydia trachomatis strains present in urogenital samples and to investigate the occurrence of the Swedish new variant of C. trachomatis in Finland. We genotyped 160 C. trachomatis positive samples with ompA real-time PCR and analyzed 495 samples for the new variant. The three most prevalent genotypes were E (40%), F (28%), and G (13%). Only two specimens containing bacteria with the variant plasmid were detected. It seems that in Finland the percentage of infections due to genotypes F and G has slightly increased during the last 20 years. Genotypes E and G appear to be more common, and genotypes J/Ja and I/Ia appear to be less common in Europe than in the USA. Although the genotype E was the most common genotype among C. trachomatis strains, the new variant was rarely found in Finland.

Epidemiology of Chlamydia trachomatis infection in women and the cost-effectiveness of screening

BACKGROUND

The majority of Chlamydia trachomatis infections in women are asymptomatic, but may give rise to pelvic inflammatory disease (PID) and tubal infertility. Screening programmes aim at reducing morbidity in individuals by early detection and treatment, and at decreasing the overall prevalence of infection in the population. A number of modelling studies have tried to calculate the threshold prevalence of chlamydia lower genital tract infection above which screening becomes cost-effective. There is considerable debate over the exact complication rates after chlamydia infections, and more precise estimates of PID and tubal infertility are needed, for instance to be inserted in economic models.

METHODS

With reference to key studies and systematic reviews, an overview is provided focusing on the epidemiology of chlamydia infection and the risk-estimates of its late complications.

RESULTS

In the literature, the generally assumed risk of developing PID after lower genital tract chlamydia infection varies considerably, and is up to 30%. For developing tubal infertility after PID the risks are 10-20%. This implies that the risk of test-positive women of developing tubal infertility would range between 0.1 and 6%. We included chlamydia IgG antibody testing in a model and estimated a risk of tubal infertility up to 4.6%.

CONCLUSION

The risk of developing late complications after chlamydia lower genital tract infection appears low. High quality RCTs dealing with the transition from cervicitis to infertility are needed to broaden the evidence. In screening programmes, chlamydia antibody testing, as an intermediate marker for potential adverse sequelae, might enable more precise estimates.

Potential triggering infections of reactive arthritis

OBJECTIVES

The aim of the study was to investigate possible triggering infections causing reactive arthritis (ReA) of urogenital origin.

METHODS

One hundred and twenty ReA patients, 85 control group patients with other arthritides (61 with rheumatoid arthritis, 13 with osteoarthritis, and 11 with microcrystal arthritis), and 52 healthy persons were tested for urogenital tract inflammation and several infectious agents. Ligase chain reaction was used for detection of Chlamydia trachomatis (CT). Genital mycoplasmas Ureaplasma urealyticum (Uu) and Mycoplasma hominis (Mh) were tested using the Mycoplasma Duo Test (MDT). Only titres greater than 10(4) CCU/mL were accepted as pathogenecity threshold levels for Uu.

RESULTS

Inflammation of the urogenital tract (most frequently urethritis in men and cervicitis in women) was found in 95% of patients with acute ReA. Possible causative pathogens were identified in 58% of ReA patients. CT was found in 29%, Uu in 21%, and Mh in 8% of patients with ReA. While CT and Uu were found more often in HLA-B27-positive than in HLA-B27-negative patients, this was statistically proved only for CT. In ReA males Uu was found four times more frequently than in men with other arthritides.

CONCLUSIONS

In active ReA of urogenital origin, inflammation of the urogenital tract is found in the majority of patients. Although CT is the main microorganism associated with urethritis in men and cervicitis in women, mycoplasmas, especially Uu, may be possible aetiological factors for ReA.

Urine‐based testing forChlamydia trachomatisusing polymerase chain reaction, leucocyte esterase and urethral and cervical smears

The performance of Roche polymerase chain reaction (PCR) Amplicor to detect Chlamydia trachomatis in first-voided urine specimens from 422 males and 456 females attending two clinics for sexually transmitted infections was evaluated in comparison with cultures of urethral and cervical specimens. At the same time, the ability of leucocyte esterase (LE) in first-voided urine and the presence of leucocytes in urethral and cervical smears to identify C. trachomatis-infected individuals based on PCR and culture was determined. The prevalence of C. trachomatis infection was 10.9% in men and 7.7% in women. Sensitivity, specificity, positive predictive value and negative predictive value of Amplicor was 93.5%, 99.7%, 97.7% and 99.2% in males and 91.4%, 99.5%, 94.1% and 99.3% in females. All Chlamydia-infected men were identified by means of a combination of urethritis (4 leucocytes in the urethral smear) and/or a positive LE test in urine, although the specificity was only 42.2%. In women, the combination of urethritis and/or cervicitis and/or a positive LE test identified 85.7% of Chlamydia-infected patients with a specificity of 38.2%. It is concluded that a combination of urethral and/or cervical smears and LE testing of urine can be used as a screening test to select patients, especially males, for specific C. trachomatis testing.

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.

No evidence for a sustained increase in sexually transmitted diseases among heterosexuals in Amsterdam, the Netherlands: a 12-year trend analysis at the sexually transmitted disease outpatient clinic, Amsterdam

OBJECTIVES

Sexually transmitted diseases (STDs) are on the rise, mainly among men having sex with men (MSM).

GOAL

The goal of this study was to evaluate whether STD increases as seen in MSM are also visible among heterosexuals.

