Design of the FemCure study: prospective multicentre study on the transmission of genital and extra-genital Chlamydia trachomatis infections in women receiving routine care

Nanoparticle-Based Lateral Flow Biosensor Integrated With Loop-Mediated Isothermal Amplification for Rapid and Visual Identification of Chlamydia trachomatis for Point-of-Care Use

Chlamydial infection, caused by Chlamydia trachomatis, is the most common bacterial sexually transmitted infection and remains a major public health problem worldwide, particularly in underdeveloped regions. Developing a rapid and sensitive point-of-care (POC) testing for accurate screening of C. trachomatis infection is critical for earlier treatment to prevent transmission. In this study, a novel diagnostic assay, loop-mediated isothermal amplification integrated with gold nanoparticle-based lateral flow biosensor (LAMP-LFB), was devised and applied for diagnosis of C. trachomatis in clinical samples. A set of LAMP primers based on the ompA gene from 14 C. trachomatis serological variants (serovar A-K, L1, L2, L3) was successfully designed and used for the development of C. trachomatis-LAMP-LFB assay. The optimal reaction system can be performed at a constant temperature of 67°C for 35 min. The total assay process, including genomic DNA extraction (~15 min), LAMP reaction (35 min), and LFB readout (~2 min), could be finished within 60 min. The C. trachomatis-LAMP-LFB could detect down to 50 copies/ml, and the specificity was 100%, no cross-reactions with other pathogens were observed. Hence, our C. trachomatis-LAMP-LFB was a rapid, reliable, sensitive, cost-effective, and easy-to-operate assay, which could offer an attractive POC testing tool for chlamydial infection screening, especially in resource starvation settings.

Incident urogenital and anorectal Chlamydia trachomatis in women: the role of sexual exposure and autoinoculation: a multicentre observational study (FemCure)

BACKGROUND

Anorectal infections with Chlamydia trachomatis (CT) are common in women visiting STI outpatient clinics. We here evaluated the risk posed by sexual exposure and by alternate anatomical site infection for incident anorectal and urogenital CT.

METHODS

Prospective multicentre cohort study, FemCure. Participants were treated for CT, and after 4, 6, 8, 10 and 12 weeks, they self-collected anorectal and urogenital samples (swabs) for CT-DNA testing. We calculated the proportion with incident CT, that is, CT incidence (at weeks 6-12) by 2-week time-periods. Compared with no exposure (A), we estimated the risk of incident CT for (B) sexual exposure, (C) alternate site anatomic site infection and (D) both, adjusted for confounders and expressed as adjusted ORs with 95% CIs.

RESULTS

We analysed data of 385 participants contributing 1540 2-week periods. The anorectal CT incidence was 2.9% (39/1343) (95 CI 1.8 to 3.6); 1.3% (A), 1.3% (B), 27.8% (C) and 36.7% (D). The ORs were: 0.91 (95% CI 0.32 to 2.60) (B), 26.0 (95% CI 7.16 to 94.34) (C), 44.26 (95% CI 14.38 to 136.21) (D).The urogenital CT incidence was 3.3% (47/1428) (95% CI 2.4 to 4.4); 0.7% (A), 1.9% (B), 13.9% (C) and 25.4% (D). The ORs were: 2.73 (95% CI 0.87 to 8.61) (B), 21.77 (95% CI 6.70 to 70 71) (C) and 49.66 (95% CI 15.37 to 160.41) (D).

CONCLUSIONS

After initial treatment, an alternate anatomical site CT infection increased the risk for an incident CT in women, especially when also sex was reported. This may suggest a key role for autoinoculation in the re-establishment or persistence of urogenital and anorectal chlamydia infections.

Determinants associated with viable genital or rectal Chlamydia trachomatis bacterial load (FemCure)

BACKGROUND

Chlamydia trachomatis (CT) is routinely diagnosed by nucleic acid amplification tests (NAATs), which are unable to distinguish between nucleic acids from viable and non-viable CT organisms.

OBJECTIVES

We applied our recently developed sensitive PCR (viability PCR) technique to measure viable bacterial CT load and explore associated determinants in 524 women attending Dutch sexual health centres (STI clinics), and who had genital or rectal CT.

METHODS

We included women participating in the FemCure study (Netherlands, 2016-2017). At the enrolment visit (pre-treatment), 524 were NAAT positive (n=411 had genital and rectal CT, n=88 had genital CT only and n=25 had rectal CT only). We assessed viable rectal and viable genital load using V-PCR. We presented mean load (range 0 (non-viable) to 6.5 log₁₀ CT/mL) and explored potential associations with urogenital symptoms (coital lower abdominal pain, coital blood loss, intermenstrual bleeding, altered vaginal discharge, painful or frequent micturition), rectal symptoms (discharge, pain, blood loss), other anatomical site infection and sociodemographics using multivariable regression analyses.

