Effect of blind passage and multiple sampling on recovery of Chlamydia trachomatis from urogenital specimens

Diagnostic tests and specimens used to screen for Chlamydia trachomatis in genitourinary medicine clinics in the United Kingdom

This questionnaire study looked at the diagnostics tests and specimens used to screen for Chlamydia trachomatis in UK genitourinary medicine (GUM) clinics. Replies were received from 70% (185/265) of clinics. Half used only one site to screen women. One-third took anal swabs from patients who had anal sex and 10% took oropharyngeal swabs from patients who had oral sex.

Immunoassays were used to screen men for chlamydia in 86% of the clinics and women in 88%. Only 60% of male and 62% of female immunoassays were supplemented by a second test. Six per cent of clinics used molecular technique (MT) to screen men and 4% to screen women and 4% were trying to acquire it.

Culture was not available to 58% of clinics. MT was not available to 81%, 89% of which was due to non provision locally and/or cost. Only 7% of clinicians thought that using MT for screening was unnecessary. There were significant differences in the availability of the technique between large academic and small clinics. A national review of GUM strategies to screen for C. trachomatis with adequate funding is urgently needed.

Role of STAT1 in Chlamydia-Induced Type-1 Interferon Production in Oviduct Epithelial Cells

We previously reported that Chlamydia muridarum-infected murine oviduct epithelial cells (OE cells) secrete interferon β (IFN-β) in a mostly TLR3-dependent manner. However, C. muridarum-infected TLR3-deficient OE cells were still able to secrete detectable levels of IFN-β into the supernatants, suggesting that other signaling pathways contribute to Chlamydia-induced IFN-β synthesis in these cells. We investigated the role of STAT1 as a possible contributor in the Chlamydia-induced type-1 IFN production in wild-type (WT) and TLR3-deficient OE cells to ascertain its putative role at early- and late-times during Chlamydia infection. Our data show that C. muridarum infection significantly increased STAT1 gene expression and protein activation in WT OE cells; however, TLR3-deficient OE cells showed diminished STAT1 protein activation and gene expression. There was significantly less IFN-β detected in the supernatants of C. muridarum-infected OE cells derived from mice deficient in STAT1 when compared with WT OE cells, which suggest that STAT1 is required for the optimal synthesis of IFN-β during infection. Real-time quantitative polymerase chain reaction analyses of signaling components of the type-1 IFN signaling pathway demonstrated equal upregulation in the expression of STAT2 and IRF7 genes in the WT and TLR3-deficient OE cells, but no upregulation in these genes in the STAT1-deficient OE cells. Finally, experiments in which INFAR1 was blocked with neutralizing antibody revealed that IFNAR1-mediated signaling was critical to the Chlamydia-induced upregulation in IFN-α gene transcription, but had no role in the Chlamydia-induced upregulation in IFN-β gene transcription.

[Chlamydia trachomatis in women]

The authors present results of a planned prospective study of infections with Chlamydia trachomatis in women. Direct immunofluorescence test (DIF) for proving Chlamydia trachomatis antigens in endocervical smear (by means of monoclonal antibodies), ELISA test for proving IgG antibodies against Chlamydia trachomatis in sera and RVK method for proving antibodies against group Chlamydia-antigen were applied to test 288 women (aged 19-67), previously thoroughly anamnestically and clinically examined Chlamydia trachomatis infection was found in 29.51% of the cases, equally distributed in all age groups. The authors analyzed frequency of Chlamydia positive findings according to clinical diagnoses, parity, relevant data from gynecological history, as well as results of vaginal secretion tests and Papanicolaou smear findings.

Should we consider alternatives to combined cervical and urethral swabs for detection of Chlamydia trachomatis in females?

BACKGROUND

The optimum approach for detecting Chlamydia trachomatis (CT) is considered to be combined cervical and urethral testing.

OBJECTIVE

To assess the contribution of female urethral swabs in CT diagnosis and to examine alternatives.

METHOD

Urethral and endocervical samples for CT were performed on 757 sexually active female patients, >16 years, attending the genitourinary medicine clinic at Macclesfield District General Hospital from October 2005 to November 2006. Swabs were collected and transported to the laboratory in separate AC2 sample collection tubes and were tested by AC2 assay.

RESULTS

Of the 757 patients tested simultaneously by both endocervical and urethral swab, a total of 90 had CT identified by either method giving a positivity rate of 11.9%. Results for urethral and endocervical swabs were concordant in 77 patients (85.6%). Eighty two infections (91.1%) would have been diagnosed by swabbing the cervix only but an additional 8 (8.9%) were picked up by urethral swab. Urethral symptoms had been mentioned by 1 of these 8 women.

CONCLUSION

8.9% infected women were positive only on urethral swab. One of these would have been picked up owing to presenting symptoms, hence reducing the extra yield to 7.8% and leaving only 7 positives on 757 urethral swabs with a detection rate of 1% of all urethral swabs. Considering the low yield and the discomfort of urethral swabbing, an additional urethral swab appears unwarranted on grounds of both cost and patient care. As a small number of cases were detected at the urethra but not the cervix, it may be worthwhile investigating the performance of AC2 when placing an endocervical swab in first catch urine. An effective and simpler approach may be a switch to testing vaginal swabs by AC2.

Chlamydia trachomatis load at matched anatomic sites: implications for screening strategies

Urethral and endocervical swabs and self-collected vaginal swabs (SCVSs) and urine specimens are all used as samples for diagnosis of urogenital infection with Chlamydia trachomatis. We have now determined chlamydial organism load in matched specimens from different anatomic sites and examined its relation to clinical signs and symptoms in men and women. Organism load was measured with assays based on the ligase chain reaction or real-time PCR analysis. The mean organism loads in 58 infected men were 1,200 and 821 elementary bodies (EBs) per 100 microl of sample for first-void urine (FVU) and urethral swabs, respectively (P>0.05). Organism load in FVU samples or urethral swabs was positively associated with symptoms (P<0.01) and clinical signs (P<0.01) in men. The mean organism loads in 73 infected women were 2,231, 773, 162, and 47 EBs/100 microl for endocervical swabs, SCVSs, urethral swabs, and FVU samples, respectively (P<0.001 for each comparison). Only the presence of multiple symptoms or clinical signs was associated with organism load in women. These results show that FVU is a suitable noninvasive sample type for men, given the fact that its chlamydial load did not differ significantly from that of urethral swabs. Given their higher organism load compared with FVU, SCVSs are the preferred noninvasive sample type for women.