STUDY DESIGN

Attendees of the STD clinic in Amsterdam, The Netherlands, are routinely tested for chlamydia, gonorrhea, and syphilis. Additionally, all women are tested for trichomoniasis. STD time trends of heterosexual attendees between 1994 and 2005 were analyzed by logistic regression and generalized linear models with a negative binomial distribution.

RESULTS

The number of consultations doubled since 1994. However, no long-term increase was seen in the number of syphilis and gonorrhea infections. Additionally, the trichomonas prevalence declined. However, the number of chlamydia infections increased over time.

CONCLUSIONS

Although the number of attendees increased, no evidence for increasing STD incidence was found among heterosexuals. The increase in chlamydia infections can probably be explained by increased screening resulting from increased numbers of attendees.

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.

What is the impact of change in diagnostic test method on surveillance data trends in Chlamydia trachomatis infection?

OBJECTIVE

To describe the impact of change from culture to more sensitive nucleic acid amplification testing (NAAT) tests on the detection of Chlamydia trachomatis in a genitourinary medicine (GUM) clinic population.

METHODS

Data were collected between January 1992 and December 2003 on results of C trachomatis tests on male and female attenders at the Lothian GUM clinic (n = 81 590). Routine diagnosis switched from culture to NAAT methods in September 1998. Association of test result with age, sex, year of test, and test type was analysed using logistic regression.

RESULTS

6.1% (95% CI: 5.7% to 6.5%) of women and 7.1% of men (95% CI: 6.7% to 7.5%) tested positive with culture and 9.9% of women (95% CI: 9.4% to 10.3%) and 11.1% of men (95% CI: 10.7% to 11.5%) tested positive with NAATs. This corresponds to a 56% increase for men (95% CI: 47% to 66%) and 62% for women (95% CI: 50% to 67%). Logistic regression showed that a positive test result was strongly associated with test type with or without adjustment for year of test, sex, and young age.

CONCLUSIONS

The significant increase in chlamydial infections detected following a change from culture to NAATs has important implications for interpretation of trends ascertained from surveillance data. Not all of this can be a direct effect of enhanced sensitivity and there may be indirect effects that improve ascertainment of existing infections. As more laboratories switch to NAATs similar patterns of stepwise increases in positive results are expected and trend analysis based on such surveillance data might thus show an artefactual rise in chlamydia infection rates. Accumulated surveillance data should therefore include timing of introduction of NAAT, so as to take account of under-ascertainment by previous methods.

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.

Nonspecific urethritis and reactive arthritis

Nongonococcal urethritis (NGU) is a common sexually transmitted infection most often caused by Chlamydiae and Mycoplasmae. A few other organisms, as well as some nonsexual factors, also contribute to its etiology. NGU can result in considerable physical and psychological morbidity. In a few cases, it can lead to complications like reactive arthritis, and pelvic inflammatory disease, with their attendant morbidities. Correct diagnosis and treatment is therefore imperative in proper management of these cases. While earlier diagnostic support for these infections was limited and expensive, the advent of new methods like the nucleic acid amplification assays (NAA tests) has contributed significantly to better diagnosis. Treatment as per suggested guidelines and follow up of cases and contacts are all crucial in management. Counseling, including advice on behavior change, goes a long way in preventive strategies.

Herpes simplex virus type 2 prevalence of epidemic proportions in rural Zimbabwean women: association with other sexually transmitted infections

INTRODUCTION

Syndromic management of sexually transmitted infections (STIs) is one important strategy in human immunodeficiency virus (HIV) prevention in developing countries, but there is a scarcity of rural community-based data on the relative prevalences of the STIs. We sought to determine the prevalences of the STIs and their clinical correlates in rural Zimbabwean women.

METHODS

A cross-sectional study was conducted among 527 sexually active, non-pregnant, non-menopausal women between the ages of 20 and 49 years.

RESULTS

The seroprevalence for herpes simplex virus type 2 (HSV-2), HIV, trichomoniasis and syphilis were 64.5, 29.3, 24.7 and 6.2% respectively. HSV-2 seropositivity was significantly associated with current non-syphilitic ulcers (adjusted odds ratio [OR] 4.91, 95% confidence interval [CI] 1.08-22.34, p = 0.040). HSV-2 seroprevalence peaked at the age of 35 whereas HIV peaked at 25. The two diseases were strongly associated (OR 2.92, 95% CI 1.85-4.65, p < 0.001).

CONCLUSION

There is evidence of rural epidemics of both HSV-2 and HIV, and a change in the aetiology of genital ulcers in rural Zimbabwe.

[Up to date in sexually transmitted infections: epidemiology, diagnostic approaches and treatments]

In the last years, there have been important advances in sexually transmitted infections such as genome sequencing of Treponema pallidum, Chlamydia trachomatis or Mycoplasma genitalium; the new taxonomic position of Calymmatobacterium granulomatis; commercial diagnostic systems based on nucleic acid amplification; the emergence of quinolone resistance in Neisseria gonorrhoeae; new therapeutic approaches in vulvovaginal candidiasis that include boric acid; the demonstration that valacyclovir reduces the risk of transmission of genital herpes or the availability of immune-response modifier in the treatment of genital warts, and that are questions in the goal of this review. Viral hepatitis and HIV were no reviewed by space reasons.

Cost-Effectiveness Analysis of Screening Adolescent Males for Chlamydia On Admission to Detention

BACKGROUND

Chlamydia trachomatis infections can lead to serious and costly sequelae. Because chlamydia is most often asymptomatic, many infected youth do not seek testing. Entry to a detention system provides an opportunity to screen and treat many at-risk youth. GOAL The goal of this study was to determine the cost-effectiveness of screening male youth for chlamydia on entry to detention.

