Novel lateral flow assay for point-of-care detection of Neisseria gonorrhoeae infection in syndromic management settings: a cross-sectional performance evaluation

Spectrum of sexual partner types among adults screened for sexually transmitted infections in the Eastern Cape, South Africa

In South Africa, Chlamydia trachomatis prevalence is 14.7% in women and 6.6% in men, while Neisseria gonorrhoeae rates are 6.0% and 3.4%. Partner management, including identifying and screening for STIs, is essential for STI control efforts but challenging due to relationship dynamics, fear of disclosure and stigma. This study aims to understand how adults in the Eastern Cape report partner types when seeking STI care, enhancing partner notification strategies and reducing transmission. From February-August 2023, a cross-sectional evaluation of a Neisseria gonorrhoeae lateral flow assay was conducted among asymptomatic adults aged 18-49 years at four primary healthcare facilities in Buffalo City, Eastern Cape. Participants completed surveys classifying partners into LUSTRUM team's 8 partner types and 5 type-classifications. Data were analyzed using StataSE 17, examining associations between partner types and variables like gender, location, number of sexual partners, and STI test results. A total of 500 men and 400 women (median ages 31 and 32) were recruited. The most reported partner types were main/serious/long-term partners (41%) and girlfriend/boyfriend (29%) or LUSTRUM's 4: established (67%) and occasional partners (28%). Participants reporting main/long-term partners, steady, or boyfriend/girlfriend showed variability in partner numbers. Male adults more commonly reported casual partner types like friends with benefits (21% vs. 9%) and fuck buddy/booty call (9% vs. 3%), with significant associations for super casual/hook-up/meet/one-night stand (p = 0.02). Regional differences in partner types and a significant association between new partners and NG Xpert positivity (p = 0.01) were observed. This study confirms the diverse spectrum of sexual partner types. Findings reveal that men and women may have different relationships, and regional variations suggest context-specific approaches are needed. Identifying partner types can enhance communication and treatment strategies and address significant gaps in partner notification and STI care.

Urobiome and Inflammation: A Systematic Review on Microbial Imbalances and Diagnostic Tools for Urinary Disorders

OBJECTIVE

To synthesize current knowledge on urobiome alterations, innovative diagnostic advancements, and emerging therapeutic strategies targeting urobiome dysbiosis in inflammatory urinary tract disorders, including urinary tract infections, nongonococcal urethritis, and interstitial cystitis.

METHODS

A systematic review was conducted by screening the most important scientific databases. The search included the keywords: (microbiome) OR (microbial) OR (bacteria) OR (bacterial profile) AND (urine) OR (urinary) AND (first-morning sample) OR (first void). Only original studies in English involving human specimens were considered.

RESULTS

Of the 760 articles initially identified, a final sample of 20 original studies met the inclusion criteria. Disruptions in the urobiome composition were associated with increased colonization by pathogens such as Escherichia coli and Mycoplasma genitalium, resulting in inflammation and recurrent urinary conditions. Advanced diagnostic techniques, including metaproteomics, metagenomics, and point-of-care assays such as Neisseria gonorrhoeae lateral flow assay, demonstrated enhanced capabilities for rapid pathogen detection and differentiation of inflammatory conditions. Therapeutic interventions targeting urobiome dysbiosis, particularly probiotics (Lactobacillus rhamnosus, L. reuteri, L. crispatus), showed promising efficacy in reducing recurrence and inflammation in clinical trials.

CONCLUSION

Urobiome dysbiosis plays a critical role in inflammatory urinary tract disorders. Innovative diagnostic methods and targeted therapeutic approaches, especially probiotics, offer substantial potential to improve patient outcomes. Further research is warranted to refine these strategies and validate their clinical applicability.

Increasing Access To Sexually Transmitted Infection Testing: The Promise of Point-of-Care and Over-the-Counter Tests

PURPOSE OF REVIEW

Rapid, simple, inexpensive tests that can be used to detect sexually transmitted infections (STI) in symptomatic patients and for asymptomatic screening, especially in women, is a global critical unmet need in all income settings. We sought to review the STI diagnostic unmet need and current landscape of diagnostic tests that are either approved or in development.

RECENT FINDINGS

Diagnostic certainty will be required to decrease the global burden of STI's particularly in low-resource settings where empiric algorithmic care predominates. Lateral flow assays for syphilis and HIV have been successfully used in low- and middle-income countries. Although the performance of reference lab nucleic acid amplification tests is excellent for the detection of Neisseria gonorrhoeae and Chlamydia trachomatis, such tests remain expensive and globally unavailable due to lack of existing clinical lab infrastructure. Importantly, diagnostic innovations from the COVID-19 pandemic are being leveraged for developing molecular STI point-of-care tests and over-the-counter (OTC) self-tests. In the US and other high-income countries, point-of-care testing of both symptomatic and asymptomatic people would allow for a definitive STI diagnosis, appropriate treatment within a clinical encounter, and decreased antibiotic overuse, a significant global public health problem. Most exciting is the possibility for rapid, high performance self-tests. Inexpensive and rapid STI self-test could significantly increase access to STI care and help decrease health inequity.