Chlamydial infections in urology

Chlamydia trachomatis is the most frequent cause for sexually transmitted diseases in European countries. The organism has an intracellular habitat with a very specific life cycle. A variety of diagnostic tests have been developed with different sensitivity and specificity. Interpretation of these tests can sometimes be difficult. Diseases caused by C. trachomatis in men comprise urethritis, prostatitis, epididymitis, infertility and reactive arthritis. Especially in prostatitis, the exact role of C. trachomatis is still under debate for the technical difficulties localizing the pathogen to the prostate. For treatment, only some antibiotics are effective because of the intracellular habitat of the pathogen. Prevention of infection comprises treatment and screening efforts.

[Chlamydia trachomatis urogenital infections in women. Best diagnostic approaches]

Chlamydiae are obligate intracellular bacteria. Chlamydia trachomatis is the most common sexually transmitted disease (STD). The C. trachomatis damaging disease sequelae such as sterility is based on intense and chronic inflammation elicited and maintained by reinfection or persistent infection. The high prevalence of C. trachomatis infection reflects the long and successful adaptation of these organisms to persist in their human host population. The large group of asymptomatically infected persons is not only at risk of serious long-term sequelae but also sustains transmission within communities. C. trachomatis acute infections have been diagnosed by cell culture, direct immunofluorescence, enzyme immunoassay, direct DNA hybridization, and more recently by nucleic acid amplification tests (NAATs). In chronic or persistent chlamydial infections, the level of Chlamydia is very low and bacteria are often not viable. Such infections would be characterized by continuing positive NAATs but only intermittent isolation of viable Chlamydia and positive assays for chlamydial protein antigen. The development of NAATs has been a major advance in the field of chlamydial diagnosis. The use of NAATs associated with serology test is the best diagnosis. The introduction of assays based on amplification of genetic material has subsequently increased the sensitivity of detecting chlamydial infections and offers the opportunity to use non-invasive sampling techniques to screen for infections in asymptomatic subjects. In this article, it was proposed the best diagnosis approaches for detection of acute and chronic infections.

Use of multiple nucleic acid amplification tests to define the infected-patient "gold standard" in clinical trials of new diagnostic tests for Chlamydia trachomatis infections

Nucleic acid amplification tests (NAATs) can be used to define the infected-patient "gold standard" for the purpose of designing studies of the performance of Chlamydia trachomatis diagnostic tests. It is unclear how many test results run by different NAATs and what combinations of specimens comprise the best infected-patient gold standard. We approached this question with data from a large study of the performance of a new NAAT. Data were available from three endocervical swabs and a urine specimen collected from each of 1,412 women and tested by three different NAATs. Results from all three assays were used equally in a rotating fashion to define the infected-patient gold standard. Multiple different infected-patient gold standards for estimating swab and urine specimen sensitivity and specificity for one NAAT method were created by varying the number and combinations of swab and urine comparator results with two different NAATs, The effect of changing the infected-patient gold standard definition was determined by constructing receiver-operator-like curves with calculated sensitivities and specificities for each test. The one-positive-of-two-results or two-positive-of-two-results (same or two different assays) infected-patient gold standard definitions produced low sensitivity and low specificity estimates, respectively. If four comparator NAAT results were used, the any-three-positive-of-four-results definition or the at-least-one-specimen-positive-by-each-of-two-comparator-assays definition appeared to provide better combinations of sensitivity and specificity estimates. The any-two-positive-out-of-three-results definition resulted in estimates that were as good as produced with the former two definitions. This analytic approach provides a means of clearly visualizing the effects of changing NAAT-based infected-patient gold standards and should be helpful in designing future studies of new C. trachomatis diagnostic tests.

Is there a role for Chlamydia pneumoniae in hemodialysis vascular access thrombosis?

Significant evidence suggests that Chlamydia pneumoniae has a major role in occlusive vascular disease. Vascular access thrombosis in chronic hemodialysis patients is a frequent problem; the underlying pathological state is stenosis caused by endothelial hyperplasia. There is presently no literature concerning C pneumoniae in vascular access thrombosis. We embarked on a study to evaluate the possible role of C pneumoniae in access failure. Ten consecutive patients with thrombosed polytetrafluoroethylene (PTFE) conduit arteriovenous fistulae undergoing surgical thrombectomy and revision were studied. We sought to detect C pneumoniae using both culture and polymerase chain reaction (PCR) methods. An excisional biopsy of the stenotic vein segment just above the anastomosis with the PTFE graft was obtained at surgery. Vein samples weighing at least 30 mg were aseptically placed in transport media and stored at 4 degrees C for up to 24 hours. The samples then were sonicated, inoculated in Hep-2 cell culture vials containing confluent monolayers, and passaged three times over 2 weeks. Detection was by direct fluorescent antibody staining. Both culture and PCR were performed in an active chlamydia research laboratory. None of the 10 samples was positive for C pneumoniae by culture or PCR. Based on our preliminary pilot study, we do not believe C pneumoniae has a major role in endothelial hyperplasia and consequent graft loss in the hemodialysis patients we studied.

Comparison of the effectiveness of polymerase chain reaction and enzyme immunoassay in detecting Chlamydia trachomatis in different female genitourinary specimens

BACKGROUND

In high-volume laboratories, enzyme immunoassay (EIA) is the most commonly used method of detecting Chlamydia trachomatis. The optimal specimen for detecting C trachomatis is a combined urethral and cervical swab.

OBJECTIVE

To compare EIA with the combined urethral and cervical swab with polymerase chain reaction (PCR) on urine alone and urine mixed with cervical cells.

PATIENTS AND METHODS

Phase 1 of the study included 752 sets of specimens used for comparison. In phase 2, another 212 samples of urine and urine plus cervical cells were added to the study for comparison of the 2 specimen types using PCR.

RESULTS

In phase 1, 648 samples were negative and 76 were positive by all 3 methods and specimen combinations. Enzyme immunoassay was able to detect 81 positive samples (10.8%), whereas PCR on urine alone detected 97 positive samples (12.9%) and PCR on urine plus cervical cells detected 102 positive samples (13.6%), giving a sensitivity of 75%, 93.3%, and 98. 1% respectively. In phase 2, PCR on urine alone detected 119 positive samples (12.3%) and PCR on urine plus cervical cells detected 127 positive samples (13.1%), with a sensitivity of 92.2% and 98.5%, respectively.

CONCLUSION

Polymerase chain reaction on urine alone or urine plus cervical cells is superior to EIA on combined cervical and urethral swabs. There is a slight advantage of adding cervical cells to the urine compared with the urine specimen alone when PCR is used as the assay for detection. The total inhibition rate in our female population is only 3.1% when PCR is used.