STUDY DESIGN

Incremental cost-effectiveness of 3 chlamydia screening strategies was compared for a hypothetical cohort of 4000 male youth per year: 1) universal chlamydia screening using a urine-based nucleic acid amplification test (NAAT), 2) selective NAAT screening of urine leukocyte esterase (LE)-positive urines, and 3) no screening. The model incorporated programmatic costs of screening and treatment and medical cost savings from sequelae prevented in infected males and female partners. The analysis was conducted from the healthcare system perspective.

RESULTS

Chlamydia prevalence in the sampled population of 594 was 4.8%, and the average number of female sexual partners/infected male was 1.6. Universal NAAT screening was the most cost-effective strategy, preventing 37 more cases of pelvic inflammatory disease (PID) and 3 more cases of epididymitis than selective screening and saving an additional 24,000 dollars. The analysis was sensitive to NAAT cost, LE sensitivity, rate of PID development, PID sequelae cost, and number of female partners. Universal screening remained the most cost saving for prevalence as low as 2.8% or higher.

CONCLUSIONS

Universal chlamydia screening of adolescent males on entry to detention was the most cost-effective strategy. Savings are primarily the result of the prevention of PID in recent and future partners of index males. Screening detained male youth using a urine-based NAAT provides a public health opportunity to significantly reduce chlamydia infections in youth at risk for sexually transmitted diseases.

Validation of roche COBAS Amplicor assay for detection of Chlamydia trachomatis in rectal and pharyngeal specimens by an omp1 PCR assay

Screening guidelines for men who have sex with men (MSM) recommend testing of extragenital sites (pharyngeal and rectal) for gonorrhoea and chlamydia. Testing of specimens from these sites is not validated by most commercial nucleic amplification tests, such as the COBAS Amplicor assay. To investigate the utility of the COBAS Amplicor assay for detection of Chlamydia trachomatis in extragenital specimens, this study developed and evaluated confirmatory tests using the omp1 gene as an alternative target for amplification by PCR. Of anal and throat swabs collected from men in male-only saunas, 52 swabs that tested C. trachomatis positive by COBAS Amplicor and 30 swabs that tested as negative were included for confirmatory omp1 PCR testing. A total of 49 (94%) COBAS Amplicor-positive samples were confirmed by the omp1 PCR. A substantial proportion of specimens were confirmed by using a nested omp1 PCR (27%). Not confirmed by any omp1 PCR were three anal swabs (6%). It is most probable that these samples contained lower bacterial levels that were near or below the detection level of the omp1 PCR assays. The findings of this study support the confident reporting of C. trachomatis detected by COBAS Amplicor in extragenital specimens and support the utility of this assay as a screening test for MSM.

Nationwide Increase of Chlamydia trachomatis Infection in Finland

BACKGROUND

Since 1995, the incidence of Chlamydia trachomatis infection has been increasing in Finland, although there have been no major changes in public sexually transmitted disease (STD) services or screening practice.

OBJECTIVES

The objective was to study whether the change in C. trachomatis incidence is significant and to identify specific risk groups.

METHODS

The incidence rates for all C. trachomatis cases notified by laboratories to the National Infectious Disease Register (NIDR) in Finland in 1995-2000 were calculated by gender, age, and domicile. Data from a sentinel STD surveillance network was used to analyze changes of risk-taking behavior in age groups with the highest C. trachomatis rates.

RESULTS

During the 6-year study period, laboratory surveillance data documented an increase in the incidence rate from 23.4 per 10,000 to 29.2 per 10,000. The increase was most evident among people living in nonurban densely populated areas. Highest increase, 1.37-fold (95% confidence interval [CI], 1.29-1.46) in women and 1.69-fold (CI, 1.47-1.92) in men, occurred in the youngest age group (10-19 years old). In 2000, more women, but not men, in the age group of 10-29 years reported 5 or more annual sex partners (18.8%; CI, 16.3-21.6) than in 1995 (8.3%; CI, 5.7-11.5).

CONCLUSION

National surveillance of C. trachomatis infection based on laboratory notification documented increasing incidence rates, especially among adolescents and young people. This risk group should be a target for screening and educational programs to control the epidemic of C. trachomatis infections.

Large-scale testing of women in Copenhagen has not reduced the prevalence of Chlamydia trachomatis infections

OBJECTIVE

To examine the impact of a stable, large-scale enzyme immunoassay (EIA) Chlamydia trachomatis testing situation in Copenhagen, and to estimate the impact of introducing a genomic-based assay with higher sensitivity and specificity.

METHODS

Over a five-year study period, 25 305-28 505 women screened for chlamydial infection each year, corresponding to 19.3% of the female population in Copenhagen, Denmark, were analyzed.

RESULTS

The C. trachomatis age-specific examination percentage and age-specific positive percentage were unchanged during the study period. For EIA, the age-specific positive predictive value of a test decreased from 94% at age 17 to only 50% at age 34 years. Irrespective of the choice of diagnostic test, only about 30% of chlamydial infections would be diagnosed, given current strategies.

CONCLUSION

Although genomic detection assays will increase the positive and negative predictive values of the Chlamydia test result, new screening strategies for both men and women in younger age groups will be necessary if chlamydial infections are to be curtailed.

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.

