Review of use of a new rapid real-time PCR, the Cepheid GeneXpert® (Xpert) CT/NG assay, for Chlamydia trachomatis and Neisseria gonorrhoeae: results for patients while in a clinical setting

Economic evaluation alongside a clinical trial of near-to-patient testing for sexually transmitted infections

BACKGROUND

Current clinical care for common bacterial STIs (Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG) and Mycoplasma genitalium (MG)) involves empiric antimicrobial therapy when clients are symptomatic, or if asymptomatic, waiting for laboratory testing and recall if indicated. Near-to-patient testing (NPT) can improve pathogen-specific prescribing and reduce unnecessary or inappropriate antibiotic use in treating sexually transmitted infections (STI) by providing same-day delivery of results and treatment.

METHODS

We compared the economic cost of NPT to current clinic practice for managing clients with suspected proctitis, non-gonococcal urethritis (NGU), or as an STI contact, from a health provider's perspective. With a microsimulation of 1000 clients, we calculated the cost per client tested and per STI- and pathogen- detected for each testing strategy. Sensitivity analyses were conducted to assess the robustness of the main outcomes. Costs are reported as Australian dollars (2023).

RESULTS

In the standard care arm, cost per client tested for proctitis, NGU in men who have sex with men (MSM) and heterosexual men were the highest at $247.96 (95% Prediction Interval (PI): 246.77-249.15), $204.23 (95% PI: 202.70-205.75) and $195.01 (95% PI: 193.81-196.21) respectively. Comparatively, in the NPT arm, it costs $162.36 (95% PI: 161.43-163.28), $158.39 (95% PI: 157.62-159.15) and $149.17 (95% PI: 148.62-149.73), respectively. Using NPT resulted in cost savings of 34.52%, 22.45% and 23.51%, respectively. Among all the testing strategies, substantial difference in cost per client tested between the standard care arm and the NPT arm was observed for contacts of CT or NG, varying from 27.37% to 35.28%.

CONCLUSION

We found that NPT is cost-saving compared with standard clinical care for individuals with STI symptoms and sexual contacts of CT, NG, and MG.

Clinic-based evaluation of the dual Xpert CT/NG assay on the GeneXpert System for screening for extragenital chlamydial and gonococcal infections amongst men who have sex with men

BACKGROUND

Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) infections have increased globally. Asymptomatic infections represent a significant risk of long-term complications. Men who have sex with men (MSM) are disproportionally affected, underscoring the need to offer screening programmes to this population. CT/NG Point of Care Testing (POCT) constitutes a strategic tool to improve the continuum of STI care, however extensive real-life evaluations amongst at risk populations are lacking. The aim of this study is to estimate the GeneXpert CT/NG assay performance and usability for CT and NG at genital and extragenital sites for screening amongst MSM.

METHODS

This study was a multi-site sexual health clinic-based evaluation (Italy, Malta and Peru) with consecutive enrolment. A first void urine sample (divided in two aliquots), two oropharyngeal and two anorectal swabs were collected for each study participant. One specimen set (one for each anatomical site) was tested with the dual index test (Cepheid) at the clinics by the healthcare staff, the other set with FDA/CE approved Nucleic Acid Amplification Tests (NAATs) at the laboratory. Clinical sites and reference laboratories participated in an internal and external quality control programme. Sensitivity, specificity, positive and negative likelihood ratios, positive and negative predictive values for each anatomical site were estimated using a meta-analytic approach.

RESULTS

One thousand seven hundred two MSM were recruited across all clinical sites for a total of 5049 biological specimens. NG and CT were respectively detected in 274 and 287 of samples. Overall, the NG POCT sensitivity and specificity was 91.43% and 99.75% in urine (LR + 372.80, LR- 0.09), 89.68% and 99.55% in rectal specimens (LR + 197.30, LR- 0.10) and 75.87% and 98.77% at the pharynx respectively (LR + 61.94, LR- 0.24). The CT component of the POCT sensitivity was 84.82% and specificity 99.63% in urine (LR + 228.68, LR- 0.15), 78.07% and 99.19% respectively on rectal site (LR + 96.23, LR-0.22), 67.79% and 99.88% respectively at pharyngeal site (LR + 554.89, LR- 0.32). 95.95% of MSM reported to be willing to wait for POCT results and no provider reported difficulties in terms of performance or interpretation of the results of the Xpert CT/NG.

CONCLUSION

Rapid turnaround time, ease of use and high acceptability make the Xpert CT/NG testing system a strategic tool for increasing testing frequency, reaching those not yet tested and offering the possibility of immediate treatment if needed. The assay showed good negative likelihood ratios and confirms its use to rule out CT/NG infections. Sensitivity varied across sites and pathogens. Periodic staff training at the testing sites should be mandatory.

Acceptability, feasibility and cost of point of care testing for sexually transmitted infections among South African adolescents where syndromic management is standard of care

BACKGROUND

Young people (YP) in southern Africa are at substantial risk of HIV and sexually transmitted infections (STIs). Despite the epidemiological and biological link between STIs and HIV transmission and acquisition, infections such as Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) remain widely undiagnosed. Syndromic STI management is the standard of care in low- and middle-income countries (LMICs) despite a high prevalence of asymptomatic infections. We conducted an observational study to explore the acceptability, feasibility, and cost of a STI test-and-treat service for YP in Cape Town.

METHODS

YP attending a mobile clinic (MC) and a youth centre clinic (YC) were offered STI screening. Urine testing for CT and NG using a 90-min molecular point-of-care (POC) test on the GeneXpert platform was conducted and treatment provided. Data were collated on demographics, sexual behaviour, presence of symptoms, uptake of same-day treatment, prevalence of CT/NG, and service acceptability.

RESULTS

Three hundred sixty six participants were enrolled (median age 20, 83% female).57% (209/366) of participants tested positive for either CT (126/366, 34%) or NG (57/366, 16%) or co-infection (26/366, 7%). Clinical symptoms were a poor predictor of GeneXpert diagnosed CT or NG, with a sensitivity of 46.8% and 54.0% for CT and NG respectively. Although half of participants initially chose to receive same day results and treatment, only a third waited for results on the day. The majority of participants (91%) rated the service highly via a post-visit acceptability questionnaire.

CONCLUSION

Curable STIs are highly prevalent in this population. STI screening using POC testing was feasible and acceptability was high. The study provides further impetus for moving policy beyond syndromic management of STIs in South Africa.

Sexually Transmitted Infection Point-of-Care Testing in Resource-Limited Settings: A Narrative Review Guided by an Implementation Framework

ABSTRACT

Most sexually transmitted infections (STIs) are acquired in resource-limited settings (RLSs) where laboratory diagnostic access is limited. Advancements in point-of-care testing (POC) technology have the potential to bring STI testing to many RLSs. We define POC as performed near the patient and with results readily available to inform clinical practice. The World Health Organization Special Programme for Research and Training in Tropical Diseases further outlines desirable POC characteristics with the REASSURED criteria.Despite advantages related to immediate test-and-treat care, integrating POC into RLS health care systems can present challenges that preclude reliance on these tests. In 2018, we incorporated molecular near-POC for chlamydia, gonorrhea, and trichomoniasis and SDBioline treponemal immunochromatographic testing confirmed by rapid plasma reagin for syphilis diagnosis at the Mbarara University of Science and Technology Research Laboratory in rural southwestern Uganda. We describe our experiences with STI POC as a case example to guide a narrative review of the field using the Consolidated Framework for Implementation Research as a conceptual framework.Although POC and near-POC are described as easy to use, the challenges of limited person-power, health care processes, limited infrastructure/resources, high costs, and quality control obstacles can impede the impact of these tests. Increased investment in operators, training, and infrastructure, restructuring health care systems to accommodate increased POC access, and optimizing costs are all crucial to the successful implementation of STI POC in RLS. Expanded STI POC in RLS will increase access to accurate diagnoses, appropriate treatment, and engagement in partner notification, treatment, and prevention efforts.

The impact of COVID-19 pandemic on technologic and process innovation in point-of-care diagnostics for sexually transmitted infections

The STI diagnostic landscape of FDA cleared tests for use at point-of-care (POC), as well as those emergency use authorized for COVID-19 are reviewed; some of these COVID-19 diagnostics may have platform potential as STI diagnostics. Finally, process innovation is described with self-collection and hub-and-spoke mail-in to reference lab models. Movement of Clinical Laboratory Improvement Amendments (CLIA)-waived POC tests to over-the-counter formats will make tests more accessible to consumers. Together with public health messaging, these measures could accelerate STI and COVID-19 syndemic diagnostic solutions.

Improving Management of Suspected Chlamydia and Gonorrhea in Adolescents with a Rapid Diagnostic Test

We aimed to determined the impact of an intervention using rapid chlamydia (CT)/gonorrhea (GC) testing on reducing unnecessary antibiotic use, undertreatment of CT and/or GC, and length of stay (LOS) in an urban safety-net pediatric emergency department.

Methods

Before 2020, we tested for CT/GC using a batched nucleic acid amplification test, with results available the following day. Starting in January 2020, we implemented rapid nucleic acid amplification test. Our primary outcome variables were undertreatment and overtreatment. We defined undertreatment as GC and/or CT-positive patients who did not receive appropriate treatment. We defined overtreatment as GC or CT-negative patients who received antibiotics. The balancing measure was the LOS.