Phylogenetic analysis of the Chlamydia trachomatis major outer membrane protein and examination of potential pathogenic determinants

Phylogenetic analysis was utilized to investigate biological relationships (tissue tropism, disease presentation, and epidemiologic success), as evidenced by coevolution, among human strains of Chlamydia trachomatis. Nucleotide sequences of omp1, the gene encoding the major outer membrane protein (MOMP) of C. trachomatis, were determined for 40 strains representing 11 serovars. These data were combined with available omp1 sequences from GenBank for an analysis encompassing a total of 69 strains representing 17 serovars infecting humans. Phylogenetic analysis of the nucleotide and inferred amino acid sequences showed no evolutionary relationships among serovars that corresponded to biological or pathological phenotypes (tissue tropism, disease presentation, and epidemiologic success). In addition, no specific residues that may have evolved to play a role in determining biologically relevant characteristics of chlamydia, such as tissue specificity, disease presentation, and epidemiologic success, were apparent in the MOMP. These results suggest that variation in MOMP may have arisen from a need to be diverse in the presence of immune pressure rather than as a function of pathogenicity. Therefore, the role of MOMP in disease pathogenesis and infection may be passive, and it may not be the major ligand responsible for directing infection of various human cell types.

Evaluation of the microparticle enzyme immunoassay Abbott IMx Select Chlamydia and the importance of urethral site sampling to detect Chlamydia trachomatis in women

OBJECTIVE

To evaluate the commercial microparticle enzyme immunoassay (MEIA), Abbott IMx Select Chlamydia, for the detection of Chlamydia trachomatis in women and to compare its performance with endocervical cell culture. Also, to determine whether sampling the urethral site is an important part of chlamydial diagnosis in women.

SETTING

The Auckland, Manukau, and Waitakere Sexual Health Clinics, Auckland, New Zealand and the Department of Clinical Microbiology, Auckland Hospital, Auckland, New Zealand.

PATIENTS

The study population consisted of 622 consecutive women who attended the three sexual health clinics.

METHODS

The IMx Chlamydia assay was performed on an IMx analyser, following a specimen treatment procedure. All reactive samples from the IMx Chlamydia assay were confirmed using the IMx Chlamydia blocking antibody reagent. The Syva direct fluorescent antibody (DFA) test was used to aid in resolving discrepancies. The cell culture technique was performed in shell vials using cycloheximide treated McCoy cells, which were stained using a fluorescein conjugated monoclonal antibody.

RESULTS

When compared against the endocervical cell culture, the IMx Chlamydia had a sensitivity of 82.1% (23/28) and a specificity of 99.3% (590/594). When compared against an expanded gold standard, the IMx Chlamydia and endocervical cell culture had sensitivities of 84.4% (27/32) and 87.5% (28/32), specificities of 100% (590/590) and 100% (590/590), positive predictive values of 100% (27/27) and 100% (28/28), negative predictive values of 99.2% (590/595) and 99.3% (590/594), and accuracies of 99.2% (617/622) and 99.4% (618/622), respectively. The prevalence rate by endocervical cell culture and the expanded gold standard were 4.5% and 5.1%, respectively. Additional urethral cell culture testing revealed a further nine patients positive from this site only, giving a 28% (9/32) increase in the number of patients diagnosed for chlamydia, thus giving an overall prevalence of 6.6% (41/622).

CONCLUSIONS

The IMx Chlamydia assay is an easy and rapid test to perform, it is cost effective, and shows similar performance to endocervical cell culture in the female population studied and is thus an excellent alternative to culture for the diagnosis of C trachomatis. The study also showed the importance of urethral site sampling in these women, as endocervical testing alone will underestimate the prevalence of chlamydial genital infection.

Validity of self-reported sexual behaviors in adolescent women using biomarker outcomes

OBJECTIVES

To determine the criterion-related validity of alternative approaches to the measurement of sexual intercourse using sexually transmitted diseases (STD) as a biomarker (the criterion).

STUDY DESIGN

Analyses are based on an urban sample of 255 adolescent women, 15 to 19 years of age, treated for genitourinary infections with Neisseria gonorrhoeae, Chlamydia trachomatis or Trichomonas vaginalis who returned 3 months later for reexamination. Subjects completed self-administered questionnaires at enrollment and at 3 months. Genitourinary cultures were obtained at enrollment, 2 to 4 weeks later at a test-of-treatment visit (TOT), and at 3 months.

RESULTS

Two hundred fourteen of the 255 adolescents also returned for a TOT culture; 186 of these 214 (73%) were free of infection 2 to 4 weeks after enrollment and 30% (56/186) acquired a subsequent STD by 3 months. The validity of questions about sexual behavior differed. No adolescent who denied interim intercourse by reporting "0" sexual partners or "0" coitions acquired an interval STD. Adolescents who denied regular intercourse (vaginal sex) or failed to indicate the number of interim coitions were at high risk for new STD-23% and 21%, respectively. A new measure of sexual intercourse using both the number of sexual partners and the number of coitions contained no missing data; adolescents classified as not having had interim sexual intercourse were free of infection at 3 months, whereas 32% of those who reported intercourse acquired an interim infection.

CONCLUSIONS

These data suggest that high-risk urban adolescent women can accurately report whether they have engaged in vaginal intercourse. The validity of the report appears sensitive to the wording and content of the questions.

Chlamydia trachomatis in adolescents: a review

Genital infections caused by Chlamydia trachomatis represent the most prevalent bacterial sexually transmitted disease in the United States. An estimated 3-4 million cases annually necessitate the expenditure of more than $2 billion in health care costs per year. The ramifications of infection with this organism have significant reproductive complications. The objective of this paper is to provide the reader with a review of Chlamydia trachomatis in general with particular focus on those areas that are pertinent to the adolescent population. The authors hereby provide an overview of the clinically pertinent microbiology, epidemiology, risk factors, selective screening protocols, diagnostic methods, clinical manifestations, and sequelae of C. trachomatis.

The effect of polyethylene glycol (PEG) on the isolation of Chlamydia trachomatis in H-1 HeLa cells

One hundred and ninety-six urethral and endocervical swabs were processed for isolation of C. trachomatis, using H-1 HeLa cells on shell vials, in the presence and absence of 7% PEG in the chlamydial overlay medium. The results were divided into three evaluable groups based on the number of inclusions per coverslip in the shell vials without PEG. The number of inclusions were compared with that of PEG-treated cultures using the paired t-test. The ranges for the three evaluable groups were one to ten, 11-100 and 101-1000 inclusions per coverslip. All three groups showed a significant increase (2.8- to 3.8-fold) in the number of inclusion bodies in the PEG-treated cultures compared to the untreated cultures.