RESULTS

In genital (n=499) CT NAAT-positive women, the mean viable load was 3.5 log₁₀ CT/mL (SD 1.6). Genital viable load was independently associated with urogenital symptoms-especially altered vaginal discharge (Beta=0.35, p=0.012) and with concurrent rectal CT (aBeta=1.79; p<0.001). Urogenital symptoms were reported by 50.3% of women; their mean genital viable load was 3.6 log₁₀ CT/mL (vs 3.3 in women without symptoms). Of 436 rectal CT NAAT-positive women, the mean rectal viable load was 2.2 log₁₀ CT/mL (SD 2.0); rectal symptoms were reported by 2.5% (n=11) and not associated with rectal viable load.

CONCLUSION

Among women diagnosed with CT in an outpatient clinical setting, viable genital CT load was higher in those reporting urogenital symptoms, but the difference was small. Viable genital load was substantially higher when women also had a concurrent rectal CT.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov NCT02694497.

Treatment Effectiveness of Azithromycin and Doxycycline in Uncomplicated Rectal and Vaginal Chlamydia trachomatis Infections in Women: A Multicenter Observational Study (FemCure)

Background

Rectal infections with Chlamydia trachomatis (CT) are prevalent in women visiting a sexually transmitted infection outpatient clinic, but it remains unclear what the most effective treatment is. We assessed the effectiveness of doxycycline and azithromycin for the treatment of rectal and vaginal chlamydia in women.

Methods

This study is part of a prospective multicenter cohort study (FemCure). Treatment consisted of doxycycline (100 mg twice daily for 7 days) in rectal CT–positive women, and of azithromycin (1 g single dose) in vaginally positive women who were rectally untested or rectally negative. Participants self-collected rectal and vaginal samples at enrollment (treatment time-point) and during 4 weeks of follow-up. The endpoint was microbiological cure by a negative nucleic acid amplification test at 4 weeks. Differences between cure proportions and 95% confidence intervals (CIs) were calculated.

Results

We analyzed 416 patients, of whom 319 had both rectal and vaginal chlamydia at enrollment, 22 had rectal chlamydia only, and 75 had vaginal chlamydia only. In 341 rectal infections, microbiological cure in azithromycin-treated women was 78.5% (95% CI, 72.6%–83.7%; n = 164/209) and 95.5% (95% CI, 91.0%–98.2%; n = 126/132) in doxycycline-treated women (difference, 17.0% [95% CI, 9.6%–24.7%]; P < .001). In 394 vaginal infections, cure was 93.5% (95% CI, 90.1%–96.1%; n = 246/263) in azithromycin-treated women and 95.4% (95% CI, 90.9%–98.2%; n = 125/131) in doxycycline-treated women (difference, 1.9% [95% CI, –3.6% to 6.7%]; P = .504).

Conclusions

The effectiveness of doxycycline is high and exceeds that of azithromycin for the treatment of rectal CT infections in women.

Clinical Trials Registration

NCT02694497.

Oropharyngeal Chlamydia trachomatis in women; spontaneous clearance and cure after treatment (FemCure)

OBJECTIVES

Women attending STI clinics are not routinely tested for oropharyngeal Chlamydia trachomatis (CT) infections. We aimed to assess spontaneous clearance of oropharyngeal CT and cure after antibiotic treatment in women.

METHODS

Women with vaginal or rectal CT (n=560) were recruited at STI clinics in 2016-2017, as part of the FemCure study (prospective cohort study). We included participants' data from week -1, that is, the diagnosis at initial visit, when clinics applied selective oropharyngeal testing. At week -1, a total of 241 women were oropharyngeally tested (30 positive) and 319 were untested. All FemCure participants provided nurse-collected oropharyngeal samples at study enrolment, that is, week 0, just prior to treatment (n=560), and after treatment at weeks 4 (n=449), 8 (n=433) and 12 (n=427). Samples were tested by nucleic acid amplification test, and at week 0 also by viability testing by viability PCR. Proportions of oropharyngeal CT test results were presented to represent spontaneous clearance and cure.