Results

There were 758 patients evaluated in the preimplementation period (2019), 612 in the implementation period (2020), and 626 in the postimplementation period (2021). Postimplementation, overtreatment decreased from 18.4% to 8.1%. Undertreatment did not differ by period but was less common among those tested with rapid versus standard testing (12.7% versus 9.9%, P = 0.05). Median LOS increased from 166 minutes (preimplementation) to 187 minutes (implementation) and 202 minutes (postimplementation; P < 0.001).

Conclusions

Rapid CT/GC testing reduced unnecessary antibiotic use but increased LOS due to patients waiting for the test results before being discharged. Given the rapid increases in CT/GC rates and antimicrobial resistance, health systems should consider implementing rapid testing to appropriately direct antimicrobials to patients most likely to benefit.

Chlamydia trachomatis as a Current Health Problem: Challenges and Opportunities

Chlamydia is one of the most common sexually transmitted bacterial infections (STIs) worldwide. It is caused by Chlamydia trachomatis (CT), which is an obligate intracellular bacterium. In some cases, it can occur in coinfection with other parasites, increasing the pathologic potential of the infection. The treatment is based on antibiotic prescription; notwithstanding, the infection is mostly asymptomatic, which increases the risk of transmission. Therefore, some countries have implemented Chlamydia Screening Programs in order to detect undiagnosed infections. However, in Portugal, there is no CT screening plan within the National Health Service. There is no awareness in the general healthcare about the true magnitude of this issue because most of the methods used are not Nucleic Acid Amplification Technology-based and, therefore, lack sensitivity, resulting in underreporting infection cases. CT infections are also associated with possible long-term severe injuries. In detail, persistent infection triggers an inflammatory milieu and can be related to severe sequels, such as infertility. This infection could also trigger gynecologic tumors in women, evidencing the urgent need for cost-effective screening programs worldwide in order to detect and treat these individuals adequately. In this review, we have focused on the success of an implemented screening program that has been reported in the literature, the efforts made concerning the vaccine discovery, and what is known regarding CT infection. This review supports the need for further fundamental studies in this area in order to eradicate this infection and we also suggest the implementation of a Chlamydia Screening Program in Portugal.

Community engagement on-site rapid test for chlamydia and gonorrhea among men who have sex with men: a pioneering study in Guangzhou, China

Background

Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) infections are prevalent among men who have sex with men (MSM) in China. However, compared to syphilis and HIV, the testing rate for chlamydia and gonorrhea remains low. The purpose of this pilot study was to evaluate the feasibility for conducting rapid nucleic acid test for chlamydia and gonorrhea in MSM community-based organizations (CBO).

Method

We recruited our participants through an MSM CBO where free HV and syphilis testing were routinely provided. We collected data including social-demographic background, sexual history, chlamydia and gonorrhea testing history, and reasons for accepting this on-site rapid testing. Urine and/or anorectal swab samples were collected and tested for chlamydia and gonorrhea on-site and the testing results were delivered in about 1.5 h. Positive cases received on-site free treatment.

Results

From August 2020 to October 2020, 634 MSM visited the CBO for syphilis and HIV testing and 158 (158/634, 24.9%) accepted the on-site chlamydia and gonorrhea rapid test, 135 were finally enrolled. The positive rate fo chlamydia was 16.3% (22/135) and 3.0% (4/135) for gonorrhea, respectively. Only 19.3% participants had previously undergone chlamydia and gonorrhea testing and 68.9% (93/135) participants reported that they had heard of gonorrhea, 47.4% (64/135) had heard of chlamydia. The main reason for testing was “free for charge” (66.2%), followed by “convenient, ‘shorter waiting time” (45.2%) and “had high-risk sexual behavior recently” (16.3%).

Conclusions

This pilot study showed that the chlamydia and gonorrhea infection rate remains high among MSM, while the testing rate was low. On-site rapid testing is feasible and potentially preferred by MSM.

Sexually transmitted infection screening to prevent adverse birth and newborn outcomes: study protocol for a randomized-controlled hybrid-effectiveness trial

Background

Sexually transmitted infections (STIs) during pregnancy are associated with adverse birth outcomes, including preterm birth, low birth weight, perinatal death, and congenital infections such as increased mother-to-child HIV transmission. Prevalence of STIs among pregnant women in South Africa remains high, with most women being asymptomatic for their infection(s). Unfortunately, most STIs remain undetected and untreated due to standard practice syndromic management in accordance with World Health Organization (WHO) guidelines. Although lab-based and point-of-care molecular tests are available, optimal screening strategies during pregnancy, their health impact, and cost-effectiveness are unknown.

Methods

We will implement a 3-arm (1:1:1) type-1 hybrid effectiveness-implementation randomized-controlled trial (RCT). We will enroll 2500 pregnant women attending their first antenatal care (ANC) visit for their current pregnancy at participating health facilities in Buffalo City Metro District, Eastern Cape Province, South Africa. Participants allocated to arms 1 and 2 (intervention) will receive GeneXpert® point-of-care diagnostic testing for Neisseria gonorrhoeae, Chlamydia trachomatis, and Trichomonas vaginalis, with same-day treatment for detected infection(s). Arm 1 will additionally receive a test-of-cure 3 weeks post-treatment, while Arm 2 will receive a repeat test at 30–34 weeks’ gestation. Those allocated to Arm 3 will receive syndromic management (standard-of-care). The RE-AIM framework will be used to guide collection of implementation indicators to inform potential future scale up. Primary outcome measures include (1) frequency of adverse birth outcomes among study arms, defined by a composite measure of low birth weight and pre-term delivery, and (2) change in STI prevalence between baseline and birth outcome among intervention arms and compared to standard-of-care. Estimates and comparative costs of the different screening strategies relative to standard-of-care and the costs of managing adverse birth outcomes will be calculated. Cost-effectiveness will be assessed per STI and disability-adjusted life year averted.

Discussion

This trial is the first RCT designed to identify optimal, cost-effective screening strategies that decrease the burden of STIs during pregnancy and reduce adverse birth outcomes. Demonstrating the impact of diagnostic screening and treatment, compared to syndromic management, on birth outcomes will provide critical evidence to inform changes to WHO guidelines for syndromic management of STIs during pregnancy.

Trial registration

ClinicalTrials.gov NCT04446611. Registered on 25 June 2020.

Limited-resource preparable chitosan magnetic particles for extracting amplification-ready nucleic acid from complex biofluids

Extraction and concentration of pure nucleic acid from complex biofluids are the prerequisite for nucleic acid amplification test (NAAT) applications in pathogen detection, biowarfare prevention, and genetic diseases. However, conventional spin-column mediated nucleic acid extraction is constricted by the requirement for costly power-intensive centralized lab infrastructure, making it unsuitable for limited-resource settings. Significant progress in lab-on-a-chip devices or cartridges (e.g., Cepheid GeneXpert®) that integrate nucleic acid extraction and amplification has been made, but these approaches either require additional equipment or are costly. Similarly, their complexities make them difficult to fabricate in low-resource settings by the end-user themselves. The application of magnetic particles such as silica-coated iron oxide beads for nucleic acid extraction is relatively instrument-free, rapid, user-friendly, and amenable to automation. But, they rely on hazardous chaotropic salt chemistry and ethanol desalting that could limit their efficacy for downstream NAATs. Recent advances in several types of novel material (e.g., polyamine) coated magnetic bead-based chaotropic salt-free extraction methods offer a possible solution to this problem. However, these materials also involve multistep synthesis impermissible in limited-resource settings. To offer a possible instrument-free magnetic particle-based nucleic acid extraction doable at limited-resource settings, we investigated the nucleic acid capture ability of two chitosan-coated magnetic particles that are preparable by minimally trained personnel using only a water bath and a magnetic stirrer within 6-8 h. We quantitatively probed the efficiency of the passive (without any electrical shaking or vortex-aided) DNA magnetocapture (i.e., binding to chitosan magnetic particles, physical separation from its sample of origin, and release from the particles) using UV₂₆₀. To explore their suitability towards clinically relevant sensitive downstream NAATs, 100-1000 copies (i.e., in the order of zeptomole) of Escherichia coli (E. coli) or human genomic DNA from aqueous solution, crude cell lysate, and fetal bovine serum were extracted by them and then successfully detected using quantitative real-time loop-mediated isothermal amplification (LAMP) or real-time polymerase chain reaction (PCR). Alongside, their suitability with gel-based LAMP, colorimetric LAMP, and in situ (on beads) LAMP was also probed. The required optimization of the amplification methods has been discussed. Overall, the turnaround time for the magnetocapture combined with NAAT was 1.5-2 h and is thus expected to aid in rapid clinical decision making. With the ease of preparation, reproducibility, and compatibility with downstream NAATs, we anticipate that these magnetic particles would facilitate the expansion and decentralization of nucleic acid-based diagnosis for limited-resource settings.