Current methods of laboratory diagnosis of Chlamydia trachomatis infections

Infections caused by Chlamydia trachomatis are probably the most common sexually transmitted diseases in the United States. Commonly unrecognized and often inadequately treated, chlamydial infections can ascend the reproductive tract and cause pelvic inflammatory disease, which often results in the devastating consequences of infertility, ectopic pregnancy, or chronic pelvic pain. C. trachomatis infections are also known to increase the risk for human immunodeficiency virus infection. The obligate intracellular life cycle of C. trachomatis has traditionally required laboratory diagnostic tests that are technically demanding, labor-intensive, expensive, and difficult to access. In spite of these historical challenges, however, laboratory diagnosis of C. trachomatis has been a rapidly advancing area in which there is presently a wide array of commercial diagnostic technologies, costs, manufacturers. This review describes and compares the diagnostic methods for C. trachomatis infection that are currently approved for use in the United States, including the newest DNA amplification technologies which are yet to be licensed for commercial use. Issues to consider in selecting a test for purposes of screening versus diagnosis based on prevalence, performance, legal, social, and cost issues are also discussed.

Declining prevalence of chlamydial infection among adolescent girls

BACKGROUND AND OBJECTIVES

Chlamydial control programs that identify and treat infected persons have been used as a means of reducing prevalence and morbidity. The overall objective of the current study was to examine the prevalence of chlamydial infection during the course of such a program.

GOALS

To determine whether a reduction in isolation rates was evident among adolescent girls during the 8.75 years that the control program has been in place.

STUDY DESIGN

The study population consisted of all 4,329 sexually active girls between the ages of 13 and 19 attending the four adolescent health clinics in Indianapolis, Indiana, during the period beginning October 1, 1985, and ending June 30, 1994. All girls were cultured for Chlamydia trachomatis, and behavioral data were collected for those attending the clinics before 1989. The trend in quarterly isolation rates was examined using linear regression analysis.

RESULTS

Results showed that there was a significant decrease (P = 0.0001), from 25.9% to 9.7%, in the first-visit chlamydial isolation rate over the study period. Behavioral data showed decreases in the frequency of sexual intercourse and in lifetime years of sexual activity, as well as an increase in condom use.

CONCLUSIONS

The quarterly isolation rates showed that there has been a 63% decline in chlamydial infection among adolescent girls attending the clinics for the first time.

Behavioral intervention to increase condom use among high-risk female adolescents

OBJECTIVE

To determine whether condom use among high-risk female adolescents could be increased by a behavioral intervention, with the use of infection with Chlamydia trachomatis as a biomarker of condom practices.

DESIGN

Prospective, randomized, controlled intervention.

SETTING

Urban family planning and sexually transmitted disease clinics.

PARTICIPANTS

Two hundred nine female adolescents, aged 15 through 19 years, who were treated for C. trachomatis genitourinary infection, were randomly assigned to standard (control) or experimental (behavioral intervention) groups. One hundred twelve subjects returned for follow-up 5 to 7 months after enrollment and comprise the study subjects.

MEASUREMENTS

Subjects completed a multiinstrument questionnaire measuring sexual behavior, condom practices, attitudes and beliefs, cognitive complexity, sociodemographics, and motivation at enrollment and follow-up. Endourethral and endocervical sites were sampled for C. trachomatis.

RESULTS

Among the 112 subjects who returned for repeated examination, those who had received the experimental intervention reported increased use of condoms by their sexual partners for protection against sexually transmitted diseases (odds ratio = 2.4; p = 0.02) and for vaginal intercourse (odds ratio = 3.1; p = 0.005) at the 6-month follow-up. Multivariable logistic regression analysis controlling for condom use at enrollment demonstrated that the experimental intervention (odds ratio = 2.8; p = 0.03) and the higher cognitive complexity (odds ratio = 4.6; p = 0.02) independently contributed to greater condom use at follow-up. Despite greater use of condoms among the group who had received the intervention, use remained inconsistent and rates of reinfection with C. trachomatis were not significantly different (26% vs 17%; p = 0.3).

CONCLUSION

Although a brief behavioral intervention among high-risk female adolescents can increase condom use by their sexual partners, incident infection does not appear to be reduced, because condom use remained inconsistent.

Comparison of the ligase chain reaction with cell culture for the diagnosis of Chlamydia trachomatis infection in women

OBJECTIVE

To determine the sensitivity and specificity of ligase chain reaction (LCR) analysis of cervical and urine specimens from women compared with cell culture of cervical and urethral specimens for the diagnosis of genitourinary chlamydial infection.

METHODS

Women (n = 624) attending the Genitourinary Medicine Clinic at University College London Hospitals, were enrolled. Patients who had received antibiotics within the previous two weeks were excluded. Specimens were obtained from the urethra and cervix for chlamydial culture, and from the cervix for LCR. A specimen of first void urine was also obtained for LCR. Discrepancies were resolved by direct immunofluorescence or a major outer membrane protein targeted LCR, or both.

RESULTS

The prevalence of Chlamydia trachomatis in 600 patients, using an expanded standard of a positive cell culture or two confirmed positive non-culture tests, was 13.2% (79/600). Cervical culture detected 68.4% and urethral culture 62% of all positive results compared with 81% detected by cervical LCR and 69% by urine LCR. Cervical and urethral culture combined detected 87.3% whereas cervical and urine LCR combined detected 91.1% of positive cases. Specificity of LCR was 100% in the cervix and 99.8% in urine.

CONCLUSION

This study demonstrates that LCR analysis of cervical and urine specimens is a reliable method for the diagnosis of chlamydial genital infection in women. However, the study also demonstrates that no single test will detect all chlamydial infections. Conventional non-culture tests and cell culture may grossly underestimate the prevalence of chlamydial infection. LCR analysis of a cervical specimen was superior to conventional cell culture without blind passage as a single test for diagnosing chlamydial infection in women, followed by LCR of a urine specimen.

Rapid antigen detection assay for identification of Chlamydia trachomatis infection

A rapid antigen detection test was compared with direct fluorescent-antibody staining and with tissue culture isolation for the detection of Chlamydia trachomatis infections in 507 women. The sensitivities observed were 75, 76, and 84%, respectively, with specificities of > 99%.

Diagnosis of Chlamydia trachomatis genitourinary infection in women by ligase chain reaction assay of urine

Genitourinary infection with Chlamydia trachomatis is a common and potentially serious sexually transmitted disease. Diagnosis of C trachomatis infection in women typically relies on culture of endocervical swabs, an invasive and expensive procedure. The ligase chain reaction (LCR) is an in-vitro nucleic acid amplification technique that exponentially amplifies selected DNA sequences. We have compared an LCR-based assay to detect C trachomatis plasmid DNA in first void urine with culture of endocervical swabs for matched specimens from 1937 women from four geographic regions. Discordant specimen pairs were further tested by direct fluorescent antibody staining for elementary bodies and an alternative LCR assay based on the chlamydial outer membrane protein gene. An "expanded gold standard" was defined to include all culture-positive as well as culture-negative, confirmed LCR-positive women. The sensitivity and specificity of the LCR assay with first void urine samples compared with the expanded gold standard were 93.8% and 99.9%, respectively; the corresponding values for culture were 65.0% and 100%, respectively. Thus, an automated LCR assay of readily obtained urine samples showed a detection rate for infected women almost 30% greater than that of endocervical swab culture. The LCR assay was highly effective for the detection of C trachomatis in urine from women with or without signs or symptoms of chlamydial genitourinary tract infection.