Confirmation by 16S rRNA PCR of the COBAS AMPLICOR CT/NG test for diagnosis of Neisseria gonorrhoeae infection in a low-prevalence population

The COBAS AMPLICOR CT/NG test is widely used for the diagnosis of Neisseria gonorrhoeae infection using genital swabs or urine samples. Although highly specific, cross-reactivity occurs with some nonpathogenic strains of Neisseria and Lactobacillus species. In low-prevalence populations, even highly specific assays may require confirmatory testing of positive results. We assessed the positive predictive value (PPV) of this test in a low-prevalence (0.5%) setting. Genital and urine specimens testing positive using the COBAS AMPLICOR NG test were retested using an investigational 16S rRNA PCR assay. Additionally, 737 specimens were tested in parallel by both culture and the above PCR protocol. Of 9,772 specimens tested in-house, 168 were positive by the AMPLICOR test; in addition, 62 AMPLICOR-positive specimens were referred to our laboratory for confirmatory testing, yielding 230 positive specimens. Of these, 72 were confirmed positive by 16S rRNA PCR, yielding a specificity of 98.7% and a PPV of 31.3%. Specificity was similar for all specimen types, whereas PPV varied with prevalence: specimens from males, females, urine specimens, and genital swabs had PPVs of 70.8, 13.3, 51.9, and 20.1%, respectively. The PPV was higher when the initial AMPLICOR optical density (OD) was > or =3.5 versus initial and repeat OD readings in an equivocal zone of > or =0.2 to <3.5 (65.1 versus 10.1%; P < 0.001). On repeat testing of specimens with ODs in the equivocal zone, 54 gave ODs of > or =0.2 and <2.0, 35 gave ODs of > or =2.0 and <3.5, and 12 gave ODs of > or =3.5, with 3.7, 20, and 33.3% confirmed positive, respectively (P = 0.004). Comparing PCR to culture as the "gold standard," specificity increased from 96.8 to 99.9% when 16S rRNA PCR was performed on specimens positive by the COBAS AMPLICOR NG test. Confirmatory testing with a more specific method such as 16S rRNA PCR should be considered in low-prevalence populations, especially for specimens with an OD in the equivocal zone.

Chlamydia trachomatis diagnostics

Nucleic acid amplification (NAA) assays for the diagnosis of Chlamydia trachomatis infections started to appear in the peer reviewed literature about 12 years ago and during that period we have seen an incredible effort put into the development and evaluation of commercially developed NAA kits to diagnose and treat infections.

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.

Chlamydia trachomatis in subfertile women undergoing uterine instrumentation. Screen or treat?

Women who undergo uterine instrumentation are considered at risk for pelvic infections by Chlamydia trachomatis, which may derive either from ascending endocervical infections or from reactivation of micro-organisms persisting in the genital tract after previous chlamydia infections. Women presenting at fertility clinics frequently undergo uterine instrumentation (e.g. hysterosalpingography and laparoscopy with hydrotubation). Studies in subfertile women using DNA amplification techniques have shown that the prevalence of endocervical chlamydia infections is low (1.8%). In contrast, in 30-60% of subfertile women chlamydia IgG antibodies can be found in serum, indicating previous chlamydia infections. It has been demonstrated that, several years after chlamydia infections, viable micro-organisms may still be present in the upper genital tract. Therefore, subfertile women with chlamydia antibodies should be considered at risk for reactivation of persistent chlamydia infections after uterine instrumentation, even after exclusion of endocervical chlamydia infections. Moreover, in subfertile women without chlamydia antibodies, the presence of viable micro-organisms in the genital tract cannot be excluded. As a consequence, prophylactic antibiotics before uterine instrumentation should be considered in all subfertile women, instead of endocervical screening for C. trachomatis and treatment of positive cases only.

Cost-effectiveness of five strategies for gonorrhea and chlamydia control among female and male emergency department patients

BACKGROUND

Previous studies have shown screening for gonorrhea and chlamydia to be cost-effective for limiting the sequelae of infection and the associated costs of management.

GOAL

To evaluate the cost-effectiveness of enhanced screening for gonorrhea and chlamydia in an emergency department (ED) setting.

STUDY DESIGN

Five strategies were compared with use of decision analysis for theoretical cohorts of 10,000 female and 10,000 male ED patients aged 18 years to 31 years: standard ED practice, three enhanced screening strategies, and mass treatment. Main outcome measures were untreated gonorrhea or chlamydia cases and their sequelae, transmission to a partner, congenital outcomes, and cost to prevent a case. This analysis, from the perspective of the healthcare sector, included medical case costs expressed in US dollars (1999), discounted at an annual rate of 3%.

RESULTS

Mass treatment was the most cost-effective strategy among women and men. Of the screening strategies for women, universal screening combined with standard practice was the most cost-effective; it was used for treating 499 more cases of gonorrhea and chlamydia than was standard practice, saving $95.70 per case treated. Standard ED practice remained the most cost-effective strategy for men under a variety of circumstances.

CONCLUSION

The authors recommend urine ligase chain reaction screening for gonorrhea and chlamydia in women aged 18 years to 31 years in the ED, in conjunction with standard ED practice, to decrease the occurrence of the sequelae and costs associated with infection.