AAUS guideline for chlamydial urethritis

Urogenital chlamydial infection is the most common sexually transmitted infection. Many cases of chlamydial infection are reported worldwide every year. Genital chlamydial infection in women can also cause obstetric issues, including infertility and miscarriage. For that purpose, appropriate care should be conducted with the latest knowledge. Only few guidelines come from Asian countries. The Asian Association of Urinary Tract Infection and Sexually Transmitted Infection (AAUS) belonging to the Urological Association of Asia (UAA) had developed the guidelines regarding chlamydial urethritis. We have collected the feedback and updated the guidelines which is now submitted for consideration of publication. In addition to the levels of evidence, the recommendation grades were defined using the modified GRADE methodology. Herein, we present the new edition of the UAA-AAUS guidelines for chlamydial urethritis.

A Narrative Review of Where We Are With Point-of-Care Sexually Transmitted Infection Testing in the United States

BACKGROUND

Point-of-care (POC) tests enable immediate diagnosis and targeted treatment of sexually transmitted infections (STIs), which could accelerate control of ongoing epidemics. Although older nucleic acid amplification tests have improved the accuracy of laboratory-based tests for STIs, newer POC tests can facilitate control efforts. We sought to review the performance and time to result of POC assays for STIs in the last 10 years.

METHODS

The authors performed a PubMed, US National Library of Medicine, National Center for Biotechnology Information search for POC tests for STIs or sexually transmitted diseases.

RESULTS

Diagnostic technology for POC assays for STIs has achieved high sensitivity and specificity (>90%) using recent molecular advances in the last 10 years. Three POC tests for chlamydia and gonorrhea and 2 for trichomonas have been cleared by the Food and Drug Administration and can provide rapid results during the clinical encounter. Two POC assays for syphilis are now cleared by the Food and Drug Administration. Other similar POC assays are in development. These "fast followers" have faster time to result and will extend the diagnostic armamentarium at POC.

CONCLUSIONS

New technology has improved the performance accuracy of STI POC diagnostics. Innovation in device format has resulted in accurate POC assays, which can decrease the time to result and accelerate the detection and treatment of STIs during the clinical encounter. The full implementation potential of these newer tests will depend on the ability of these tests to achieve Clinical Laboratory Improvement Amendments-waived status so they can be performed by nonlaboratorians with no previous training.

A portable magnetofluidic platform for detecting sexually transmitted infections and antimicrobial susceptibility

Effective treatment of sexually transmitted infections (STIs) is limited by diagnostics that cannot deliver results rapidly while the patient is still in the clinic. The gold standard methods for identification of STIs are nucleic acid amplification tests (NAATs), which are too expensive for widespread use and have lengthy turnaround times. To address the need for fast and affordable diagnostics, we have developed a portable, rapid, on-cartridge magnetofluidic purification and testing (PROMPT) polymerase chain reaction (PCR) test. We show that it can detect Neisseria gonorrhoeae, the pathogen causing gonorrhea, with simultaneous genotyping of the pathogen for resistance to the antimicrobial drug ciprofloxacin in <15 min. The duplex test was integrated into a low-cost thermoplastic cartridge with automated processing of penile swab samples from patients using magnetic beads. A compact instrument conducted DNA extraction, PCR, and analysis of results while relaying data to the user via a smartphone app. This platform was tested on penile swab samples from sexual health clinics in Baltimore, MD, USA (n = 66) and Kampala, Uganda (n = 151) with an overall sensitivity and specificity of 97.7% (95% CI, 94.7 to 100%) and 97.6% (95% CI, 94.1 to 100%), respectively, for N. gonorrhoeae detection and 100% concordance with culture results for ciprofloxacin resistance. This study paves the way for delivering accessible PCR diagnostics for rapidly detecting STIs at the point of care, helping to guide treatment decisions and combat the rise of antimicrobial resistant pathogens.

Self-obtained vaginal swabs are not inferior to provider-performed endocervical sampling for emergency department diagnosis of Neisseria gonorrhoeae and Chlamydia trachomatis

OBJECTIVE

Provider-performed endocervical sampling (PPES) in the diagnosis of Neisseria gonorrhoeae (NG) and Chlamydia trachomatis (CT) may be difficult to perform in a busy emergency department (ED) due to patient preference, availability of the pelvic examination room, or provider availability. Our objective was to assess if self-obtained vaginal swabs (SOVS) were noninferior to PPES in the ED diagnosis of NG/CT using a rapid nucleic acid amplification test (NAAT).

METHODS

We conducted a prospective observational cohort study in a single ED. Participants were adult female English- and Spanish-speaking patients in whom the ED provider felt that NG/CT testing was warranted. Each patient had SOVS and PPES performed. For SOVS, a research associate reviewed a one-page handout describing the procedure but gave no other assistance. Patients answered survey questions regarding acceptability of SOVS and symptomatology. We established a minimum sensitivity of 90% for SOVS to be considered clinically noninferior to standard PPES.

RESULTS

A total of 533 patients completed enrollment and answered survey questions, 515 of whom had laboratory results for both SOVS and PPES. There were 86 patients with a positive result: 29 with NG, 47 with CT, and 10 with coinfection. SOVS had a sensitivity of 95% (95% confidence interval = 88% to 99%) for the detection of NG/CT when compared to PPES. SOVS were felt to be an acceptable collection method in 93% of patients and 75% preferred SOVS to PPES.

CONCLUSION

SOVS are noninferior to PPES in NG/CT diagnosis using a rapid NAAT in ED patients and surveys indicate high patient acceptability.

Comparison of methods for the detection of Neisseria gonorrhoeae from South African women attending antenatal care

The detection of Neisseria gonorrhoeae using culture assays is challenging. This study aims to compare different assays for the detection of N. gonorrhoeae. This cross-sectional study was conducted at King Edward VIII Hospital and included 307 antenatal attendees, each willing to provide two endocervical swabs. The first swab was used for culture identification of N. gonorrhoeae, and the second swab was processed for the detection of the pathogen by the TaqMan quantitative polymerase chain reaction (qPCR) assay, an in-house 16S ribosomal RNA (rRNA) PCR and PCR detection of the opa gene. Culture and the nucleic acid amplification assays were each used as comparator tests in the analysis. Sensitivity and specificity were calculated using RS Studio. The prevalence of N. gonorrhoeae was 7.8%. When compared to the TaqMan assay, the 16S rRNA PCR exhibited the highest sensitivity of 62%, with a substantial level of agreement (kappa level of agreement: 0.60), followed by the opa PCR (38%) with a moderate level of agreement (0.52) and culture exhibiting the lowest sensitivity of 25% with a fair level of agreement (0.38). The diagnostic accuracy of all the assays was >90%. The TaqMan qPCR assay has the ability to serve as a future diagnostic assay for the detection of N. gonorrhoeae.

Uptake of and factors associated with testing for sexually transmitted infections in community-based settings among youth in Zimbabwe: a mixed-methods study

BACKGROUND

The prevalence of sexually transmitted infections (STIs) among youth is high in sub-Saharan Africa. We investigated the uptake of testing for and prevalence of Chlamydia trachomatis (chlamydia) and Neisseria gonorrhoeae (gonorrhoea) infections among youth in community-based settings in Zimbabwe, and explored the facilitators and barriers to testing.

METHODS

This study was nested within a cluster randomised trial of community-based delivery of integrated HIV and sexual and reproductive health services for youth aged 16-24 years. Chlamydia and gonorrhoea testing via urine samples using the Xpert CT/NG test was offered in the four intervention clusters in Harare, Zimbabwe. Factors associated with testing uptake were investigated in a subset of participants (n=257) using hierarchical multivariate logistic regression. In-depth interviews with a separate purposively selected sample (n=26) explored facilitators and barriers to STI testing and partner notification and were analysed using thematic analysis.

FINDINGS

Between June 1, 2019, and Jan 31, 2020, there were 6200 attendances by 4440 participants (78·2% women, 21·8% men) median age 20·3 (IQR 17·9-22·8) years. 1478 participants had 1501 tests done, and 248 tests were positive and 1253 tests were negative for chlamydia or gonorrhoea, or both. STI test uptake was 33·3% (95% CI 31·9-34·7), increasing from 11·7% in June, 2019, to 37·1% in January, 2020. The prevalence of chlamydia or gonorrhoea, or both, was 16·5% (95% CI 14·7-18·5; 248 of 1501), with only seven participants (3%) showing symptoms. The overall yield of testing was 4·0% (95% CI 3·5-4·5; 248 of 6200). Uptake was associated with having symptoms (adjusted odds ratio [OR] 14·8, 95% CI 1·66-132·07) and negatively associated with being single (adjusted OR 0·33, 95% CI 0·13-0·84) or having a boyfriend or girlfriend (adjusted OR 0·19, 95% CI 0·087-0·43) compared with being married, and being a student compared with being employed (adjusted OR 0·26, 95% CI 0·10-0·68). Perceived risk and symptoms of STIs were motivators for testing whereas misinformation, anticipated stigma, and concern about confidentiality were barriers.

INTERPRETATION

The prevalence of chlamydia or gonorrhoea, or both, was high among youth but only a minority were symptomatic. Therefore most infections would remain untreated without access to STI testing. Provision of education, counselling, and confidentiality are essential to improve uptake and acceptability of STI testing.

FUNDING

Wellcome Trust.