Chlamydia trachomatis infection in a high-risk population: comparison of polymerase chain reaction and cell culture for diagnosis and follow-up

A study to compare the polymerase chain reaction (PCR) test with the cell culture method in diagnosing urogenital Chlamydia trachomatis infections was performed. From 497 patients (212 women, 285 men) attending an outpatient clinic for sexually transmitted diseases, a total of 814 samples (female patients, cervix and urethra; male patients, urethra) were collected. This total included follow-up samples from 35 women and 35 men positive for C. trachomatis by cell culture and/or PCR test, which were collected 2 weeks after treatment with doxycycline (two 100-mg doses per day for 7 days). The PCR test was performed directly on clinical samples without performing phenol-chloroform extraction and ethanol precipitation of DNA. The prevalence of C. trachomatis as measured by positive cell culture was 64 of 497 (12.9%) for all patients, 31 of 212 (14.6%) for women, and 33 of 285 (11.6%) for men. The prevalences as measured by positive PCR test were 71 of 497 (14.3%), 36 of 212 (17.0%), and 35 of 285 (12.3%), respectively. The sensitivities of the cell culture and the PCR test compared with that of true-positive samples were 77.5 to 78.4% and 99.0 to 100.0%, respectively. Discrepancies between cell culture and the PCR test were found for 23 of 497 patients (4.9%), 19 of 212 females (9.0%), and 4 of 285 males (1.4%). Nineteen pretreatment samples from 19 patients (4 female endocervical, 13 female urethral, and 2 male urethral samples) were cell culture negative and PCR test positive, while 1 pretreatment female endocervical sample was cell culture positive and PCR test negative. The posttreatment samples from all patients were cell culture negative, but the PCR test remained positive for 3 of 70 patients (1 female endocervical and 2 male urethral samples). One of these samples became spontaneously negative in three more weeks. The medical history of the individual patient and the negative PCR tests after treatment for nearly all patients support our hypothesis that the positive PCR test results were clinically relevant for the cell culture-negative but PCR test-positive but PCR test-positive patients of the population studied.

Comparison of nine antigen detection kits for diagnosis of urogenital infections due to Chlamydia psittaci in koalas

Chlamydia psittaci is the major cause of infectious disease in the koala (Phascolarctos cinereus). It causes four disease syndromes in the koala, namely, conjunctivitis, rhinitis, cystitis, and infertility (females only). Diagnosis of chlamydial infections in koalas relies primarily on isolation of the organism in cell culture. Serology has generally not been useful, and little use has previously been made of the commercially available antigen detection kits. We examined the sensitivity, specificity, and usefulness of three direct fluorescent-antibody kits (Vet-IF [Cell Labs], IMAGEN [Celltech], Chlamydia-Direct IF [Bio Merieux]) and six antigen detection enzyme-linked immunosorbent assay (ELISA) kits (Clearview [Unipath], Surecell [Kodak], Pathfinder [Kallestad], Chlamydia-EIA [Pharmacia], Chlamydiazyme [Abbott], IDEIA [Celltech]) for the detection of urogenital infections in koalas. Laboratory studies showed that the direct fluorescent-antibody kits were the least sensitive in this case and did not detect fewer than 10(4) elementary bodies per ml, while most ELISA kits detected between 130 and 600 elementary bodies per ml. Field study results showed that the Clearview kit was the most sensitive (91%) compared with the IDEIA (88%) and the Surecell (73%) kits. All three kits were more sensitive than cell culture (36%), highlighting viability loss problems that occur during transport. This study showed that the Clearview kit is sensitive, specific, and easy to use for the detection of type II (urogenital) C. psittaci from koalas in the field and warrants further evaluation.

Comparison of two culture approaches, blind passage and dual observation, for detecting Chlamydia trachomatis in various prevalence populations

Chlamydia trachomatis diagnosis in our laboratory consisted of dual inoculation of shell vials and detection of inclusions by using fluorescein-conjugated monoclonal antiserum; the second culture vial was conventionally used for blind passage when the first vial was negative. We compared the increase in positivity using blind passage with that of a strategy utilizing observation of two stained monolayers (dual observation) without blind passage, in an effort to reduce the reporting time and labor associated with the conventional approach. A total of 4,329 specimens were obtained from an obstetrics and gynecology (OB-GYN) clinic (2,563 specimens) and the sexually transmitted disease clinic (1,766 specimens). These specimens were used to compare the two strategies. Blind passage of 1,269 initially culture-negative specimens from the OB-GYN clinic resulted in an additional 6 positive chlamydial diagnoses. In comparison, a similar number of specimens (1,294) from the OB-GYN clinic collected subsequently to the first group were tested by dual observation. There were five additional positive findings. A similar evaluation of specimens from the sexually transmitted disease clinic was performed. Blind passage of 313 initially culture-negative specimens yielded 3 additional positive diagnoses, whereas dual observation of 1,435 similar specimens resulted in 9 positive diagnoses. On the basis of analysis of 4,332 specimens, sensitivity of dual observation is comparable to that of blind passage; labor, cost, and reporting time of dual observation are reduced in comparison to those of blind passage.

Recurrent genitourinary chlamydial infections in sexually active female adolescents

To determine the recurrence rate of chlamydial infections, we initially screened an urban population of 1308 sexually active female adolescents for chlamydial infection at the urethral and endocervical sites; these young women were followed and had additional examinations for infection. Chlamydial infection was documented by tissue culture in 31.1% (407) of them at some time during the study. After appropriate antibiotic treatment, 68.3% (278/407) returned for test-of-cure cultures within 3 months of their initial infection; of those 278, a total of 254 had sterile cultures. These patients were followed to determine the recurrence rate of chlamydial infections. Of these 254 patients, 177 (69.7%) had one or more follow-up visits; 38.4% (68/177) had a recurrent chlamydial infection. The majority of recurrent infections were documented within 9 months of the initial infection. Recurrent infections with the same serovar were frequent, suggesting reinfection by untreated partners or possible relapse of the initial chlamydial infection. This high rate of recurrent infection suggests that female adolescents should be rescreened frequently for genitourinary chlamydial infections.

