Visual and rapid identification of Chlamydia trachomatis and Neisseria gonorrhoeae using multiplex loop-mediated isothermal amplification and a gold nanoparticle-based lateral flow biosensor

Gold nanoparticles-based biosensors: pioneering solutions for bacterial and viral pathogen detection-a comprehensive review

Gold Nanoparticles (AuNPs) have gained significant attention in biosensor development due to their unique physical, chemical, and optical properties. When incorporated into biosensors, AuNPs offer several advantages, including a high surface area-to-volume ratio, excellent biocompatibility, ease of functionalization, and tunable optical properties. These properties make them ideal for the detection of various biomolecules, including proteins, nucleic acids, and bacterial and viral biomarkers. Traditional methods for detecting bacteria and viruses, such as RT-PCR and ELISA, often suffer from complexities, time consumption, and labor intensiveness. Consequently, researchers are continuously exploring novel devices to address these limitations and effectively detect a diverse array of infectious pathogenic microorganisms. In light of these challenges, nanotechnology has been instrumental in refining the architecture and performance of biosensors. By leveraging advancements in nanomaterials and strategies of biosensor fabrication the sensitivity and specificity of biosensors can be enhanced, enabling more precise detection of pathogenic bacteria and viruses. This review explores the versatility of AuNPs in detecting a variety of biomolecules, including proteins, nucleic acids, and bacterial and viral biomarkers. Furthermore, it evaluates recent advancements in AuNPs-based biosensors for the detection of pathogens, utilizing techniques such as optical biosensors, lateral flow immunoassays, colorimetric immunosensors, electrochemical biosensors, and fluorescence nanobiosensors. Additionally, the study discusses the existing challenges in the field and proposes future directions to improve AuNPs-based biosensors, with a focus on enhancing sensitivity, selectivity, and their utility in clinical and diagnostic applications.

Rethinking the application of nanoparticles in women's reproductive health and assisted reproduction

Nanoparticles and nanotechnology may present opportunities to revolutionize the prevention, treatment and diagnosis of a range of reproductive health conditions in women. These technologies are also used to improve outcomes of assisted reproductive technology. We highlight a range of these potential clinical uses of nanoparticles for polycystic ovary syndrome, endometriosis, uterine fibroids and sexually transmitted infections, considering in vitro and in vivo studies along with clinical trials. In addition, we discuss applications of nanoparticles in assisted reproductive technology, including sperm loading, gamete and embryo preservation and preventing preterm birth. Finally, we present some of the concerns associated with the medical use of nanoparticles, identifying routes for further exploration before nanoparticles can be applied to women's reproductive health in the clinic.

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.

Validation of a New Duplex Real-Time Polymerase Chain Reaction for Chlamydia trachomatis DNA Detection in Ocular Swab Samples

Trachoma is the world-leading infectious cause of preventable blindness and is caused by the bacteria Chlamydia trachomatis. In developing countries, diagnosis is usually based on clinical evaluation. Serological-based tests are cheaper than molecular-based ones, but the latter are more sensitive and specific. The present study developed a new duplex qPCR which concomitantly detects the C. trachomatis cryptic plasmid and the human 18S rRNA gene, with an LOD95% for C. trachomatis DNA of 13.04 genome equivalents per reaction. The new qPCR was tested using 50 samples from an endemic area and 12 from a non-endemic area that were previously characterized using direct immunofluorescence assay (DFA) and clinical evaluation. Among the 50 endemic samples, 3 were found to be positive by clinical evaluation (6%), 18 were found to be positive by DFA (36%), and 48 were found to be positive by qPCR (96%). Next, the new duplex qPCR was validated using 50 samples previously characterized by qPCR. Validation was carried out on a benchtop instrument (ABI7500) or on a portable point-of-care instrument (Q3-Plus), showing 95% specificity and 100% sensitivity. The ubiquitous presence of C. trachomatis DNA in samples from the endemic region confirms that constant monitoring is of paramount importance for the effective measurement of the elimination of trachoma. The newly developed duplex qPCR presented in this study, along with its validation in a portable qPCR system, constitutes important tools toward achieving this goal.