Potential for Point-of-Care Tests to Reduce Chlamydia-associated Burden in the United States: A Mathematical Modeling Analysis

Background

Point-of-care testing (POCT) assays for chlamydia are being developed. Their potential impact on the burden of chlamydial infection in the United States, in light of suboptimal screening coverage, remains unclear.

Methods

Using a transmission model calibrated to data in the United States, we estimated the impact of POCT on chlamydia prevalence, incidence, and chlamydia-attributable pelvic inflammatory disease (PID) incidence, assuming status quo (Analysis 1) and improved (Analysis 2) screening frequencies. We tested the robustness of results to changes in POCT sensitivity, the proportion of patients getting treated immediately, the baseline proportion lost to follow-up (LTFU), and the average treatment delay.

Results

In Analysis 1, high POCT sensitivity was needed to reduce the chlamydia-associated burden. With a POCT sensitivity of 90%, reductions from the baseline burden only occurred in scenarios in which over 60% of the screened individuals would get immediate treatment and the baseline LTFU proportion was 20%. With a POCT sensitivity of 99% (baseline LTFU 10%, 2-week treatment delay), if everyone were treated immediately, the prevalence reduction was estimated at 5.7% (95% credible interval [CrI] 3.9–8.2%). If only 30% of tested persons would wait for results, the prevalence reduction was only 1.6% (95% CrI 1.1–2.3). POCT with 99% sensitivity could avert up to 12 700 (95% CrI 5000–22 200) PID cases per year, if 100% were treated immediately (baseline LTFU 20% and 3-week treatment delay). In Analysis 2, when POCT was coupled with increasing screening coverage, reductions in the chlamydia burden could be realized with a POCT sensitivity of 90%.

Conclusions

POCT could improve chlamydia prevention efforts if test performance characteristics are significantly improved over currently available options.

Evaluation of the Diagnostic Efficacy of Xpert CT/NG for Chlamydia trachomatis and Neisseria gonorrhoeae

BACKGROUND

Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) are widely spread across the world. Asymptomatic or inconspicuous CT/NG infections are difficult to diagnose and treat. Traditional methods have the disadvantages of low detection rate, inaccurate results, and long detection time. However, Xpert CT/NG makes up for the aforementioned shortcomings and has research value and popularization significance.

METHODS

PubMed, Embase, Cochrane Library, and Web of Science were systematically searched, and studies were screened using Xpert CT/NG for diagnosing CT/NG. QUADAS-2 was used to evaluate the quality of the eligible studies. Then, two groups of researchers independently extracted data from these studies. Meta-analyses of sensitivity (SEN), specificity (SPE), positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and the area under the curve (AUC) of the summary receiver operating characteristic (SROC) curve were conducted using Meta-DiSc 1.4. Finally, Deek's funnel plots were made using Stata 12.0 to evaluate publication bias.

RESULTS

14 studies were identified, and 46 fourfold tables were extracted in this meta-analysis. The pooled SEN, SPE, PLR, NLR, DOR, and AUC in diagnosing CT were 0.94 (95% confidence interval (CI): 0.93-0.95), 0.99 (95% CI: 0.99-1.00), 97.17 (95% CI: 56.76-166.32), 0.07 (95% CI: 0.04-0.12), 1857.25 (95% CI: 943.78-3654.86), and 0.9960, respectively. The pooled SEN, SPE, PLR, NLR, DOR, and AUC in diagnosing NG were 0.95 (95% CI: 0.93-0.96), 1.00 (95% CI: 1.00-1.00), 278.15 (95% CI: 152.41-507.63), 0.08 (95% CI: 0.06-0.12), 4290.70 (95% CI: 2161.78-8516.16), and 0.9980, respectively.

CONCLUSIONS

Xpert CT/NG had high diagnostic sensitivity and specificity for CT and NG. However, more evidence is required to confirm that Xpert CT/NG might serve as the primary method for detecting CT and NG and even the gold standard for diagnosis in the future.

Genotypic determinants of fluoroquinolone and macrolide resistance in Neisseria gonorrhoeae

Background High rates of antimicrobial resistance (AMR) in Neisseria gonorrhoeae hinder effective treatment, but molecular AMR diagnostics may help address the challenge. This study aimed to appraise the literature for resistance-associated genotypic markers linked to fluoroquinolones and macrolides, to identify and review their use in diagnostics.

METHODS

Medline and EMBASE databases were searched and data pooled to evaluate associations between genotype and phenotypic resistance. The minimum inhibitory concentration (MIC) cut-offs were ≤ 0.06 mg L-1 for non-resistance to ciprofloxacin and ≤ 0.5 mg L-1 for non-resistance to azithromycin.

RESULTS

Diagnostic accuracy estimates were limited by data availability and reporting. It was found that: 1) S91 and D95 mutations in the GyrA protein independently predicted ciprofloxacin resistance and, used together, gave 98.6% (95% confidence interval (CI) 98.0-99.0%) sensitivity and 91.4% (95%CI 88.6-93.7%) specificity; 2) the number of 23S rRNA gene alleles with C2611T or A2059G mutations was highly correlated with azithromycin resistance, with mutation in any allele giving a sensitivity and specificity of 66.1% (95%CI 62.1-70.0%) and 98.9% (95%CI 97.5-99.5%) respectively. Estimated negative (NPV) and positive predictive values (PPV) for a 23S rRNA diagnostic were 98.6% (95%CI 96.8-99.4%) and 71.5% (95%CI 68.0-74.8%) respectively; 3) mutation at amino acid position G45 in the MtrR protein independently predicted azithromycin resistance; however, when combined with 23S rRNA, did not improve the PPV or NPV.

CONCLUSIONS

Viable candidates for markers of resistance detection for incorporation into diagnostics were demonstrated. Such tests may enhance antibiotic stewardship and treatment options.

Patterns of Screening, Infection, and Treatment of Chlamydia trachomatis and Neisseria gonorrhea in Pregnancy

OBJECTIVE

To describe factors associated with not being tested for Chlamydia trachomatis and Neisseria gonorrhea infection during pregnancy and for testing positive and to describe patterns of treatment and tests of reinfection.

METHODS

We conducted a retrospective cohort study of women who delivered at an urban teaching hospital from July 1, 2016 to June 30, 2018. Women with at least one prenatal care or triage visit were included. The index delivery was included for women with multiple deliveries. We used logistic regression to analyze factors associated with not being tested and for testing positive for these infections in pregnancy. Cox proportional hazards models were used to examine factors associated with time to treatment and tests of reinfection. We reviewed medical records to determine reasons for delays in treatment longer than 1 week.

RESULTS

Among 3,265 eligible deliveries, 3,177 (97%) women were tested during pregnancy. Of these, 370 (12%) tested positive (287 chlamydia, 35 gonorrhea, 48 both), and 15% had repeat infections. Prenatal care adequacy and insurance status were risk factors for not being tested. Age, race and ethnicity, alcohol use, and sexually transmitted infection history were associated with testing positive. Time to treatment ranged from 0 to 221 days, with the majority (55%) of patients experiencing delays of more than 1 week. Common reasons for delays included lack of clinician recognition and follow-up of abnormal results (65%) and difficulty contacting the patient (33%).

CONCLUSION

Traditional risk factors are associated with increased risk of infection during pregnancy. Prenatal care adequacy and insurance status were associated with the likelihood of being tested. Delays in treatment and tests of reinfection were common. Point-of-care testing and expedited partner therapy should be explored as ways to improve the management of these infections in pregnancy.

Rapid polymerase chain reaction test for the early diagnosis of gonococcal keratoconjunctivitis

PURPOSES

A case of gonococcal keratoconjunctivitis rapidly diagnosed by a vaginal swab PCR Xpert® CT/NG assay.

METHODS

Case report.

RESULTS

A 26-year-old woman presented to our emergency department with severe perilimbal stromal melting in both eyes and profuse purulent discharge for one day. Upon emergent ocular consultation, gonococcal keratoconjunctivitis was suspected. A vaginal swab was sent for rapid PCR Xpert® CT/NG assay which reported positive Neisseria gonorrhoeae (NG) and Chlamydia Trachoma (CT) DNA detection within 90 min. Due to the rapid diagnosis, adequate medical intervention with ceftriaxone injection was administered. Gonococcal keratitis with stromal melting was stabilized within 5 days of presentation. The patient was discharged with complete epithelial healing by the 8th day. However, 10 weeks after discharge, inadvertent rubbing of the left eye resulted in corneal perforation with iris prolapse. Lamellar keratoplasty with corneal patch graft was performed with amniotic membrane grafting. Xpert® CT/NG assay was performed again with conjunctival swab for recurring mild eye discharge. Both NG and CT were negative. The patient thus stabilized with no further complications.

CONCLUSIONS

Rapid stromal melting can occur with un-diagnosed or delayed diagnosis of gonorrhea with ocular involvement. Speedy and accurate diagnosis by the highly sensitive and specific Xpert® CT/NG assay can provide early definite diagnosis for prompt treatment in prevention of gonococcal infection induced corneal perforations.