Evaluation of two ELISA's for detecting Chlamydia trachomatis from endocervical swabs

Two enzyme immunoassays (EIAs) detecting Chlamydia trachomatis from endocervical swabs, Syva MicroTrak (MT) and Abbott Chlamydiazyme (CZ), were compared with a tissue culture (TC) standard. Initially, 8% (100 of 1250) of specimens were TC positive, yielding sensitivities of 94% (94 of 100) for MT and 79% (79 of 100) for CZ with identical 98% specificities (1129 of 1150 for MT and 1130 of 1150 for CZ). Discrepant specimens were retested by both EIAs and assayed for elementary bodies (EBs) by a fluorescent antibody test. After discrepancy analysis, 9.5% (118) of 1240 patients were either TC or EB positive, yielding sensitivities of 94.1% for MT (111 of 118) and 79.7% for CZ (94 of 118) with identical specificities of 100% (1122 of 1122). These results indicate that the MT is significantly more sensitive (p less than 0.05, McNemar test) than CZ in detecting C. trachomatis from endocervical swabs.

Accuracy of two enzyme immunoassays and cell culture in the detection of Chlamydia trachomatis in low and high risk populations in Senegal

Two enzyme immunoassays (EIAs), Chlamydiazyme (CZ; Abbott Laboratories) and Pathfinder (PF; Kallestadt), were compared with a cell culture technique in the detection of cervical Chlamydia trachomatis infection in 670 women in urban settings in Senegal (377 pregnant women and 293 prostitutes). Positive CZ and positive PF specimens were tested a second time using a monoclonal antibody blocking technique. True positive specimens were defined as those positive on culture or positive on EIA with confirmation of the result after blocking. Using this definition, the prevalence of genital chlamydial infection was 14.6% and 14.3% in pregnant women and prostitutes respectively. An important difference between the two populations was that the pregnant women were younger than the prostitutes, which might explain the fact that the prevalence of infection among the pregnant women was as high as that among the prostitutes, although the age-adjusted prevalence was higher among prostitutes than among pregnant women. The chlamydial detection rates of cell culture, CZ and PF were 62% (26/42), 69% (29/42) and 86% (36/42) respectively in prostitutes and 76% (42/55), 40% (22/55) and 53% (29/55) respectively in pregnant women. Agreement between the tests was 89%, 85% and 88% for culture/CZ, culture/PF and CZ/PF respectively. However, when data were adjusted for chance agreement, kappa coefficients were 0.40 for culture/CZ, 0.34 for culture/PF and 0.48 for CZ/PF. These results indicate that the accuracy of the EIAs and cell culture may vary greatly in different populations: both EIAs showed a distinctly higher detection rate than culture in prostitutes and a significantly lower detection rate in pregnant women.(ABSTRACT TRUNCATED AT 250 WORDS)

Estimating transmission probabilities for chlamydial infection

Estimates of transmission probabilities for sexually transmitted diseases historically come from studies of uninfected individuals exposed to those with a high disease prevalence (for example, prostitutes). However, changes in sexual behaviour, much of which relates to concerns about AIDS, has made identification of populations suitable for such studies extremely difficult. This paper presents a method for estimating these probabilities that utilizes a deterministic model and routinely collected data available in many clinics. Variance estimates for the estimators are also derived. Data for chlamydial infection and sensitivity analyses for the input parameters and assumptions illustrate the method.

Genital chlamydial infections: epidemiology and reproductive sequelae

Genital chlamydial infection is increasing and is now more common than gonorrhea. A sizable percentage of chlamydial infections of the lower genital tract in women progress to endometritis and salpingitis. Tubal infertility and ectopic pregnancy are important sequelae. Failure to control chlamydial infections reflects the following four factors: (1) Many cases are mild or asymptomatic; (2) diagnostic tests are expensive and technically demanding; (3) at least 7 days of multiple-dose therapy are currently required; and (4) partner notification is not routinely performed. Thus early identification of infected persons and compliance with curative therapy are less likely than with other sexually transmitted bacterial diseases.

Laboratory techniques for the diagnosis of chlamydial infections

Yolk-sac inoculation of embryonated eggs was superseded 25 years ago by the use of cell cultures (often McCoy) for the isolation of Chlamydia trachomatis. Centrifugation of specimens onto the cell monolayers was shown to increase sensitivity, but little of late has further improved sensitivity which is at least ten-fold greater than that of eggs. However, culture is slow and labour intensive so that non-cultural techniques without these drawbacks have come to dominate. Direct fluorescent antibody (DFA) tests are rapid and have sensitivities that range from 70% to 100% for men and 68% to 100% for women, and specificities that range from 87% to 99% for men and 82% to 100% for women; if the tests are read by competent observers the values are at the top end of the ranges. The detection rate may be enhanced even further by relatively low-speed centrifugation of specimens before staining. Skilled reading is not a feature of enzyme immunoassays (EIAs) which according to the literature have sensitivities that range from 62% to 97% for men and 64% to 100% for women, and specificities that range from 92% to 100% for men and 89% to 100% for women. However, comparison against poor reference tests is responsible for most of the higher values and the clinician should not be misled into believing that EIAs have excellent sensitivity; the lower values in the ranges are closer to reality. Furthermore, EIAs that are being designed for use by general practitioners should be regarded with the greatest caution since lack of sensitivity means that chlamydia-positive patients will go undetected. The polymerase chain reaction (PCR) is not bedevilled by insensitivity but it is no more sensitive than the most sensitive cell culture or DFA tests. PCR is unsuitable for routine diagnosis but has a place as a research tool. For men, examination of "first-catch" urine samples by the best of the non-cultural procedures provides an acceptable non-invasive approach to diagnosis; for women, the value of examining urine may be less, but needs to be thoroughly tested. However, there is little doubt that a Cytobrush used to obtain cervical specimens holds no practical advantage over a swab. Serological tests are reliant on the provision of paired sera for making a diagnosis; high antibody titres in single sera may be suggestive of an aetiological association in deep-seated chlamydial infections (epididymitis, arthritis, salpingitis, etc), but unequivocal interpretation is unusual, particularly in an individual case, since the distinction between a current and past infection is problematical.

Chlamydial infections

Chlamydia trachomatis is a unique intracellular parasite that causes a number of common sexually transmitted disease syndromes, including nongonococcal urethritis in both men and women, epididymitis in men, and pelvic inflammatory disease in women. Infants exposed at delivery are at risk for the development of conjunctivitis and pneumonia. There is strong evidence that Chlamydia is a cause of obstructive infertility and ectopic pregnancy in women. It appears that these complications result from the chronic inflammatory response and secondary scarring that are elicited by long-term asymptomatic or nearly asymptomatic fallopian tube infections. Because treatment with tetracycline, doxycycline, or erythromycin is simple, effective, and inexpensive, major efforts should be put into identifying asymptomatic young women through screening of the subpopulations at highest risk. These include sexually active adolescent women and older women who are not monogamous. Blacks are at higher risk than other ethnic groups for infection. The cost of diagnosing chlamydial infection has decreased with the introduction of new nonculture diagnostic tests. This should increase the availability of testing for screening purposes. It is critical to remember that male sex partners of infected women must be treated; otherwise all efforts to prevent long-term complications by identifying and treating asymptomatic women are doomed to failure.