Moving towards on-site detection of Shiga toxin-producing Escherichia coli in ready-to-eat leafy greens

Rapid identification of Shiga toxin-producing Escherichia coli, or STEC, is of utmost importance to assure the innocuousness of the foodstuffs. STEC have been implicated in outbreaks associated with different types of foods however, among them, ready-to-eat (RTE) vegetables are particularly problematic as they are consumed raw, and are rich in compounds that inhibit DNA-based detection methods such as qPCR. In the present study a novel method based on Loop-mediated isothermal amplification (LAMP) to overcome the limitations associated with current molecular methods for the detection of STEC in RTE vegetables targeting stx1 and stx2 genes. In this sense, LAMP demonstrated to be more robust against inhibitory substances in food. In this study, a comprehensive enrichment protocol was combined with four inexpensive DNA extraction protocols. The one based on silica purification enhanced the performance of the method, therefore it was selected for its implementation in the final method. Additionally, three different detection chemistries were compared, namely real-time fluorescence detection, and two end-point colorimetric strategies, one based on the addition of SYBR Green, and the other based on a commercial colorimetric master mix. After optimization, all three chemistries demonstrated suitable for the detection of STEC in spiked RTE salad samples, as it was possible to reach a LOD50 of 0.9, 1.4, and 7.0 CFU/25 g for the real-time, SYBR and CC LAMP assays respectively. All the performance parameters reached values higher than 90 %, when compared to a reference method based on multiplex qPCR. More specifically, the analytical sensitivity was 100, 90.0 and 100 % for real-time, SYBR and CC LAMP respectively, the specificity 100 % for all three assays, and accuracy 100, 96 and 100 %. Finally, a high degree of concordance was also obtained (1, 0.92 and 1 respectively). Considering the current technological advances, the method reported, using any of the three detection strategies, demonstrated suitable for their implementation in decentralized settings, with low equipment resources.

Membrane computing simulation of sexually transmitted bacterial infections in hotspots of individuals with various risk behaviors

The epidemiology of sexually transmitted infections (STIs) is complex due to the coexistence of various pathogens, the variety of transmission modes derived from sexual orientations and behaviors at different ages and genders, and sexual contact hotspots resulting in network transmission. There is also a growing proportion of recreational drug users engaged in high-risk sexual activities, as well as pharmacological self-protection routines fostering non-condom practices. The frequency of asymptomatic patients makes it difficult to develop a comprehensive approach to STI epidemiology. Modeling approaches are required to deal with such complexity. Membrane computing is a natural computing methodology for the virtual reproduction of epidemics under the influence of deterministic and stochastic events with an unprecedented level of granularity. The application of the LOIMOS program to STI epidemiology illustrates the possibility of using it to shape appropriate interventions. Under the conditions of our basic landscape, including sexual hotspots of individuals with various risk behaviors, an increase in condom use reduces STIs in a larger proportion of heterosexuals than in same-gender sexual contacts and is much more efficient for reducing Neisseria gonorrhoeae than Chlamydia and lymphogranuloma venereum infections. Amelioration from diagnostic STI screening could be instrumental in reducing N. gonorrhoeae infections, particularly in men having sex with men (MSM), and Chlamydia trachomatis infections in the heterosexual population; however, screening was less effective in decreasing lymphogranuloma venereum infections in MSM. The influence of STI epidemiology of sexual contacts between different age groups (<35 and ≥35 years) and in bisexual populations was also submitted for simulation.IMPORTANCEThe epidemiology of sexually transmitted infections (STIs) is complex and significantly influences sexual and reproductive health worldwide. Gender, age, sexual orientation, sexual behavior (including recreational drug use and physical and pharmacological protection practices), the structure of sexual contact networks, and the limited application or efficiency of diagnostic screening procedures create variable landscapes in different countries. Modeling techniques are required to deal with such complexity. We propose the use of a simulation technology based on membrane computing, mimicking in silico STI epidemics under various local conditions with an unprecedented level of detail. This approach allows us to evaluate the relative weight of the various epidemic drivers in various populations at risk and the possible outcomes of interventions in particular epidemiological landscapes.

Handheld Ultra-Fast Duplex Polymerase Chain Reaction Assays and Lateral Flow Detection and Identification of Leishmania Parasites for Cutaneous Leishmaniases Diagnosis

Early and accurate detection of infectious diseases is a key step for surveillance, epidemiology and control, notably timely disease diagnosis, patient management and follow-up. In this study, we aimed to develop handheld ultra-fast duplex PCR assays coupled to amplicon detection by lateral flow (LF) immunoassay to deliver a rapid and simple molecular diagnostic test for concomitant detection and identification of the main Leishmania parasites encountered in Tunisia. We selected two DNA targets to amplify L. major/L. tropica and L. infantum/L. tropica groups of species DNAs, respectively. We optimized the experimental conditions of a duplex ultra-fast PCR. The amplification is performed using a portable Palm convection PCR machine within 18 min, and the products are detected using an LF cassette within 10 min. The test allows the identification of the infecting species according to the position and number of test lines revealed. Tested on a selection of DNAs of representative Leishmania strains of the three studied species (N = 37), the ultra-fast duplex PCR-LF showed consistent, stable and reproducible results. The analytical limit of detection of the test was 0.4 pg for L. major, 4 pg for L. infantum and 40 pg for L. tropica.