RESULTS

Of 30 women diagnosed with oropharyngeal CT at week -1, fifteen (50%) were negative at week 0 after a median of 9 days, that is, 'spontaneous clearance'. At week 0, a total of 560 participants were tested, and 46 (8.8%) were oropharyngeal CT positive; 12 of them (26.1%) had viable CT. Of the 46 positive, 36 women had an oropharyngeal test after treatment; 97.2% (35/36) were negative at week 4, that is, 'cure'. Of all women with follow-up visits, the proportion of oropharyngeal CT positive was between 0.5% and 1.6% between weeks 4 and 12. Of those not tested at week -1 (n=319), 8.5% (n=27) were oropharyngeal positive at week 0.

CONCLUSIONS

The clinical importance of oropharyngeal CT in women is debated. We demonstrated that spontaneous clearance of oropharyngeal CT among women is common; of those who did not clear for CT, three-quarters had non-viable CT. After regular treatment with azithromycin or doxycycline, cure rate (97%) of oropharyngeal CT is excellent.

TRIAL REGISTRATION NUMBER

NCT02694497.

Participation, retention, and associated factors of women in a prospective multicenter study on Chlamydia trachomatis infections (FemCure)

Prospective studies are key study designs when attempting to unravel health mechanisms that are widely applicable. Understanding the internal validity of a prospective study is essential to judge a study's quality. Moreover, insights in possible sampling bias and the external validity of a prospective study are useful to judge the applicability of a study's findings. We evaluated participation, retention, and associated factors of women in a multicenter prospective cohort (FemCure) to understand the study's validity.Chlamydia trachomatis (CT) infected adult women, negative for HIV, syphilis, and Neisseria gonorrhoeae were eligible to be preselected and included at three sexually transmitted infection (STI) clinics in the Netherlands (2016-2017). The planned follow-up for participants was 3 months, with two weekly rectal and vaginal CT self-sampling and online questionnaires administered at home and at the clinic. We calculated the proportions of preselected, included, and retained (completed follow-up) women. Associations with non-preselection, noninclusion, and non-retention (called attrition) were assessed (logistic and Cox regression).Among the 4,916 women, 1,763 (35.9%) were preselected, of whom 560 (31.8%) were included. The study population had diverse baseline characteristics: study site, migration background, high education, and no STI history were associated with non-preselection and noninclusion. Retention was 76.3% (n = 427). Attrition was 10.71/100 person/month (95% confidence interval 9.97, 12.69) and was associated with young age and low education. In an outpatient clinical setting, it proved feasible to include and retain women in an intensive prospective cohort. External validity was limited as the study population was not representative (sampling bias), but this did not affect the internal validity. Selective attrition, however (potential selection bias), should be accounted for when interpreting the study results.

Spontaneous clearance of Chlamydia trachomatis accounting for bacterial viability in vaginally or rectally infected women (FemCure)

OBJECTIVES

Spontaneous clearance of Chlamydia trachomatis (CT) infections can occur between diagnosis and treatment. We followed CT patients to assess clearance using a conventional definition (no total CT-DNA, assessed by routine quantitative PCR methods) and a definition accounting for viability, assessed by viability PCR testing.

METHODS

Three outpatient STI clinics included CT-diagnosed women (The Netherlands, 2016-2017, FemCure study); participants had vaginal CT (vCT) and rectal CT (rCT) (group A: n=155), vCT and were rectally untested (group B: n=351), single vCT (group C: n=25) or single rCT (group D: n=29). Follow-up (median interval 9 days) vaginal and rectal samples underwent quantitative PCR testing (detecting total CT-DNA). When PCR positive, samples underwent V-PCR testing to detect 'viable CT' (CT-DNA from intact CT organisms; V-PCR positive). 'Clearance' was the proportion PCR-negative patients and 'clearance of viable CT' was the proportion of patients testing PCR negative or PCR positive but V-PCR negative. We used multivariable logistic regression analyses to assess diagnosis group (A-D), age, days since initial CT test (diagnosis) and study site (STI clinic) in relation to clearance and clearance of viable CT.

RESULTS

Clearance and clearance of viable CT at both anatomic sites were for (A) 0.6% and 3.9%; (B) 5.4% and 9.4%; (C) 32.0% and 52.0% and (D) 27.6% and 41.4%, respectively. In multivariate analyses, women with single infections (groups C and D) had higher likelihood of clearance than women concurrently infected with vCT and rCT (p<0.001).Of rectally untested women (group B), 76.9% had total CT-DNA and 46.7% had viable CT (V-PCR positive) at the rectal site.

CONCLUSIONS

Of untreated female vCT patients who had CT also at the rectal site, or who were rectally untested, only a small proportion cleared CT (in fact many had viable CT) at their follow-up visit (median 9 days). Among single site infected women clearance was much higher.