Effect of patient characteristics on performance of an enzyme immunoassay for detecting cervical Chlamydia trachomatis infection

We compared the performance of a commercial enzyme immunoassay (EIA) (Chlamydiazyme; Abbott Diagnostics, North Chicago, Ill.) with that of cell culture for the detection of Chlamydia trachomatis cervical infection in 1,417 women attending public health clinics. Confirmatory chlamydial testing by a direct fluorescent-antibody test (MicroTrak; Syva Co., Palo Alto, Calif.) was performed on specimens from women who had positive EIAs. Overall, only 57% of women who had a positive chlamydial test by cell culture were also positive by EIA. We noted a strong association between the number of chlamydial inclusions in cell culture and a positive EIA outcome. The proportion of culture-positive women who also had a positive EIA declined with age and a history of previous sexually transmitted disease and increased among oral contraceptive users. The results of direct fluorescent-antibody confirmatory testing suggested that cell culture was also insensitive for the detection of C. trachomatis infection. Our observations demonstrate that the performance of the chlamydial EIA may vary greatly with individual patient characteristics and that the utility of EIA as a screening test may be limited, especially in older women.

Quantitative culture of endocervical Chlamydia trachomatis

We examined the number of Chlamydia trachomatis inclusions produced in the initial passage of cell cultures of endocervical specimens from 1,231 women with positive chlamydial cultures who attended a sexually transmitted diseases clinic. Youth, white race, oral contraceptive use, and concurrent infection by Neisseria gonorrhoeae were associated with high chlamydial inclusion counts. Youth, white race, and oral contraceptive use were independent determinants of a high chlamydial inclusion count in women without concurrent gonorrhea but not in women with gonorrhea. Results of our study suggest that the degree of chlamydial excretion from the infected cervix may be influenced by characteristics of the patient being tested and may affect the ability to detect C. trachomatis in different patient groups.

Comparison of a DNA probe with culture for detecting Chlamydia trachomatis directly from genital specimens

A study was conducted to compare results between culture methods and the Gen-Probe (Gen-Probe Inc. San Diego, California) chemiluminescent technique of nucleic acid hybridization to identify Chlamydia trachomatis from genital specimens from 117 females and 70 males. Specimens collected from sexually transmitted diseases (STD) and infertility clinics were randomized as to whether probe or culture swabs were collected first. The Gen-Probe demonstrated a sensitivity of 83% and a specificity of 75% in the female population and a sensitivity of 68% and a specificity of 75% in the male population when compared to the reference culture method using cycloheximide-treated McCoy cells. Gen-Probe had an overall sensitivity of 74% and specificity of 75% when the two groups were combined. Chlamydiazyme (Abbott Labs) results were obtained on 135 specimens; 90 of which correlated with probe and culture. The remaining 45 specimens had varying combinations of probe, culture and Chlamydiazyme results. MicroTrak (Syva) was done on 49 specimens; 35 of which correlated with probe and culture. The remaining 14 specimens had varying combinations of probe, culture and MicroTrak results. The apparent lack of sensitivity of the DNA probe is a major drawback of this system.

Comparison of buffalo green monkey cells and McCoy cells for isolation of Chlamydia trachomatis in a microtiter system

A total of 1,229 urogenital samples of patients with sexually transmitted diseases and prostitutes were inoculated simultaneously in McCoy cells and Buffalo green monkey (BGM) cells by using a microtitration technique. BGM cells proved to be slightly more sensitive than McCoy cells, and they usually showed more and larger inclusions and were more resistant to cytotoxic substances in samples. The decrease in sensitivity as a result of mycoplasmal contamination was much more prominent in McCoy cells than in BGM cells.

Recovery of Chlamydia trachomatis from endometrial and fallopian tube biopsies in women with infertility of tubal origin

In order to examine the role of chronic active chlamydial infection in tubal infertility, cultures for Chlamydia trachomatis were performed on endometrial biopsies from 38, and fallopian tube biopsies from all, of 52 women undergoing tubal surgery for infertility. C. trachomatis was recovered from one or both sites in 8 of 52 (15%). Five of 6 women with positive fallopian tube cultures had endometrial cultures performed, and of these, 4 (80%) were positive. Three culture-positive women had been treated with tetracycline or doxycycline. Multiple blind passage in tissue culture was required for recovery of all six fallopian tube and four of the six endometrial isolates. No specific anatomic lesion was associated with documented infection. Chronic active chlamydial infection is frequently associated with tubal infertility, may persist despite therapy, and often can be detected by endometrial biopsy culture.

Detecting Chlamydia trachomatis in men with urethritis: serology v isolation in cell culture

The accuracy of single serovar (L2) inclusion immunoperoxidase assay (IPA) to show serum IgG and IgA antibodies specific to chlamydiae was compared with culture for Chlamydia trachomatis to diagnose chlamydial infection in 73 men with acute urethritis. C trachomatis only was isolated from 18 (25%), Neisseria gonorrhoeae only from 17 (23%), and both organisms from six (8%). Thus 24 (33%) yielded chlamydiae. Assays based on IgG antibodies to chlamydiae at a titre of 1/64 or more showed high sensitivity (96%) and a good negative predictive value (80%), but low specificity (13%) and agreement (48%) compared with culture. IgG antibodies to chlamydiae at a titre of 1/128 or more showed lower sensitivity (75%) but higher specificity (72%), negative predictive value (79%), and agreement (73%). IgA antibodies to chlamydiae at a titre of 1/8 or more showed a sensitivity of 88%, specificity of 72%, negative predictive value of 88%, and agreement of 79%. An appreciable (fourfold or more) decrease in IgA and IgG titres was observed in most (10) of the 15 men from whom second blood samples were obtained one to two years after treatment. Measuring specific IgA and IgG antibodies to chlamydiae by IPA may serve as a useful complementary test for diagnosing and following up patients with urethritis.