The Laboratory Diagnosis of Neisseria gonorrhoeae: Current Testing and Future Demands

The ideal laboratory test to detect Neisseria gonorrhoeae (Ng) should be sensitive, specific, easy to use, rapid, and affordable and should provide information about susceptibility to antimicrobial drugs. Currently, such a test is not available and presumably will not be in the near future. Thus, diagnosis of gonococcal infections presently includes application of different techniques to address these requirements. Microscopy may produce rapid results but lacks sensitivity in many cases (except symptomatic urogenital infections in males). Highest sensitivity to detect Ng was shown for nucleic acid amplification technologies (NAATs), which, however, are less specific than culture. In addition, comprehensive analysis of antibiotic resistance is accomplished only by in vitro antimicrobial susceptibility testing of cultured isolates. As a light at the end of the tunnel, new developments of molecular techniques and microfluidic systems represent promising opportunities to design point-of-care tests for rapid detection of Ng with high sensitivity and specificity, and there is reason to hope that such tests may also provide antimicrobial resistance data in the future.

Performance of the Atlas Genetics Rapid Test for Chlamydia trachomatis and Women's Attitudes Toward Point-Of-Care Testing

PURPOSE

This study compared performance of the Atlas io polymerase chain reaction-based, point-of-care (POC) assay for Chlamydia trachomatis (CT), to Aptima Combo 2, a standard of care nucleic acid amplification assay, and evaluated patient attitudes toward POC testing.

METHODS

Women 14 years or older undergoing CT screening/testing were recruited from Teen Health Center and a sexually transmitted disease clinic. Participants provided self-obtained vaginal swabs for testing with the Atlas io and Aptima Combo 2, and completed questionnaires assessing attitudes toward POC testing.

RESULTS

Of 296 women recruited, 284 (192 from sexually transmitted disease clinic, 92 from Teen Health Center) had Aptima Combo 2 and Atlas io results available; 273 completed the questionnaire. Average age was 27.4 years (SD, 10.8 years). Sensitivity and specificity of the Atlas io test were 83.9% (26/31 specimens; 95% confidence interval [CI], 70.9-96.8%) and 98.8% (250/253 specimens; 95% CI, 97.5-100%), respectively. When specimens with discrepant results were included in the analyses, adjudicated sensitivity and specificity were 92.9% (26/28 specimens; 95% CI, 83.3 to 100%) and 98.8% (253/256 specimens; 95% CI, 97.5 to 100%), respectively.A majority (70%) of women preferred to collect vaginal self-swab if a POC test were available. Most (61%) were willing to wait up to 20 minutes, and 26% were willing to wait up to 40 minutes for results, if they could be treated before leaving clinic.

CONCLUSIONS

A POC polymerase chain reaction test detecting CT had high sensitivity and specificity when testing prospective, vaginal swab samples. Availability of CT results during patients' visits may decrease time to treatment.

Impact of specimen storage temperature and time on the implementation of GeneXpert® testing for sexually transmitted infections in resource-constraint settings

Implementation of routine laboratory diagnostics is imperative to address the high burden of sexually transmitted infections (STI) in Sub-Saharan Africa. We demonstrate that logistical challenges of specimen storage, temperature and transport time are unlikely to impact on performance of routine STI diagnostics using the GeneXpert® platform implemented in these settings.

Meta-analysis of the Cepheid Xpert® CT/NG assay for extragenital detection of Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) infections

Background Most studies evaluating extragenital testing performance for Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) detection by the Xpert® CT/NG show high per cent agreement with comparison assays; however, the precision around positive per cent agreement is low and thus the values that have been reported are not highly informative. Therefore, a systematic review was conducted and data from five studies were combined to better assess positive per cent agreement.

METHODS

The literature indexed on PubMed.gov was searched. Included studies were those that were an evaluation of the Xpert CT/NG assay with rectal and/or pharyngeal specimen types compared with another nucleic acid amplification test (NAAT), the Aptima transcription mediated amplification assay. A full Bayesian method was used for bivariate fixed-effect meta-analysis of positive and negative per cent agreement and pooled estimates (and 95% confidence intervals (CI)) were presented for each.

RESULTS

The pooled positive and negative per cent agreement for detection of CT in rectal specimens was 89.72% (95% CI: 84.97%, 93.64%) and 99.23% (95% CI: 98.74%, 99.60%), and in pharyngeal specimens, they were 89.96% (95% CI: 66.38%, 99.72%) and 99.62% (95% CI: 98.95%, 99.95%) respectively. For NG detection in rectal specimens, the pooled positive and negative per cent agreement was 92.75% (95% CI: 87.91%, 96.46%) and 99.75% (95% CI: 99.46%, 99.93%), and in pharyngeal specimens, they were 92.51% (95% CI: 85.84%, 97.18%) and 98.56% (95% CI: 97.69%, 99.23%) respectively.

CONCLUSIONS

It was found that the Xpert CT/NG assay performed similarly to the Aptima transcription mediated amplification assay for the detection of CT and NG in extragenital specimens. The Xpert assay has the benefit of providing faster results at the point-of-care, thus reducing the turnaround time for results, potentially enabling same-day treatment.

A diagnostic evaluation of a molecular assay used for testing and treating anorectal chlamydia and gonorrhoea infections at the point-of-care in Papua New Guinea

OBJECTIVES

Papua New Guinea has among the highest prevalences of sexually transmissible infections (STIs) globally with no services able to accurately test for anorectal Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) infections. Here we prospectively evaluated the diagnostic performance of a molecular CT/NG assay used at the point-of-care (POC) with the aim of enhancing anorectal STI screening and same-day treatment.

METHODS

Men who have sex with men, transgender women and female sex workers taking part in Papua New Guinea's first large-scale biobehavioural study were enrolled and asked to provide a self-collected anorectal swab for POC GeneXpert CT/NG testing. Same-day treatment was offered if positive. A convenience sample of 396 unique and randomly selected samples were transported to Australia for comparison using the Cobas 4800 CT/NG test (Roche Molecular Diagnostics, Pleasanton, CA, USA).

RESULTS

A total of 326 samples provided valid results by Cobas whereas 70 samples provided invalid results suggesting inhibition. The positive, negative and overall percentage agreements of GeneXpert CT/NG for the detection of C. trachomatis were 96.7% (95% CI 92.3%-98.9%), 95.5% (95% CI 91.3%-98.0%) and 96.0% (95% CI 93.3%-97.8%), and for N. gonorrhoeae were 93.0% (95% CI 86.1%-97.1%), 100.0% (95% CI 98.3%-100.0%) and 97.8% (95% CI 95.6%-99.1%), respectively.

CONCLUSIONS

The overall rate of agreement between the GeneXpert and Cobas CT/NG assays was high with 96.0% for C. trachomatis and 97.8% for N. gonorrhoeae. Results from this study data suggest that the GeneXpert CT/NG assay is suitable for testing self-collected anorectal specimens at the POC and that same-day treatment was feasible.

Targeted point-of-care testing compared with syndromic management of urogenital infections in women (WISH): a cross-sectional screening and diagnostic accuracy study

BACKGROUND

Sexually transmitted and urogenital infections are typically managed by WHO-recommended syndromic algorithms in resource-poor countries, and presumptively in Europe. However, algorithms for vaginal discharge and lower abdominal pain perform poorly in women. The women's improvement of sexual and reproductive health (WISH) study in Kigali, Rwanda, sought to improve case-finding and infection management in women by introducing point-of-care tests. The main aim was to compare the performance of the WISH algorithms and the WHO vaginal discharge and lower abdominal pain algorithms with gold standard testing.

METHODS

This cross-sectional screening and diagnostic accuracy study recruited women aged 18 years or older with or without urogenital symptoms at risk of acquiring sexually transmitted infections in Kigali, Rwanda. Recruitment activities were implemented by study staff with the help of community mobilisers at health centres, pharmacies, markets, women's organisations, and at "umuganda" community meetings. At the study visit, participants had a face-to-face interview that included questions about current urogenital symptoms. Participants were first asked without prompting (spontaneous reporting), followed by questions about 14 specific symptoms (structural reporting). Next, the WISH algorithms were implemented. All participants had point-of-care tests for bacterial vaginosis (vaginal pH of 5·0 or above) and Trichomonas vaginalis (immunoassay) regardless of symptom reporting. Women with a positive risk score had point-of-care tests for Chlamydia trachomatis and Neisseria gonorrhoea (nucleic acid amplification tests). Vulvovaginal candidiasis was treated presumptively. Nucleic acid amplification tests for C trachomatis, N gonorrhoeae, T vaginalis, bacterial vaginosis, and vulvovaginal candidiasis were the gold standard, and all patients provided swabs for these.