Effect of endocervical specimen adequacy on ligase chain reaction detection of Chlamydia trachomatis

Several studies have demonstrated that the sensitivity of a commercially available PCR test for the detection of Chlamydia trachomatis (Roche Diagnostics) is affected by the cellular quality of the endocervical swab specimens. The cellular adequacies of 1,633 female endocervical swab specimens were assessed and compared with the results of C. trachomatis detection obtained by ligase chain reaction (LCR; Abbott Laboratories). Specimen adequacy studies and LCR were performed with samples from the same swab, after demonstration of the stability of human epithelial cells in LCR transport medium. Prior to heat treatment of the swab specimen, an aliquot was removed and cytocentrifuged onto a slide. Cell spots were stained and examined at x 400 magnification for endocervical (columnar epithelial or metaplastic) cells and erythrocytes. The overall rate of positivity of the LCR was 6.5% (106 of 1,633 specimens) with pooled specimens (pools of 4 specimens each; reduced cutoff). Of the 1,633 specimens examined, 655 (40.1%) were found to contain one or more endocervical cells. The rate of positivity for C. trachomatis was 10.8% (71 of 655 specimens) among specimens containing endocervical cells, whereas it was 3.6% (35 of 978 specimens) among specimens lacking endocervical cells (P < 0.0001). There was no linear trend between the rate of positivity for C. trachomatis and the number of endocervical cells (P = 0.24). The rate of positivity for C. trachomatis was 5.4% (8 of 147 specimens) among specimens containing large numbers of erythrocytes (> or =100 per high-power field), whereas it was 6.6% (98 of 1,486 specimens) among specimens containing less than 100 erythrocytes per high-power field (P = 0.59). These results show that the sensitivity of the Abbott C. trachomatis LCR test is affected by the presence of endocervical cells. Additionally, they indicate that the presence of a single endocervical cell is as good an indicator of specimen adequacy as the presence of many endocervical cells. The presence of a large number of erythrocytes was not associated with an increased rate of sensitivity of the LCR.

Evaluation of a modified sanitary napkin as a sample self-collection device for the detection of genital chlamydial infection in women

A modified sanitary napkin was compared with endocervical swab and urine specimens for the detection of urogenital Chlamydia trachomatis infection. Endocervical swabs and/or first-catch urine were collected from 510 women at medical or community settings in Quebec City. Participants were also asked to wear a modified sanitary napkin (Ezy-Detek) during 4 consecutive hours and to bring it back to the clinic or mail it to the laboratory. Endocervical and urine specimens were tested using the Cobas Amplicor CT/NG assay (Roche Diagnostic Systems) according to the manufacturer's instructions, as were specimens collected with the napkin after adequate preparation. If the PCR test result was positive on the endocervical sample or on any two samples, a woman was considered to be infected. PCR testing results on paired samples were identical for 493 (96.6%) of 510 women. According to the definition given above, 58 (11.3%; 95% confidence interval [CI], 8.7 to 14.5%) women were infected with C. trachomatis. The sensitivity and specificity of PCR testing on modified sanitary napkin specimens were, respectively, 93.1% (54 of 58; 95% CI, 83.3 to 98.1%) and 98.9% (447 of 452; 95% CI, 97.4 to 99.6%) compared to 81.0% (47 of 58; 95% CI, 68.6 to 90.1%) and 100% (451 of 451; 95% CI, 99.2 to 100%) for urine specimens. The positive and negative predictive values were, respectively, 91.5% (54 of 59) and 99.1% (447 of 451) for the sanitary napkin specimens compared to 100% (47 of 47) and 97.6% (451 of 462) for urine samples. These results suggest that a modified sanitary napkin represents an effective noninvasive device for self-collection of specimens to detect urogenital C. trachomatis infection.

A Nationwide Sentinel Clinic Survey of Chlamydia trachomatis Infection in Finland

BACKGROUND

Chlamydia trachomatis has been recognized as a major sexually transmitted infection in North America and Western Europe during the past two decades. The incidence of C trachomatis in Finland has been continuously high throughout the 1990s.

OBJECTIVES

As the epidemic of C trachomatis infection continues in Finland, there is a need to obtain up-to-date information on the prevalence and patient profiles in the planning of preventive strategies.

METHODS

A nationwide sentinel clinic network consisting of seven sexually transmitted disease (STD) and five general student health clinics was established in 1995. Data were collected during a 3-year period (1995-1997) from 3,686 patients with and 32,230 patients without C trachomatis using a self-administered questionnaire.

RESULTS

The prevalence of chlamydia was 8.4% in the STD clinics and 5.3% in the general clinics; 90% of the infections were endemic. The prevalence was highest in the youngest age group (15-19 years; 16% in females, 14% in males). The patients with chlamydia were significantly younger (mean age: men 26.6 years, women 23.7 years) than those without chlamydia. Women with chlamydia used oral contraceptives or intrauterine devices (IUD) significantly more often (59%) than women without chlamydia (42%). A high number of sex partners and a history of previous chlamydia during the preceding 12 months were also risk factors. Men contracted chlamydia frequently from a casual partner (61%) but rarely from a commercial sex worker (2%). For women, the source partner was most often a regular one (61%). The median time from exposure to attendance was 34 days, and was highest when the source partner was a spouse. One third of the patients could have spread chlamydia to a new partner before the diagnosis.

CONCLUSIONS

C trachomatis infection is spread all over Finland, and the risk factors include younger age, high number of sex partners, and use of oral contraceptives or IUDs. Source partner analysis focused attention on the importance of transmission from regular partners, especially in women. The time from transmission to diagnosis was long, and any effort to shorten this period would be an effective preventive strategy.