Recent advances in centrifugal microfluidics for point-of-care testing

Point-of-care testing (POCT) holds significant importance in the field of infectious disease prevention and control, as well as personalized precision medicine. The emerging microfluidics, capable of minimal reagent consumption, integration, and a high degree of automation, play a pivotal role in POCT. Centrifugal microfluidics, also termed lab-on-a-disc (LOAD), is a significant subfield of microfluidics that integrates crucial analytical steps onto a single chip, thereby optimizing the process and enabling high-throughput, automated analysis. By utilizing rotational mechanics to precisely control fluid dynamics without external pressure sources, centrifugal microfluidics facilitates swift operations ideal for urgent medical and field settings. This review provides a comprehensive overview of the latest advancements in centrifugal microfluidics for POCT, covering both theoretical principles and practical applications. We begin by introducing the fundamental operational principles, fluidic control mechanisms, and signal output detection methods. Subsequently, we delve into the typical applications of centrifugal microfluidic platforms in immunoassays, nucleic acid testing, antimicrobial susceptibility testing, and other tests. We also discuss the strengths and potential limitations of centrifugal microfluidic platforms, underscoring their transformative impact on traditional conventional procedures and their significant role in diagnostic practices.

Preliminary clinical performance of a Cas13a-based lateral flow assay for detecting Neisseria gonorrhoeae in urine specimens

Nucleic acid amplification testing (NAAT) for N. gonorrhoeae is unavailable in resource-limited settings. We previously developed a CRISPR-based lateral flow assay for detecting N. gonorrhoeae. We aimed to pair that assay with point-of-care DNA extraction, assess performance in clinical urine specimens, and optimize assay kinetics. We collected urine specimens among men presenting with urethritis enrolling in a clinical trial at the Massachusetts General Hospital Sexual Health Clinic. We assessed the quantified DNA yield of detergent-based extractions with and without heat. We selected one detergent for extracting all specimens, paired with isothermal recombinase polymerase amplification for 90 minutes and lateral flow Cas13a detection, interpreted via pixel intensity analysis. We also trained a smartphone-based machine-learning model on 1,008 images to classify lateral flow results. We used the model to interpret lateral flow results from the clinical specimens. We also tested a modified amplification chemistry with a second forward primer lacking the T7-promoter to accelerate reaction kinetics. Extraction with 0.02% Triton X resulted in an average DNA yield of 2.6 × 106 copies/µL (SD ± 6.7 × 105). We treated 40 urine specimens (n = 12 positive) with 0.02% Triton X, and using quantified pixel intensity analysis, the Cas13a-based assay correctly classified all specimens (100% agreement; 95% CI 91.2%-100%). The machine-learning model correctly classified 45/45 strips in the validation data set and all 40 lateral flow strips from clinical specimens. Including the second forward primer reduced incubation time to 60 minutes. Using point-of-care DNA extraction, our Cas13a-based lateral flow N. gonorrhoeae assay demonstrated promising performance among clinical urine specimens.IMPORTANCEUsing a CRISPR-based assay we previously developed for Neisseria gonorrhoeae detection, we developed new techniques to facilitate point-of-care use. We then demonstrated the promising performance of that assay in clinical specimens. Furthermore, we developed a smartphone-based machine learning application for assisting interpretation of lateral flow strip results. Such an assay has the potential to transform the care of sexually transmitted infections in low-resource settings where diagnostic tests are unavailable. A point-of-care pathogen-specific assay, paired with the connectivity offered by a smartphone application, can also support public health surveillance efforts in such areas.

Role of HIV self-testing in strengthening HIV prevention services

HIV self-testing, which has been increasingly available since 2016, can substantially enhance the uptake of HIV testing, especially for key populations. Clinical trials have explored the application of self-testing in various HIV prevention strategies, including post-exposure prophylaxis (PEP), pre-exposure prophylaxis (PrEP), and voluntary medical male circumcision. Research indicates that self-testing can facilitate PrEP initiation and improve adherence and continuation. However, evidence on the effectiveness of linkage to PrEP post HIV self-testing is mixed, underscoring the need to further understand contextual factors and optimal implementation strategies. Studies on linking voluntary medical male circumcision post HIV self-testing show no statistically significant difference compared with standard voluntary medical male circumcision demand creation strategies. There is a shortage of trials examining the role of self-testing in PrEP reinitiation, PEP initiation, or PEP follow-up. Evidence for the use of HIV prevention models that support self-testing is accumulating, but there is a need for further research in different contexts and among different populations to assess its value when scaled up to contribute to reducing HIV infections globally.