FINDINGS

Participants were recruited between July 5, 2016, and March 14, 2017. 705 participants were enrolled in the study and completed a study visit, and 51 attended 53 additional visits. Prevalence by gold standard testing was 8·5% for C trachomatis, 7·1% for N gonorrhoeae, 16·1% for T vaginalis, 18·1% for bacterial vaginosis, and 8·6% for vulvovaginal candidiasis. The WISH algorithms identified similar numbers of C trachomatis, N gonorrhoeae, and T vaginalis infections, but much higher numbers of bacterial vaginosis and vulvovaginal candidiasis infections. Compared with gold standard testing, the WISH algorithms had a good sensitivity and high specificity for C trachomatis (sensitivity 71·7%, specificity 100%), N gonorrhoeae (sensitivity 76·0%, specificity 100%), and T vaginalis (sensitivity 68·5%, specificity 97·4%), high sensitivity but low specificity for bacterial vaginosis (sensitivity 95·2%, specificity 41·2%), and moderate sensitivity and specificity for vulvovaginal candidiasis (sensitivity 64·4%, specificity 69·4%). The performance of vaginal pH testing for bacterial vaginosis improved by increasing the cutoff to 5·5, followed by confirmatory testing (sensitivity 73·6%, specificity 100%). The WHO algorithms had moderate sensitivity and poor specificity for all infections compared with gold standard testing: C trachomatis sensitivity 58·3%, specificity 44·7%; N gonorrhoeae sensitivity 66·0%, specificity 45·2%; T vaginalis sensitivity 60·4%, specificity 45·6%; bacterial vaginosis sensitivity 61·6%, specificity 46·0%; and vulvovaginal candidiasis sensitivity 74·6%, specificity 50·6%. Two participants attended additional visits because they had a mild allergic reaction to metronidazole. Staff and participants considered point-of-care testing feasible and acceptable.

INTERPRETATION

Point-of-care testing for urogenital infections might improve case-finding and infection management and is feasible in resource-poor settings. Point-of-care tests should be further developed, including those targeting multiple conditions. Additional studies in other populations, including populations with low prevalence of sexually transmitted and urogenital infections, are warranted.

FUNDING

European and Developing Countries Clinical Trials Partnership.

Diagnostic tools for tackling febrile illness and enhancing patient management

Most patients with acute infectious diseases develop fever, which is frequently a reason to visit health facilities in resource-limited settings. The symptomatic overlap between febrile diseases impedes their diagnosis on clinical grounds. Therefore, the World Health Organization promotes an integrated management of febrile illness. Along this line, we present an overview of endemic and epidemic etiologies of fever and state-of-the-art diagnostic tools used in the field. It becomes evident that there is an urgent need for the development of novel technologies to fulfill end-users' requirements. This need can be met with point-of-care and near-patient diagnostic platforms, as well as e-Health clinical algorithms, which co-assess test results with key clinical elements and biosensors, assisting clinicians in patient triage and management, thus enhancing disease surveillance and outbreak alerts. This review gives an overview of diagnostic technologies featuring a platform based approach: (i) assay (nucleic acid amplification technologies are examined); (ii) cartridge (microfluidic technologies are presented); (iii) instrument (various detection technologies are discussed); and at the end proposes a way that such technologies can be interfaced with electronic clinical decision-making algorithms towards a broad and complete diagnostic ecosystem.

WHO laboratory validation of Xpert® CT/NG and Xpert® TV on the GeneXpert system verifies high performances

Effective tests for diagnosis of sexually transmitted infections (STIs), used point of care to inform treatment and management decisions, are urgently needed. We evaluated the analytical sensitivity and specificity of the Xpert^® CT/NG and Xpert^® TV tests, examining 339 samples spiked with phenotypically and/or genetically diverse strains of Neisseria gonorrhoeae, Chlamydia trachomatis, and Trichomonas vaginalis, and other related species that may cross-react. The APTIMA Combo 2 test and APTIMA TV test were used as reference tests. The analytical sensitivity for all three agents in the Xpert^® CT/NG and Xpert^® TV tests was ≤10² genome equivalents/reaction. The analytical specificity of both tests was high. False-positive results were identified in the Xpert^® TV test when challenging with high concentrations of Trichomonas tenax, Trichomonas gallinae, Trichomonas stableri, and Trichomonas aotus. However, the clinical relevance of these cross-reactions can likely be neglected, because these species have not been identified in urogenital samples from humans. In conclusion, the analytical sensitivity and specificity of the user-friendly Xpert^® CT/NG and Xpert^® TV tests on the GeneXpert system were high. The results support the use of specimens from also extra-genital sites, for example, pharynx and rectum. However, appropriate clinical validations are additionally required.

Comparison between DiaPlexQ™ STI6 and GeneFinder™ STD I/STD II multiplex Real-time PCR Kits in the detection of six sexually transmitted disease pathogens

BACKGROUND

The DiaPlexQ™ STI6 Detection Kit (DiaPlexQ; Solgent Co., Ltd., Daejeon, South Korea) is a multiplex real-time PCR assay for the detection of the following sexually transmitted disease (STD) pathogens: Chlamydia trachomatis, Neisseria gonorrhoeae, Mycoplasma hominis, Trichomonas vaginalis, Ureaplasma urealyticum, and Mycoplasma genitalium. We compared the performance of the DiaPlexQ assay with the GeneFinder™ STD I (CT/NG/UU) and STD II (MG/MH/TV) Multiplex Real-time PCR Kits (GeneFinder; Infopia Co., Ltd., Anyang, South Korea).

METHODS

We evaluated the performance of the DiaPlexQ assay in comparison to that of GeneFinder using 1106 clinical specimens (542 genital swabs and 564 urine samples). The analytical performance of the DiaPlexQ assay, including the limit of detection (LOD) and analytical specificity, was evaluated using reference strains.

RESULTS

The positive percent agreement, negative percent agreement, and kappa value between the two assays were 96.6%-99.4%, 98.2%-99.8%, and 0.93%-0.99%, respectively. No cross-reactivity was observed in a collection of 41 different microorganisms and the LOD of the DiaPlexQ assay ranged from 1 to 10 copies/reaction for each microorganism.

CONCLUSION

The DiaPlexQ assay showed comparable performance to that of the GeneFinder assay so that it can be used for the screening and diagnosis of non-viral curable STD pathogens.

Molecular test for chlamydia and gonorrhoea used at point of care in remote primary healthcare settings: a diagnostic test evaluation

OBJECTIVES

A new molecular test for Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) (GeneXpert CT/NG) has been demonstrated to be as accurate as conventional nucleic acid amplification tests (NAAT), but performance has not been evaluated in routine primary care, performed at the point of care by clinicians. We aimed to examine its diagnostic performance when used by clinicians in remote community health services in Australia with high prevalences of CT and NG infection. The trial was registered with the Australian and New Zealand Clinical Trials Registry (#12613000808741) METHODS: At 12 health services, training was provided to 99 clinicians in the use of the GeneXpert CT/NG assay who tested specimens from all patients undergoing STI screening. Specimens were also sent in parallel for conventional laboratory-based NAATs and the concordance of results was evaluated.

RESULTS

Clinicians conducted 2486 tests: CT concordance was 99.4% (95% CI 99.1 to 99.7) with a positive concordance of 98.6% (95% CI 95.9 to 99.7) and negative concordance of 99.5% (95% CI 99.1 to 99.8); NG concordance was 99.9% (95% CI 99.7 to 100.0) with a positive concordance of 100.0% (95% CI 97.5 to 100.0) and negative concordance of 99.9% (95% CI 99.7 to 100.0).

CONCLUSIONS

In this first study reporting routine point-of-care use of GeneXpert CT/NG by primary care clinicians, we found excellent concordance with conventional NAATs. The use of the GeneXpert CT/NG at the point of care could potentially transform management and control of these infections in many endemic settings, including low/middle-income countries.

Inflammatory cytokine biomarkers of asymptomatic sexually transmitted infections and vaginal dysbiosis: a multicentre validation study

OBJECTIVES

Vaginal dysbiosis and STIs are important drivers of the HIV epidemic and reproductive complications. These conditions remain prevalent, partly because most cases are asymptomatic. We have shown that inflammatory cytokines interleukin (IL)-1α, IL-1β and interferon-γ-induced protein (IP)-10 are biomarkers for detecting asymptomatic STIs and vaginal dysbiosis (bacterial vaginosis (BV) or intermediate microbiota). This study aimed to validate the performance of these biomarkers in African women recruited regardless of symptoms.

METHODS

IL-1α, IL-1β and IP-10 were measured in menstrual cup secretions, endocervical, lateral vaginal wall and vulvovaginal swabs from 550 women from Pretoria, Soweto and Cape Town, South Africa and Bondo, Kenya using Luminex and ELISA. STIs were assessed by PCR, BV by Nugent scoring and vaginal microbiota by 16S rRNA sequencing.

RESULTS

Across four study populations and four types of genital specimens, the performance of IL-1α, IL-1β and IP-10 for identification of women with STIs, BV or intermediate microbiota was consistent. Of the genital samples assessed, biomarkers measured in lateral vaginal wall swabs performed best, correctly classifying 76%(95% CI 70% to 81%) of women according to STI, BV or intermediate microbiota status (sensitivity 77%, specificity 71%) and were more accurate than clinical symptoms (sensitivity 41%, specificity 57%) (p=0.0003). Women incorrectly classified as STI/BV positive using the biomarkers had more abundant dysbiosis-associated bacteria, including Prevotella bivia and Gardnerella sp, detected by 16S rRNA sequencing, but not Nugent scoring. Including vaginal pH with the cytokine biomarkers improved the accuracy of the test (82% (95% CI 75% to 88%) correctly classified), although pH alone had poor specificity (61%).

CONCLUSIONS

An inexpensive, point-of-care screening test including IL-1α, IL-1β and IP-10 (and potentially pH) could be used in resource-limited settings to identify women with asymptomatic STIs and dysbiosis. These women could then be referred for aetiological testing, followed by specific treatment.