TRIAL REGISTRATION NUMBER

NCT02694497.

Assessment of rectal Chlamydia trachomatis viable load in women by viability-PCR

OBJECTIVES

In recent years, studies have demonstrated frequent rectal Chlamydia trachomatis (CT) detection in women, irrespective of reported anal sex or rectal symptoms. However, the clinical relevance and public health implication of rectal CT detection in women remain under debate. Therefore, evaluating CT viability may provide more insight into the relevance of standard routine nucleic acid amplification test (NAAT)-positive results.

METHODS

In this cross-sectional explorative study, a convenience sample of female patients at our STI clinic aged 18 years or older, diagnosed with vaginal and/or rectal CT, were invited to participate. On return for treatment, rectal CT-diagnosed women were instructed to self-collect rectal swab samples before being treated. Standard COBAS 4800 CT/NG routine NAAT testing was applied for CT diagnosis. Rectal viable CT load was evaluated by using viability-PCR (V-PCR).

RESULTS

53 women with rectal CT were included in this study; 86.8% (46/53) had a quantifiable rectal total CT load. Of women with quantifiable samples, 52.2% (24/46) had viable CT detected from rectal swabs by V-PCR, with a mean rectal viable CT load of 3.31 log₁₀ CT/mL (range 1.16-6.22). No statistically significant difference (p=0.73) was observed in the mean rectal viable CT load of women with an indication for rectal testing (n=9) and without (n=15), 3.20 log₁₀ CT/mL (range 2.06-4.36) and 3.38 log₁₀ CT/mL (range 1.16-6.22), respectively. CT culture yielded positive test results from rectal swabs in 22.6% (12/53) of rectal CT NAAT-diagnosed women. Of women with viable rectal CT by V-PCR (n=24), 50% (12/24) were positive by CT culture.

CONCLUSIONS

Overall, the detection of high rectal viable CT loads in this study indicates that rectal CT in some women might represent a currently ongoing infection rather than just the presence of remnant DNA from dead bacteria or only contamination from an active vaginal CT infection.

Genital and anal Chlamydia trachomatis bacterial load in concurrently infected women: a cross-sectional study

OBJECTIVES

Most international STI guidelines recommend Chlamydia trachomatis anorectal testing in women after self-reported sexual exposure or symptoms in women. However, it has been shown that the prevalence of anorectal C. trachomatis is as high (7%-17 %) in women who do not report anorectal intercourse (AI) as in women who do. This study assessed the correlation between the genital and anorectal C. trachomatis load in concurrently infected women for increased microbiological insight.

METHODS

A convenience sample of 105 women with a concurrent (genital and anorectal) C. trachomatis infection was included from the STI clinic in South Limburg, the Netherlands. Women provided self-collected vaginal and anorectal swabs. The C. trachomatis load was quantified with qPCR and the human cell load was assessed to ensure sample adequacy. Genital and anorectal C. trachomatis loads were divided into tertiles for comparison. The χ² test and linear regression were used to compare genital and anorectal C. trachomatis loads and identify determinants associated with load.

RESULTS

The overall median C. trachomatis load was higher in genital (median 5.3 log₁₀ C. trachomatis/ml) than anorectal samples (median 3.4, p ≤ 0.001), but both loads were within the same range. The genital and anal load categories were not related within one woman (p = 0.99), both in women with and without AI. The anorectal C. trachomatis load was in the same or higher load category than the genital load in 56% of women without AI, and 79% of women with AI.

CONCLUSIONS

Although no cut-off for clinical relevance is known, an anorectal C. trachomatis load in the same or higher load category than the genital C. trachomatis load is likely to be clinically relevant. Other measurements should also be taken into account, such as leucocytes or bacterial viability to distinguish infection from contamination or exposure.

Review of Chlamydia trachomatis viability methods: assessing the clinical diagnostic impact of NAAT positive results

INTRODUCTION

Chlamydia trachomatis (chlamydia) is the most commonly diagnosed bacterial sexually transmitted infection (STI) worldwide. The advancement of molecular techniques has made chlamydia diagnostics infinitely easier. However, molecular techniques lack the information on chlamydia viability. Where in routine diagnostics the detection of chlamydia DNA or RNA might suffice, in other patient scenarios, information on the viability of chlamydia might be essential. Areas covered: In this review, the authors discuss the specific strengths and limitations of currently available methods to evaluate chlamydia viability: conventional cell culture, messenger RNA (mRNA) detection and viability-PCR (V-PCR). PubMed and Google Scholar were searched with the following terms: Chlamydia trachomatis, Treatment failure, Anal chlamydia, Microbial viability, Culture, Viability-PCR, Messenger RNA, and Molecular diagnostics Expert commentary: Several techniques are currently available to determine chlamydia viability and thus the clinical relevance of a positive test result in clinical samples. Depending on the underlying research question, all three discussed techniques have their merits when testing for viability. However, mRNA methods show the most promise in determining the presence of a true infection, in case the chlamydia reticulate body can be specifically detected. Further research is needed to understand how to best apply viability testing in current chlamydia diagnostics.