Detection of Chlamydia trachomatis and Neisseria gonorrhoeae by enzyme immunoassay, culture, and three nucleic acid amplification tests

The purpose of this study was to evaluate and compare three commercially available nucleic acid amplification tests (NAATs) for the detection of Neisseria gonorrhoeae and Chlamydia trachomatis. Roche PCR and Becton Dickinson strand displacement amplification (SDA) were performed on 733 endocervical swab specimens from commercial sex workers. Abbott ligase chain reaction (LCR) was performed on a subset of 396 samples. Endocervical specimens from all women were also tested by culture for N. gonorrhoeae and by Syva MicroTrak enzyme immunoassay (EIA) for C. trachomatis. A positive N. gonorrhoeae result was defined as a positive result by culture or by two NAATs, and a positive C. trachomatis result was defined as a positive result by two tests. According to these definitions, the sensitivities and specificities for the subsample of 396 specimens of N. gonorrhoeae culture, PCR, SDA, and LCR were 69.8, 95.2, 88.9, and 88.9% and 100, 99.4, 100, and 99.1%, respectively; the sensitivities and specificities of C. trachomatis EIA, PCR, SDA, and LCR were 42.0, 98.0, 94.0, and 90.0% and 100, 98.0, 100, and 98.6%, respectively. The performance characteristics of N. gonorrhoeae culture, PCR, and SDA and C. trachomatis EIA, PCR, and SDA for all 733 specimens were defined without inclusion of LCR results and by discrepant analysis after resolution of discordant N. gonorrhoeae PCR results and of discordant C. trachomatis EIA and PCR results by LCR testing. The sensitivities of N. gonorrhoeae culture, PCR, and SDA before and after LCR resolution were 67.8, 95.7, and 93.9% and 65, 95.8, and 90.0%, respectively. The sensitivities of C. trachomatis EIA, PCR, and SDA decreased from 39.4, 100, and 100% to 38.7, 98.7, and 94.7%, respectively. All three NAATs proved to be superior to N. gonorrhoeae culture and to C. trachomatis EIA. The accuracies of the different NAATs were quite similar. SDA was the only amplification assay with 100% specificity for detection of both N. gonorrhoeae and C. trachomatis in endocervical specimens.

Anorectal manifestations of sexually transmitted infections

Sexually transmitted infections have a wide range of clinical presentations, including involvement of the anal verge, anal canal and rectum. This review focuses on anorectal sexually transmitted infections which may cause diagnostic difficulty when encountered by the coloproctologist. An approach to the diagnosis of a variety of sexually transmitted infections is set out, with a discussion of the role of biopsy and a summary of relevant histopathological findings. The value of early antibiotic treatment is discussed. Problems related to HIV/AIDS are highlighted, as clinical presentation may be atypical in immunosuppressed individuals. Sexually transmitted oncogenic viruses and their role in anal neoplasia are also briefly summarized.

Performance characteristics of the Becton Dickinson ProbeTec System for direct detection of Chlamydia trachomatis and Neisseria gonorrhoeae in male and female urine specimens in comparison with the Roche Cobas System

OBJECTIVE

The Becton Dickinson BDProbeTec ET System is a new semiautomated system using strand displacement amplification technology that simultaneously amplifies and detects Chlamydia trachomatis and Neisseria gonorrhoeae DNA. The strand displacement amplification products are hybridized with a fluorescent detector probe and are captured by a chemiluminescent assay in a microwell format. An amplification control is also included to monitor assay inhibition. This study evaluated the performance of the BDProbTec ET system in detecting C trachomatis and N gonorrhoeae in male and female urine specimens, calculated its ability to process large volumes of specimens, and determined the inhibition rate.

MATERIALS AND METHODS

Eight hundred twenty-five male and 399 female urine specimens were tested for both C trachomatis and N gonorrhoeae with the BDProbeTec ET system, and results were compared with those of the Roche Amplicor Cobas system. All urine specimens were processed on both assays on the same day they were received, according to the manufacturers' instructions. Discrepant results were resolved by in-house polymerase chain reaction assays. Internal or amplification controls were also used in each specimen assay to monitor inhibition. The throughput of the BDProbTec ET system was further tested with 150 urine specimens on an 8-hour shift for 2 days.

RESULTS

The overall sensitivity, specificity, positive predicative value, and negative predicative value for for detection of chlamydia were 95.3%, 99.3%, 95.9%, and 99.2% for strand displacement amplification and 95.9%, 98.3%, 90.6%, and 99.3% for the Roche Amplicor system. For detection of gonorrhea, these values were 100%, 99.7%, 88.2%, and 100% and 96.7%, 98.9%, 69%, and 99.9%, respectively. The overall inhibition rates for both strand displacement amplification and Roche Amplicor were less than 3.5%. The BDProbTec ET system was able to produce 150 results each for chlamydia and gonorrhea and the internal control within the 8-hour shift.

CONCLUSIONS

The performance characteristics of the BDProbeTec ET assay are similar to those of the Roche Amplicor polymerase chain reaction for detection of chlamydia and gonorrhea in male and female urine specimens. The system was able to produce 300 results in an 8-hour shift.

Diagnostic performance of the Roche AMPLICOR PCR in detecting Neisseria gonorrhoeae in genitourinary specimens from female sex workers in Cotonou, Benin

The objective of this study was to evaluate the diagnostic performance of the Roche multiplex AMPLICOR Chlamydia trachomatis/Neisseria gonorrhoeae PCR test for the detection of Neisseria gonorrhoeae infection in female urine specimens and wet and dry endocervical swabs. Endocervical swabs and urine specimens were collected from 342 female sex workers from Cotonou, Benin, and were tested using the AMPLICOR C. trachomatis/N. gonorrhoeae test (Roche Diagnostic Systems, Inc., Branchburg, N.J.) with internal control detection. Endocervical swabs were also cultured on Thayer-Martin medium. A series of alternate standards that included a combination of all the tests but not the test being evaluated was used to assess the performance of the test with each type of specimen. The sensitivity, specificity, and positive and negative predictive values for the urine were 53.8, 98.9, 93.5, and 87.5%, respectively. Corresponding figures for the wet swab were 91.5, 100, 100, and 97.4%, respectively. Those for the dry swab were 96.3, 96.2, 88.5, and 98.8%, respectively. Based on this study, the AMPLICOR PCR assay showed a low sensitivity for detection of N. gonorrhoeae infection in urine specimens, whereas the test was found to be highly sensitive and specific with endocervical specimens.