Expanding antibiotic, vaccine, and diagnostics development and access to tackle antimicrobial resistance

The increasing number of bacterial infections globally that do not respond to any available antibiotics indicates a need to invest in-and ensure access to-new antibiotics, vaccines, and diagnostics. The traditional model of drug development, which depends on substantial revenues to motivate investment, is no longer economically viable without push and pull incentives. Moreover, drugs developed through these mechanisms are unlikely to be affordable for all patients in need, particularly in low-income and middle-income countries. New, publicly funded models based on public-private partnerships could support investment in antibiotics and novel alternatives, and lower patients' out-of-pocket costs, making drugs more accessible. Cost reductions can be achieved with public goods, such as clinical trial networks and platform-based quality assurance, manufacturing, and product development support. Preserving antibiotic effectiveness relies on accurate and timely diagnosis; however scaling up diagnostics faces technological, economic, and behavioural challenges. New technologies appeared during the COVID-19 pandemic, but there is a need for a deeper understanding of market, physician, and consumer behaviour to improve the use of diagnostics in patient management. Ensuring sustainable access to antibiotics also requires infection prevention. Vaccines offer the potential to prevent infections from drug-resistant pathogens, but funding for vaccine development has been scarce in this context. The High-Level Meeting of the UN General Assembly in 2024 offers an opportunity to rethink how research and development can be reoriented to serve disease management, prevention, patient access, and antibiotic stewardship.

Kanoi B, Kimani R, Maina M, Waweru H, Kamita M, Ndirangu I, M. Abkallo H, Oduor B, Pamme N, Dupaty J, M. Klapperich C, Raju Lolabattu S, Gitaka J. Multi-repeat sequences identification using genome mining techniques for developing highly sensitive molecular diagnostic assay for the detection of Chlamydia trachomatis

Chlamydia trachomatis ( C. trachomatis) is a common sexually transmitted infection (STI). In 2019, the World Health Organization reported about 131 million infections. The majority of infected patients are asymptomatic with cases remaining undetected. It is likely that missed C. trachomatis infections contribute to preventable adverse health outcomes in women and children. Consequently, there is an urgent need of developing efficient diagnostic methods. In this study, genome-mining approaches to identify identical multi-repeat sequences (IMRS) distributed throughout the C. trachomatis genome were used to design a primer pair that would target regions in the genome. Genomic DNA was 10-fold serially diluted (100pg/μL to 1×10 -3pg/μL) and used as DNA template for PCR reactions. The gold standard PCR using 16S rRNA primers was also run as a comparative test, and products were resolved on agarose gel. The novel assay, C. trachomatis IMRS-PCR, had an analytical sensitivity of 4.31 pg/µL, representing better sensitivity compared with 16S rRNA PCR (9.5 fg/µL). Our experimental data demonstrate the successful development of lateral flow and isothermal assays for detecting C. trachomatis DNA with potential use in field settings. There is a potential to implement this concept in miniaturized, isothermal, microfluidic platforms, and laboratory-on-a-chip diagnostic devices for reliable point-of-care testing.

Clinical Performance of Cas13a-based Point-of-Care Lateral Flow Assay for Detecting Neisseria gonorrhoeae

Background

Diagnosis of Neisseria (N.) gonorrhoeae is dependent on nucleic acid amplification testing (NAAT), which is not available in resource-limited settings where the prevalence of infection is highest. Recent advances in molecular diagnostics leveraging the high specificity of CRISPR enzymes can permit field-deployable, point-of-care lateral flow assays. We previously reported on the development and in vitro performance of a lateral flow assay for detecting N. gonorrhoeae. Here we aimed to pair that assay with point-of-care DNA extraction techniques and assess the performance on clinical urine specimens.

Methods

We collected an additional urine specimen among individuals enrolling in an ongoing clinical trial at the Massachusetts General Hospital Sexual Health Clinic who presented with symptoms of urethritis or cervicitis (urethral or vaginal discharge, dysuria, or dyspareunia). We then assessed thermal, detergent, and combination DNA extraction conditions, varying the duration of heat at 95°C and concentration of Triton X. We assessed the efficacy of the various DNA extraction methods by quantitative polymerase chain reaction (qPCR). Once an extraction method was selected, we incubated samples for 90 minutes to permit isothermal recombinase polymerase amplification. We then assessed the performance of lateral flow Cas13a-based detection using our previously designed porA probe and primer system for N. gonorrhoeae detection, comparing lateral flow results with NAAT results from clinical care.

Results

We assessed DNA extraction conditions on 3 clinical urine specimens. There was no consistent significant difference in copies per microliter of DNA obtained using more or less heat. On average, we noted that 0.02% triton combined with 5 minutes of heating to 95°C resulted in the highest DNA yield, however, 0.02% triton alone resulted in a quantity of DNA that was above the previously determined analytic sensitivity of the assay. Given that detergent-based extraction is more easily deployable, we selected that as our method for extraction. We treated 23 clinical specimens with 0.02% triton, which we added to the Cas13a detection system. We ran all lateral flow detections in duplicate. The Cas13a-based assay detected 8 of 8 (100%) positive specimens, and 0 of 15 negative specimens.

Conclusion

Using point-of-care DNA extraction, isothermal amplification, and Cas13a-based detection, our point-of-care lateral flow N. gonorrhoeae assay correctly identified 23 clinical urine specimens as either positive or negative. Further evaluation of this assay among larger samples and more diverse sample types is warranted.