High Proportion of Anorectal Chlamydia trachomatis and Neisseria gonorrhoeae After Routine Universal Urogenital and Anorectal Screening in Women Visiting the Sexually Transmitted Infection Clinic

Background.

Testing on indication of self-reported anal sex or symptoms is used to manage anorectal Chlamydia trachomatis (chlamydia) and Neisseria gonorrhoeae (gonorrhea) infections in women. Little is known about the impact of another testing strategy, routine universal anorectal screening with respect to chlamydia and gonorrhea prevalence and risk factors.

Methods.

All women (n = 1012) aged ≥16 years attending our sexually transmitted infection clinic in 2015 were offered routine universal screening. In total, 19.5% (n = 185) of women had an indication (reported anal sex or symptoms), 72.5% (n = 689) did not have an indication, and 8.0% (n = 76) had missing information on indication. Logistic regression analyses were used to identify determinants associated with anorectal chlamydia and gonorrhea.

Results.

Of all women who visited our clinic, 94% (n = 950) participated in the study. Overall anorectal chlamydia/gonorrhea positivity was 13.4% (n = 127)/1.3% (n = 12). Self-reported anal sex and anal symptoms were independently associated with anorectal gonorrhea (odds ratios [ORs], 3.3 [95% confidence interval {CI}, 1.01-10.7] and 14.5 [95% CI, 2.8-75.0], respectively), but not with anorectal chlamydia. Of all anorectal chlamydia/gonorrhea cases, 72% (n = 92)/33% (n = 4) were diagnosed in women without an indication, of which 19% (n = 19)/0% (n = 0) were anorectal only. For women with missing indication, this was 7% (n = 9)/8% (n = 1) and 44% (n = 4)/100% (n = 1).

Conclusions.

Anorectal screening in women without an indication is feasible and highly acceptable. Selective testing on indication could be an appropriate control strategy for anorectal gonorrhea, as few infections would be missed. In contrast, selective testing is a suboptimal control strategy for anorectal chlamydia, as we found a high prevalence in women both with and without indication for anorectal testing, along with a substantial amount of anorectal-only infections.

Viability-PCR Shows That NAAT Detects a High Proportion of DNA from Non-Viable Chlamydia trachomatis

Objectives

According to the current guidelines for laboratory diagnosis of sexually transmitted infections (STIs), nucleic acid amplification tests (NAATs) are the preferred diagnostic method for Chlamydia trachomatis (CT) infections. However, NAATs amplify the available target DNA without discriminating between DNA originating from viable or non-viable CT. Assessing CT viability will provide more insights in the clinical and public health relevance of a CT positive test result. The aim of this study was to technically validate and implement viability-PCR (V-PCR) to asses CT viability.

Methods

Technical validation of V-PCR was performed by the assessment of predefined viability ratios of CT. Samples were subjected to V-PCR which consisted of propidium monoazide (PMA) treatment prior to DNA extraction followed by quantitative PCR (qPCR) targeting the ompA gene for the detection of CT DNA. Finally, V-PCR was applied to vaginal swabs of 50 CT positive patients, as indicated by routine NAAT, collected at our outpatient STD clinics before antimicrobial treatment.

Results

Technical validation of V-PCR showed that PMA treatment of heat-inactivated CT culture resulted in an almost complete loss of qPCR signal. PMA treated samples of the fresh viable CT culture showed no marked reduction of PCR signal, indicating that all DNA from viable CT could be detected. Applying V-PCR to clinical samples showed that in 36% of samples (18/50) less than 1% of CT DNA originated from viable bacteria.

Conclusions

V-PCR showed to be a fast and easy method to assess CT viability in clinical samples, without the need of traditional challenging cell culture methods. Furthermore, V-PCR results of clinical samples have indicated that a substantial amount of the amplified CT DNA originated from non-viable cells. Although results might be influenced by cell death during transport, this study suggests that there is a potential overestimation of quantitative CT positivity by currently used NAATs.