Low diagnostic accuracy of selective screening criteria for asymptomatic Chlamydia trachomatis infections in the general population

OBJECTIVES

To develop and validate selective screening criteria for asymptomatic Chlamydia trachomatis infections in the general population.

METHODS

11,505 people, aged 15-40 years, registered in 16 general practices in Amsterdam were invited to return by mail a home obtained first void urine sample and a questionnaire. Participants were randomly allocated into a development group (75%) or a validation group (25%). C trachomatis infection was determined by the ligase chain reaction. In the development group a set of criteria was identified by means of stepwise logistic regression analysis. The diagnostic accuracy (area under the ROC curve; AUC) and sensitivity, and the corresponding percentage of people selected for screening were calculated. The criteria developed in this study were applied to the validation group.

RESULTS

The prevalence of asymptomatic C trachomatis infections among men was found to be 2.4% (1.7-3.0), and among women 2.8% (2.2-3.4). Screening men, based on Surinam/Antillean origin and painful micturition, yielded an AUC of 0.58 (0.55-0.60). Screening women, based on Surinam/Antillean origin, new sex partner in the previous 2 months, and unmarried/not cohabiting, yielded an AUC of 0.67 (0.65-0.69). Application of the criteria for men to the validation group yielded an AUC of 0.53 (0.48-0.57); by screening 10% of the men, 15% of the cases were detected. The AUC of the criteria for women in the validation group was 0.58 (0.54-0.61); by screening 51% of the women, 63% of the cases were detected.

CONCLUSION

The prevalence of asymptomatic C trachomatis infections in Amsterdam is less than 3%. No suitable selective screening criteria for the general population could be identified.

Multicenter evaluation of AMPLICOR and automated COBAS AMPLICOR CT/NG tests for Neisseria gonorrhoeae

The fully automated COBAS AMPLICOR CT/NG and semiautomated AMPLICOR CT/NG tests were evaluated in a multicenter trial for their ability to detect Neisseria gonorrhoeae infections. Test performance compared to that of culturing was evaluated for 2,192 matched endocervical swab and urine specimens obtained from women and for 1, 981 matched urethral swab and urine specimens obtained from men. Culture-negative, PCR-positive specimens that tested positive in a confirmatory PCR test for an alternative target sequence within the N. gonorrhoeae 16S rRNA gene were considered to be true positives. The overall prevalences of gonorrhea were 6.6% in women and 20.1% in men. The COBAS AMPLICOR and AMPLICOR formats yielded concordant results for 98.8% of the specimens and exhibited virtually identical sensitivities and specificities. The results that follow are for the COBAS AMPLICOR format. With the infected patient as the reference standard, the resolved sensitivities of PCR were 92.4% for endocervical swab specimens and 64.8% for female urine specimens. There were no significant differences in these rates between women with and without symptoms. Among symptomatic men, COBAS AMPLICOR sensitivities were 94.1% for urine and 98.1% for urethral swabs; for asymptomatic men, the results were 42.3 and 73.1%, respectively. In comparison, the sensitivities of culturing were 84.8% for endocervical specimens, 92.7% for symptomatic male urethral specimens, and only 46.2% for urethral specimens obtained from asymptomatic men. When PCR 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 99.5% for endocervical swab specimens, 99.8% for female urine specimens, 98.9% for male urethral swab specimens, and 99.9% for male urine specimens. The internal control revealed that 2.1% of specimens were inhibitory when initially tested. Nevertheless, valid results were obtained for 99.2% of specimens because 60.0% of the inhibitory specimens were not inhibitory when a second aliquot was tested. The COBAS AMPLICOR CT/NG test for N. gonorrhoeae exhibited high sensitivity and specificity with urethral swab and urine specimens from men and endocervical swab specimens from women and thus is well suited for diagnosing and screening for N. gonorrhoeae infection.

The role of DNA amplification technology in the diagnosis of infectious diseases

Nucleic acid amplification and detection methods developed in the past decade are useful for the diagnosis and management of a variety of infectious diseases. The most widely used of these methods is the polymerase chain reaction (PCR). PCR assays can detect rapidly and accurately the presence of fastidious and slow-growing microorganisms, such as Chlamydia, mycoplasmas, mycobacteria, herpesviruses and enteroviruses, directly from clinical specimens. Commercial PCR assays for the diagnosis of tuberculosis and genital C. trachomatis infection are now routinely used in many diagnostic laboratories. Assays have also been developed that can detect antimicrobial resistance and are used to identify the cause of infection by organisms that cannot be cultivated. The value of viral load measurement by nucleic acid amplification in the management of patients with HIV infection or hepatitis C has also been well established. However, evaluations of this technology for rapid microbial diagnosis have generally been limited by small samples, and the cost of these assays may be as high as Can$125 per test. As nucleic acid amplification methods continue to evolve, their role in the diagnosis and management of patients with infectious diseases and their impact on clinical outcomes will become better defined.