Effect of differences in specimen processing and passage technique on recovery of Chlamydia trachomatis

We have previously found that optimum recovery of Chlamydia trachomatis in microdilution plate culture required multiple blind passages. However, others have found this not to be the case for culture in vials. In the present study, the effect on recovery of the use of vials (as opposed to microdilution plates) and the effect of vortexing, sonication, or both were compared. Three different passage techniques were also evaluated. Vortexing or sonication resulted in equivalent recoveries. However, compared with vortexing alone, a combination of vortexing and sonication increased recovery from 95 (78%) to 114 (94%) of 121 positive specimens (P = 0.002). In multiple-passage experiments, the combination of vortexing and sonication, compared with vortexing only, increased the proportion of isolates recovered with no more than a single passage from 81 to 96%. Substitution of vials for microdilution plates increased recovery with only a single passage to greater than 96%, irrespective of whether sonication was employed. The most sensitive technique for single-passage technique was one using blunt scraping of cell monolayers with passage of two monolayers to one. The sensitivity of cell culture for C. trachomatis is highly dependent on the technique(s) employed. However, the combination of sonication and vortexing of clinical specimens enhanced recovery in microdilution plates, and a single blind passage did so in both microdilution plates and vials. Consideration should be given to their use for routine clinical cultures.

Chlamydia trachomatis cervical infection in women seeking routine gynecologic care: criteria for selective testing

PURPOSE

Chlamydia trachomatis infection is one of the most common sexually transmitted diseases. Developing methods to identify patients who are at higher risk would enable clinicians to perform selective testing for C. trachomatis infection, which may reduce morbidity, sequelae, and overall costs. Risk factors for C. trachomatis infection of the cervix in women seen for routine gynecologic care were therefore analyzed.

PATIENTS AND METHODS

Extensive clinical data and cervical cultures were obtained from 1,141 women between the ages of 18 and 50. Multivariate techniques were used to develop and prospectively test a model to predict infection.

RESULTS

In the model development series of 530 patients seen in a hospital-based practice, 24 (4.5%) had a positive culture result. In the validation series of 611 patients seen in private practice, 17 (2.8%) had positive culture results. The majority of infected patients (61%) were asymptomatic. For sexually active women 18 to 35 years of age, the optimal predictive model was based on three factors: level of education (high school or less), a sex partner with other partners during the prior three months, and endocervical bleeding induced by the initial swab. In the validation series, the prevalence of infection for women with one or more of these factors was 5.8% (95% confidence interval, 4.0 to 8.6) compared with 0.9% in patients without these factors (p = 0.005).

CONCLUSION

Clinical information can be used in a low-prevalence population to predict a patient's risk for C. trachomatis infection and to select patients for testing.

Laboratory diagnosis of human chlamydial infections

Chlamydia trachomatis is a human pathogen that causes ocular disease (trachoma and inclusion conjunctivitis), genital disease (cervicitis, urethritis, salpingitis, and lymphogranuloma venereum), and respiratory disease (infant pneumonitis). Respiratory chlamydioses also occur with infection by avian strains of C. psittaci or infection by the newly described TWAR agent. Diagnosis of most acute C. trachomatis infections relies on detection of the infecting agent by cell culture, fluorescent antibody, immunoassay, cytopathologic, or nucleic acid hybridization methods. Individual non-culture tests for C. trachomatis are less sensitive and specific than the best chlamydial cell culture system but offer the advantages of reduced technology and simple transport of clinical specimens. Currently available nonculture tests for C. trachomatis perform adequately as screening tests in populations in which the prevalence of infection is greater than 10%. A negative culture or nonculture test for C. trachomatis does not, however, exclude infection. The predictive value of a positive nonculture test may be unsatisfactory when populations of low infection prevalence are tested. Tests that detect antibody responses to chlamydial infection have limited utility in diagnosis of acute chlamydial infection because of the high prevalence of persistent antibody in healthy adults and the cross-reactivity due to infection by the highly prevalent C. trachomatis and TWAR agents. Assays for changes in antibody titer to the chlamydial genus antigen are used for the diagnosis of respiratory chlamydioses. A single serum sample that is negative for chlamydial antibody excludes the diagnosis of lymphogranuloma venereum.

Historical and clinical factors associated with Chlamydia trachomatis genitourinary infection in female adolescents

Five hundred sixty-eight adolescent female patients receiving routine gynecologic care at urban clinics were screened by culture for Chlamydia trachomatis infection at both the urethra and endocervix. Culture results for 562 were available from either or both sites. Positive cultures were obtained from 139 (25%). Urethral infection was not associated with either urinary tract symptoms or sterile pyuria, but urethral or endocervical infection was associated with cervical friability (P = less than 0.0001), endocervical mucopus (P = 0.0001), cervical erythema (P = 0.0002), and cervical ectopy or erosion (P = 0.01). Increased chlamydial infection rates were associated with older age (P = 0.01), history of more frequent intercourse (P = 0.01), and history of more than one lifetime partner (P = 0.023), with a marginal association for being black (P = 0.05). Method of contraception, reason for attending clinic, age at menarche, age at first intercourse, years sexually active, number of sexual partners in preceding 6 months, parity, and prior history of sexually transmitted disease were not associated with having chlamydial genitourinary infection.

Tubal factor infertility: an association with prior chlamydial infection and asymptomatic salpingitis

In 265 Canadian women, with and without tubal factor infertility (TFI), we compared Chlamydia trachomatis cultures of endocervical swabs, endotubal swabs and biopsies, serology, and past history. A history of pelvic inflammatory disease (PID) was absent in 69.2% of TFI women, despite visual evidence of tubal damage. C. trachomatis was not isolated in any of 52 patients with TFI (TFI group), 114 having tubal ligation (STER group), or 99 patients having hysterectomy (HYST group). However, chlamydial antigen was detected with an immunochemical method in 1 of 16 tubal biopsy specimens from TFI women. The prevalence of chlamydial IgM or IgG antibody in serum was significantly higher (P less than 0.0001) in the TFI group (79.1%) than in the other two groups (relative odds, 6.3; 95% confidence interval: 2.5, 16.8). In seropositive (IgG or IgM) subjects, there was a significant (P = 0.003) and strong (relative odds, 5.1; 95% confidence interval: 1.5, 18.1) association between chlamydial IgA antibody and TFI. In women with TFI, there was no significant association between IgM or IgG seropositivity (P = 0.56). or IgA seropositivity (P = 0.53), and a negative history for PID. These findings are consistent with the hypothesis that C. trachomatis is a major cause of TFI following PID, which may or may not be asymptomatic.

Testing for Chlamydia trachomatis

Chlamydia trachomatis is a highly prevalent and damaging sexually transmitted disease. Since it may occur in an asymptomatic state, it is important for family physicians to know when screening or testing for this infection is indicated. The value of screening may be increased by correct collection, storage and transport of specimens. The techniques currently used in the laboratory to test specimens for chlamydia include cell culture, ELISA and immunofluorescent antibody (IFA) assay. Cell culture remains the 'gold standard'. The IFA and ELISA are simpler and quicker to perform than is culture and have sufficiently comparable measurements of accuracy.