A reliable and easy to transport quality control method for chlamydia and gonorrhoea molecular point of care testing

Quality control (QC) is an essential component of point-of-care testing programs. In the context of a randomised-controlled trial (TTANGO) using GeneXpert (Xpert) Chlamydia trachomatis and Neisseria gonorrhoeae (CT/NG) point-of-care testing in remote areas of Australia, we aimed to develop and utilise a stable positive control material. Bacterial cultures of CT and NG were resuspended together to provide cycle threshold (Ct) values of approximately 25 cycles for both CT and NG when tested on the Xpert CT/NG assay. These positive control suspensions were dried in aliquots, heat inactivated, and then provided to 12 participating health services as research-only QC samples in kit form. At each service, a QC sample was resuspended and tested each month on the Xpert. QC results, including Xpert Ct values, were analysed from each site over 30 months and we calculated costs per QC sample. Overall, at 12 health services there were 89 QC samples tested (average of 8 tests per site per year). Mean Ct values for the 89 controls samples were 25.25 cycles (SD = 1.15) for CT, 24.04 cycles (SD = 1.400) for one NG target and 23.35 cycles (SD = 1.55) for the other NG target. No significant differences in Ct value for CT or NG controls were observed over a trial period of 30 months. Positive QC samples for research use in a trial of a molecular point-of-care assay were inexpensive to produce and stable when stored at 2-8°C. For routine use, additional requirements such as meeting National Association of Testing Authority (NATA) regulations and Therapeutic Goods Administration (TGA) approval will need to be achieved.

Use of Nucleic Acid Amplification Testing for Diagnosis of Extragenital Sexually Transmitted Infections

Nucleic acid amplification testing (NAAT) is the preferred method to detect Chlamydia trachomatis and Neisseria gonorrhoeae, but no commercial tests are cleared by the U.S. Food and Drug Administration for use with extragenital swab samples. This study evaluated the performance of the Gen-Probe Aptima Combo2 assay (Aptima) and the Cepheid Xpert CT/NG assay (Xpert) to detect C. trachomatis and N. gonorrhoeae in rectal and pharyngeal samples from 224 men and 175 women reporting a history of anal receptive sexual intercourse. Discordant results between the NAATs were repeated using the assays APTIMA CT or APTIMA GC, which target alternate primers, as the confirmatory tests. C. trachomatis was detected from 59 rectal swabs and 8 pharyngeal samples, with 97.7% and 99.5% agreement between the two test systems, respectively. For C. trachomatis, Xpert was 95% sensitive (95% CI, 86 to 99%) and Aptima was 92% sensitive (95% CI, 81 to 97%) from rectal swabs, while both systems were 100% sensitive from pharyngeal samples. N. gonorrhoeae was detected from 30 rectal and 40 pharyngeal samples, with 99.5% and 97.5% agreement between the two test systems. The sensitivity of Xpert for N. gonorrhoeae from rectal swabs was 100% (95% CI, 88 to 100%) versus 93% (95% CI, 78 to 99%) for Aptima. From pharyngeal swab samples, Xpert was 98% sensitive (95% CI, 87 to 99.9%) versus 93% (95% CI, 80 to 98%) for Aptima. For C. trachomatis, neither system was >95% sensitive from the rectum, though both were >99.5% specific. For N. gonorrhoeae, Xpert had higher sensitivity than Aptima, but with more false positives from pharyngeal samples.

Opportunities and barriers to STI testing in community health centres in China: a nationwide survey

BACKGROUND

China has strengthened its primary care workforce and implemented a wide network of community health centres (CHCs). However, STI testing and management are not currently included in the 'Essential Package of Primary Health Care in China'. Legislation change to encourage STI service delivery would be important, but it is also critical to determine if there are also provider-related opportunities and barriers for implementing effective STI programmes through CHCs if future legislation were to change.

METHODS

A national representative survey was conducted between September and December 2015 in a stratified random sample of 180 CHCs based in 20 cities in China. Primary care practitioners (PCPs) provided information on current experiences of STI testing as well as the barriers and facilitators for STI testing in CHCs. Multivariate logistic regression was conducted to determine factors associated with PCPs performing STI testing.

RESULTS

3580 out of 4146 (86%) invited PCPs from 158 CHCs completed the survey. The majority (85%, 95% CI 84% to 87%) of doctors stated that STI testing was an important part of healthcare. However, less than a third (29%, 95% CI 27% to 31%) would perform an STI test if the patients asked. Barriers for performing STI testing included lack of training, concerns about reimbursement, concerns about damage to clinics' reputations and the stigma against key populations. Respondents who reported that they would perform an STI test were likely to be younger, received a bachelor degree or higher, received specific training in STIs, believed that STI test was an important part of healthcare or had resources to perform STI testing.

CONCLUSIONS

There is potential for improving STI management in China through upskilling the primary care workforce in CHCs. Specific training in STIs is needed, and other structural, logistical and attitudinal barriers are needed to be addressed.

Detection of antibiotic resistance is essential for gonorrhoea point-of-care testing: a mathematical modelling study

BACKGROUND

Antibiotic resistance is threatening to make gonorrhoea untreatable. Point-of-care (POC) tests that detect resistance promise individually tailored treatment, but might lead to more treatment and higher levels of resistance. We investigate the impact of POC tests on antibiotic-resistant gonorrhoea.

METHODS

We used data about the prevalence and incidence of gonorrhoea in men who have sex with men (MSM) and heterosexual men and women (HMW) to calibrate a mathematical gonorrhoea transmission model. With this model, we simulated four clinical pathways for the diagnosis and treatment of gonorrhoea: POC test with (POC+R) and without (POC-R) resistance detection, culture and nucleic acid amplification tests (NAATs). We calculated the proportion of resistant infections and cases averted after 5 years, and compared how fast resistant infections spread in the populations.

RESULTS

The proportion of resistant infections after 30 years is lowest for POC+R (median MSM: 0.18%, HMW: 0.12%), and increases for culture (MSM: 1.19%, HMW: 0.13%), NAAT (MSM: 100%, HMW: 99.27%), and POC-R (MSM: 100%, HMW: 99.73%). Per 100 000 persons, NAAT leads to 36 366 (median MSM) and 1228 (median HMW) observed cases after 5 years. Compared with NAAT, POC+R averts more cases after 5 years (median MSM: 3353, HMW: 118). POC tests that detect resistance with intermediate sensitivity slow down resistance spread more than NAAT. POC tests with very high sensitivity for the detection of resistance are needed to slow down resistance spread more than by using culture.

CONCLUSIONS

POC with high sensitivity to detect antibiotic resistance can keep gonorrhoea treatable longer than culture or NAAT. POC tests without reliable resistance detection should not be introduced because they can accelerate the spread of antibiotic-resistant gonorrhoea.

Comparative Evaluation of 2 Nucleic Acid Amplification Tests for the Detection of Chlamydia trachomatis and Neisseria gonorrhoeae at Extragenital Sites

Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) infections are frequently asymptomatic, requiring highly accurate diagnostic tests and proper management to prevent further transmission. We compared two nucleic acid tests, Xpert® CT/NG (Cepheid, Sunnyvale, CA) point-of-care platform and at an offsite clinical laboratory with Aptima Combo 2® (Hologic, Inc., San Diego, CA) assay, for the detection of extragenital infection in patients at an STI clinic in Hollywood, CA.We calculated concordance between the two assays and used the exact binomial method to calculate 95% confidence intervals (CIs) for each specimen type and pathogen.The concordance between the two assays was 97.7% (95% CI: 95.7%,99.0%) for 393 paired CT rectal results, 98.2% (95% CI: 96.4%,99.3%) for 391 paired NG rectal results and 98.4% (95% CI: 96.8%,99.4%) for 448 paired NG pharyngeal results.The performance of Xpert® CT/NG assay in point-of-care testing in extragenital specimens was highly similar to the laboratory-based platform.

Prevalence and risk factors associated with sexually transmitted infections (STIs) among women of reproductive age in Swaziland

BACKGROUND

Sexually transmitted infections (STIs) remain an important public health problem with approximately half a billion new cases annually among persons aged 15-49 years. Epidemiological data on STIs among women of reproductive age in Swaziland are limited. The availability of epidemiological data on STIs and associated risk factors in this population is essential for the development of successful prevention, diagnosis and management strategies in the country. The study aimed to determine the prevalence and risk factors associated with STIs.

METHODS

A total of 655 women aged 15-49 years were systematically enrolled from five health facilities using a cross-sectional study design. Cervical specimen were tested using GeneXpert CT/NG Assays for Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG), GeneXpertTV Assay for Trichomonas vaginalis (TV), and GeneXpert HPV Assays for hr-HPV. Blood samples were tested using Alere Determine HIV-1/2Ag/Ab Combo and Trinity Biotech Uni-Gold Recombigen HIV test for confirmation for HIV, and Rapid Plasma Reagin and TPHA test for confirmation for Treponema pallidum (syphilis). Genital warts were assessed prior to specimen collection. Survey weighted analyses were done to estimate the population burden of STIs.