Reproducibility problems with the Abbott laboratories LCx assay for Chlamydia trachomatis and Neisseria gonorrhoeae

This study demonstrates that significant reproducibility problems can occur during routine use of the Abbott Laboratories LCx assay for Chlamydia trachomatis and Neisseria gonorrhoeae. These problems can go undetected by the quality control procedures outlined in the manufacturer's package insert. We outline here procedures for detecting and preventing contamination and reproducibility problems.

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.

Evaluation of patient-administered tampon specimens for Chlamydia trachomatis and Neisseria gonorrhoeae

BACKGROUND

The patient-administered tampon specimen has proven to be an easy and sensitive method for the diagnosis of genital Chlamydia trachomatis and Neisseria gonorrhoeae infections in women by polymerase chain reaction (PCR). This method avoids the need for endocervical sampling and stringent criteria for transport.

GOAL

To evaluate two commercial amplification systems for the detection of C trachomatis and N gonorrhoeae from tampon specimens.

STUDY DESIGN

A group of 400 positive and negative tampon specimens tested by an in-house PCR method were selected from a pool of more than 2,000 previously collected tampons. Overall, 93 C trachomatis-positive and 77 N gonorrhoeae-positive specimens were evaluated. Each specimen was tested by Roche Cobas Amplicor and Abbott LCx (LCR), and results were compared to the in-house PCR method.

RESULTS

Detection of C trachomatis by both assays was not significantly different from the in-house PCR assay. Fewer tampons were positive for N gonorrhoeae by LCR than either the in-house assay (P = 0.0001) or by Roche Amplicor (P = 0.01). However, tampon specimens tested by Roche Amplicor required DNA extraction to achieve comparative sensitivity.

CONCLUSION

Both commercial assays can be applied to tampon-collected specimens for automated detection of sexually transmitted diseases. The detection of C trachomatis was similar to the in-house PCR test for both assays (P = 0.73, 0.68). Detection of N gonorrhoeae resulted in fewer positive tampon specimens when tested by ligase chain reaction than both Roche Amplicor and in-house PCR.

The Use of Molecular Techniques for the Diagnosis and Epidemiologic Study of Sexually Transmitted Infections

Molecular diagnostic tests are more sensitive and, in many cases, more specific than conventional laboratory methods for the detection of sexually transmitted infections. Here, we review recently developed molecular methods for the diagnosis and subtyping of the most common sexually transmitted infections: infections caused by Chlamydia trachomatis, Neisseria gonorrhoeae, human papillomavirus, Trichomonas vaginalis, and the agents of genital ulcer disease (Haemophilus ducreyi, herpes simplex virus, Treponema pallidum, and Calymmatobacterium granulomatis). We also provide an overview of the laboratory diagnostic tests and clinical specimens to use when infection with these agents is suspected.

Determination of Chlamydia trachomatis prevalence in an asymptomatic screening population: performances of the LCx and COBAS Amplicor tests with urine specimens

This study determined the performances of the LCx (Abbott) and COBAS Amplicor (Roche) tests with urine specimens for the detection of Chlamydia trachomatis in an asymptomatic screening population. Randomly selected women and men (age range, 15 to 40 years) registered in 20 general practices in Amsterdam, The Netherlands, were invited to participate in this study. Urine specimens (n = 2, 906; 1,138 specimens from men and 1,717 specimens from women) were tested for C. trachomatis by the COBAS Amplicor (Roche) and LCx (Abbott) tests. Samples which were positive by only one assay were subjected to discrepant analyses by a third assay (in-house plasmid PCR). By the LCx assay C. trachomatis DNA was detected in urine specimens from 46 of 1,717 women and 29 of 1,138 men, while the COBAS Amplicor detected C. trachomatis DNA in 52 and 35 specimens, respectively. When comparing the LCx and COBAS Amplicor tests, 32 test results (20 for women and 12 for men) were discrepant. After discrepant analyses the following sensitivities, specificities, and positive predictive values were found for the LCx and COBAS Amplicor tests: 78.6 versus 98.8%, 99.7 versus 99.9%, and 88.0 versus 95.4%, respectively. No prominent differences were found between men and women with regard to the test performances. After discrepant analyses the overall prevalences of C. trachomatis in women and men were 3.0 and 2.8%, respectively. For both women and men the prevalence in the younger age groups was higher than that in the older age groups. In conclusion, the COBAS Amplicor tests shows better diagnostic characteristics than the LCx assay for the detection of C. trachomatis in urine specimens from an asymptomatic screening population. In this asymptomatic population the overall prevalence of C. trachomatis was 2.9%.

New developments in diagnosis and management of adolescents with sexually transmitted disease

The battle against the epidemic of sexually transmitted infections continues but the clinician has new diagnostic and therapeutic weapons. This manuscript reviews new technologies, as well as novel applications of newer methodologies, such as utilization of amplified DNA techniques for urine specimens or patient-collected specimens. Newest treatment recommendations are also reviewed.

Detection of Chlamydia trachomatis endocervical infections by ligase chain reaction versus ACCESS Chlamydia antigen assay

Ligase chain reaction (LCR) was compared with ACCESS immunoassay for detection of chlamydial infections in females. Despite efforts to improve ACCESS performance by evaluation of specimens that were in the test performance "grey zone," LCR remained more sensitive and was less expensive to perform. ACCESS had a sensitivity of 83.9%, a specificity of 99.7%, a positive predictive value of 96.3%, and a negative predictive value of 98.5%.