RESULTS

The four most common curable STIs: CT, NG, TV, Treponema pallidum (syphilis), as well as genital warts were considered in this study. The overall weighted prevalence of any of these five STIs was 19.4% (95% CI: 14.9-24.8), corresponding to 72 990 women with STIs in Swaziland. The estimated prevalences were 7.0% (95% CI: 4.1-11.2) for CT, 6.0% (95% CI: 3.8-8.8) for NG, 8.4% (95% CI: 5.4-12.8) for TV, 1.4% (95% CI: 1.1-10.2) for syphilis and 2.0% (95% CI: 1.0-11.4) for genital warts. The overall weighted HIV prevalence was 42.7% (95%CI: 35.7-46.2). Among hr-HPV positive women, 18.8% (95% CI: 13.1-26.3) had one STI, while 6.3% (95% CI: 3.3-11.7) had multiple STIs. Risk factors associated with STIs were being employed (OR = 2.2, 95% CI: 1.0-4.7), self-employed (OR = 2.8, 95% CI: 1.5-5.5) and being hr-HPV positive (OR = 2.0, 95% CI: 1.3-3.1). Age (0.9, 95% CI: 0.8-0.9), being married (OR = 0.4, 95% CI: 0.3-0.7) and not using condoms with regular partners (OR = 0.5, 95% CI: 0.3-0.9) were inversely associated with STIs.

CONCLUSION

STIs are highly prevalent among women of reproductive age in Swaziland. Thus, a comprehensive STIs screening, surveillance and treatment programme would be justified and could potentially lower the burden of STIs in the country.

Integrated Polymerase Chain Reaction Technologies (Sample-to-Answer Technologies)

The tools available for both infectious disease diagnostics and human identity testing have benefitted from major technological advances in the automation of nucleic acid purification, amplification, and detection methods. The seamless integration of these processes into a fully automated microscale format has led to the development of rapid, user-friendly sample-to-answer assay systems. The application of these systems for human identity testing allows for DNA profiles to be generated in a field-forward environment where they can be used to generate investigative leads in crimes or other actionable intelligence. When used for infectious disease diagnostics, the sensitivity and specificity of these assay systems meets or exceeds that of more conventional strategies for the detection of respiratory, gastrointestinal, nervous system, and sexually transmitted pathogens. The anticipated medical benefits of this technology include shorter hospital stays, the elimination of unnecessary or ineffectual treatment, improved patient outcomes, and an overall quantifiable reduction in healthcare costs.

Molecular tests for the detection of antimicrobial resistant Neisseria gonorrhoeae: when, where, and how to use?

PURPOSE OF REVIEW

Molecular methods for the diagnosis of Neisseria gonorrhoeae are replacing bacterial culture in many settings. This review focuses on recent progress in the development of molecular tests to detect resistant N. gonorrhoeae both to enhance surveillance and to guide decisions about individual patient management.

RECENT FINDINGS

Assays to enhance surveillance have been developed to detect determinants of resistance for all antibiotics used as first-line gonorrhoea treatment, or to detect specific 'superbug' strains, but few have been applied in clinical practice. The most advanced strategy relevant to individual case management is to identify ciprofloxacin-sensitive strains so that unnecessary use of ceftriaxone can be avoided. Cross-reactivity with pharyngeal commensal Neisseria species reduces specificity and is a challenge for many assays.

SUMMARY

Progress with laboratory-based molecular tests to detect gonococcal resistance is being made but substantial challenges remain. No laboratory-based assay has been subjected to a field evaluation and no assay so far can be used as a point-of-care test. Given the threat of antimicrobial resistance, now is the time to exploit the molecular technologies used for diagnosis and to invest in the development of molecular gonococcal resistance tests that can be implemented for public health good.

Point-of-Care Diagnostics for Improving Maternal Health in South Africa

Improving maternal health is a global priority, particularly in high HIV-endemic, resource-limited settings. Failure to use health care facilities due to poor access is one of the main causes of maternal deaths in South Africa. "Point-of-care" (POC) diagnostics are an innovative healthcare approach to improve healthcare access and health outcomes in remote and resource-limited settings. In this review, POC testing is defined as a diagnostic test that is carried out near patients and leads to rapid clinical decisions. We review the current and emerging POC diagnostics for maternal health, with a specific focus on the World Health Organization (WHO) quality-ASSURED (Affordability, Sensitivity, Specificity, User friendly, Rapid and robust, Equipment free and Delivered) criteria for an ideal point-of-care test in resource-limited settings. The performance of POC diagnostics, barriers and challenges related to implementing POC diagnostics for maternal health in rural and resource-limited settings are reviewed. Innovative strategies for overcoming these barriers are recommended to achieve substantial progress on improving maternal health outcomes in these settings.

Prevalence of Chlamydia trachomatis and Neisseria gonorrhoeae infections detected by real-time PCR among individuals reporting sexual assaults in the Paris, France area

BACKGROUND

Neisseria gonorrhoeae (NG) and Chlamydia trachomatis (CT) are the most common bacteria involved in sexually transmitted infections (STIs). In France, combined screening for CT and NG using nucleic acid amplification tests is recommended in populations that are considered at risk. However, no data have been published about victims of sexual assaults. The aim of this retrospective study was to assess the usefulness of real-time PCR for the rapid detection of CT and NG genomic DNA, and the prevalence of CT/NG infections in a sample of sexual assault victims examined at a department of forensic medicine.

METHODS

Between July 2012 and July 2013, 326 adults and adolescents aged over 12 years reported a sexual assault and they were referred to the Department of Forensic Medicine for a medical and forensic examination. Secretions from urogenital (cervix or vagina), anorectal, or pharyngeal sites were collected for CT/NG assays.

RESULTS

CT and NG were detected in 48/326 (15%) and 16/326 patients (5%), respectively, where 10 (3%) had a CT/NG co-infection. Among 48 patients with CT infection, 13 (27.1%) patients had co-occurring genital and anorectal infections. For the pharyngeal sites, 3/21 men (14.3%) were NG-positive.

CONCLUSIONS

Given the high prevalence of CT and NG infections, systematic screening of both pathogens at the time of forensic examination should provide an opportunity for the early treatment of diagnosed STIs.

Evaluation of the Bio-Rad Dx CT/NG/MG® assay for simultaneous detection of Chlamydia trachomatis, Neisseria gonorrhoeae and Mycoplasma genitalium in urine

We evaluated the performance of the Bio-Rad real-time Dx CT/NG/MG® assay for detection of C. trachomatis, N. gonorrhoeae and M. genitalium on a collection of 441 urine samples from sexually transmitted infections, or travellers consultations and from anonymous sperm donors that were previously analysed with the Abbott RealTime CT/NG assay. Samples positive for C. trachomatis or N. gonorrhoeae with the Abbott assay had all previously been confirmed with an in-house real-time PCR assay. Samples positive for M. genitalium with the Bio-Rad assay were subsequently analysed by an in-house real-time PCR. On a total of 441 urines, 104 samples were positive for C. trachomatis, 12 were positive for N. gonorrhoeae and seven were positive for M. genitalium. After retesting of discrepant results, the test results were completely concordant, resulting in a calculated sensitivity and specificity of the Bio-Rad assay of 98.1 % and 100 % for C. trachomatis and of 91.7 % and 100 % for N. gonorrhoeae. Results for M. genitalium with the Bio-Rad assay were also concordant with the results of an in house PCR. We also evaluated the performance of automated nucleic acid extractions of urine samples with the NucliSENS easyMAG (bioMérieux) compared to the manual DNA extraction prescribed by the insert of the kit. The easyMAG extraction gave lower Ct values, relieved inhibition and had a lower hands-on time.

Acceptability and Feasibility of Sexually Transmitted Infection Testing and Treatment among Pregnant Women in Gaborone, Botswana, 2015

Introduction. Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG), and Trichomonas vaginalis (TV) are curable sexually transmitted infections (STIs) that can cause adverse maternal and birth outcomes. Most countries do not conduct routine testing during antenatal care. We present data on the acceptability and feasibility of testing and treating pregnant women for STIs in an antenatal clinic in Gaborone, Botswana. Materials and Methods. We offered CT, NG, and TV testing using self-collected vaginal swabs to eligible pregnant women. Participants received same-day test results. Those who tested positive were given treatment. Results. Among the 225 women who were eligible and recruited, 200 (89%) agreed to participate. The median age of our study sample was 30 years; most were unmarried (77%), with a median gestational age of 27 weeks and a 23% HIV prevalence. All participants received their results with at least 72% (n = 143) on the same day. Thirty participants (15%) tested positive for an STI, all were treated, and 24 (80%) were treated on the same day. Conclusion. The acceptability of STI testing was high, and the intervention was feasible. This study provides support for continued research into STI prevalence, cost-effectiveness, and the association of STIs with adverse maternal and infant outcomes.

Sample-to-result molecular infectious disease assays: clinical implications, limitations and potential

Molecular infectious disease diagnostic tests have undergone major advances in the past decade and will continue to rapidly evolve. Assays have become extraordinarily simple to perform, eliminating the need for pre-analytic sample preparation and post-amplification analysis. This allows these tests to be performed in settings without sophisticated expertise in molecular biology, including locations with limited resources. Additionally, the sensitivity and specificity of these assays is superb and many offer extremely fast turn-around times. These tests have major impacts on patient care, but also have some limitations.