Prevalence and associated factors of sexually transmitted infections among methamphetamine users in Eastern China: a cross-sectional study

Background The reported incidence of sexually transmitted infections (STIs) in China has been increasing over the last decades, especially among drug users, which has become one of the main burdens of public health in China. This study was conducted to estimate the prevalence and associated factors of STIs among non-injecting methamphetamine (MA) users in Eastern China. Methods A cross-sectional survey was conducted among 632 MA users in Eastern China in 2017. Demographic characteristics, sexual behaviors, behaviors of MA use and sexual health knowledge were collected through questionnaire. First pass urine specimens were collected and detected for deoxyribonucleic acid (DNA) of Neisseria gonorrhoeae (NG) and Chlamydia trachomatis (CT) with Nucleic Acid Amplification Technology (NAAT), while blood specimens were collected and detected for antibodies of Human immunodeficiency virus (HIV), Herpes simplex virus type-2 (HSV-2), and syphilis with enzyme-linked immune sorbent assay (ELISA). Results Among the 632 MA users, 464 (73.42%) were males, 60.92% were < 35 years of age, 546 (86.39%) were Shandong residents. 317 (50.16%, 95% CI 46.26–54.06%) participants were tested positive for at least one kind of STIs, including 242 (38.29%, 95% CI 34.50–42.08%) for HSV-2, 107 (16.93%, 95% CI 14.01–19.85%) for active syphilis, 46 (7.28%, 95% CI 5.25–9.31%) for treated syphilis, 40 (6.33%, 95% CI 4.43–8.23%) for CT, 6 (0.95%, 95% CI 0.19–1.71%) for HIV, and 3 (0.47%, 95% CI 0.06–1.00%) for NG infection. 99 (15.66%, 95% CI 12.83–18.49%) participants were co-infected with two kinds of STIs, including 91 (14.40%, 95% CI 11.66–17.14%) participants were co-infected with HSV-2 and syphilis. 14 (2.22%, 95% CI 1.07–3.37%) participants were co-infected with three kinds of STIs, and 4 HIV positive participants were co-infected with both syphilis and HSV-2. In the multiple logistic regression analysis, the results showed that females (adjusted OR [AOR] = 7.30, 95% CI 4.34–12.30) and individuals ≥ 35 years of age (AOR = 2.97, 95% CI 2.04–4.32) were more likely to test positive for STIs among MA users, whereas participants who acquired sexual health knowledge primarily from the Internet (AOR = 0.57, 95% CI 0.40–0.82) and those whose regular partners did not use drugs (AOR = 0.59, 95% CI 0.37–0.94) were less likely. Conclusions This study found that the prevalence of HSV-2 and syphilis are alarming high among non-injecting MA users in Shandong Province in Eastern China. The prevention and control intervention of STIs among MA users in Shandong were needed, especially on females and MA users ≥ 35 years of age.

Analytical sensitivity and effectiveness of different SARS-CoV-2 testing options

We prepared severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) working standards and reference panels from a pool of swab fluid samples before and after inactivation by beta-propiolactone and quantified viral load in nucleic acid amplification technology (NAT) detectable RNA copies/mL using limiting dilution analysis. The following 50% lower limits of detection (LOD) were estimated by probit analysis as compared to detection limits of rapid antigen tests on 1.5 fold dilutions of the native material: Roche cobas PCR 1.8 (1.0-3.3), Hologic Aptima TMA 6.6 (4.4-9.9), DRW SAMBA 15 (7-30), Molgen LAMP 23 (13-42), Fluorecare antigen 50,000, Abbott Panbio antigen 75,000 and Roche antigen 100,000 copies/mL. One 50% Tissue Culture Infectious Dose (TCID50)/mL of culture fluid was estimated to be equivalent to approximately 1000 RNA copies/mL (2700- 4300 International Units) in our working standard. When assuming this level as start of contagiousness in a log-linear ramp up viremia model with 10-fold rise of viral load per day for the B.1 (Wuhan) type we estimated relative time points of first detectability of early infection by the different SARS-CoV-2 assays from the LODs mentioned above. The four NAT assays would be able to detect early viremia 40-66 hours earlier than the 1000 copies/mL infectivity threshold, whereas the three antigen tests would become positive 41-48 hours later. Our modeling of analytical sensitivity data was found to be compatible with clinical sensitivity data of rapid antigen tests and confirms that NAT assays are more reliable than antigen assays for identifying early infected asymptomatic individuals who are potentially infectious.

Pulse-Controlled Amplification–A new powerful tool for on-site diagnostics under resource limited conditions

Background Molecular diagnostics has become essential in the identification of many infectious and neglected diseases, and the detection of nucleic acids often serves as the gold standard technique for most infectious agents. However, established techniques like polymerase chain reaction (PCR) are time-consuming laboratory-bound techniques while rapid tests such as Lateral Flow Immunochromatographic tests often lack the required sensitivity and/or specificity. Methods/Principle findings Here we present an affordable, highly mobile alternative method for the rapid identification of infectious agents using pulse-controlled amplification (PCA). PCA is a next generation nucleic acid amplification technology that uses rapid energy pulses to heat microcyclers (micro-scale metal heating elements embedded directly in the amplification reaction) for a few microseconds, thus only heating a small fraction of the reaction volume. The heated microcyclers cool off nearly instantaneously, resulting in ultra-fast heating and cooling cycles during which classic amplification of a target sequence takes place. This reduces the overall amplification time by a factor of up to 10, enabling a sample-to-result workflow in just 15 minutes, while running on a small and portable prototype device. In this proof of principle study, we designed a PCA-assay for the detection of Yersinia pestis to demonstrate the efficacy of this technology. The observed detection limits were 434 copies per reaction (purified DNA) and 35 cells per reaction (crude sample) respectively of Yersinia pestis. Conclusions/Significance PCA offers fast and decentralized molecular diagnostics and is applicable whenever rapid, on-site detection of infectious agents is needed, even under resource limited conditions. It combines the sensitivity and specificity of PCR with the rapidness and simplicity of hitherto existing rapid tests.

Rapid Detection of Hepatitis B Virus in Blood Samples Using a Combination of Polymerase Spiral Reaction With Nanoparticles Lateral-Flow Biosensor

A rapid, highly sensitive, and robust diagnostic technique for point-of-care (PoC) testing can be developed using the combination of the nanoparticle-based lateral flow biosensors (LFB) and isothermal nucleic acid amplification technology. Here, we developed a polymerase spiral reaction (PSR) containing FITC-labeled DNA probes coupled with the nanoparticle-based LFB assay (PSR-LFB) to detect the amplified products to detect HBV visually. Under the optimized conditions, the PSR assay involved incubation of the reaction mixture for 20 min at 63°C, followed by visual detection of positive amplicons using LFB, which would generate a red test line based on the biotin/streptavidin interaction and immunoreactions, within 5 min. A cross-reactivity test revealed that the developed PSR-LFB assay showed good specificity for HBV and could distinguish HBV from other pathogenic microorganisms. For the analytical sensitivity, the limit of detection (LoD) of PSR-LFB assay was recorded as 5.4 copies/mL of HBV genomic DNA, which was ten-times more sensitive than qPCR and loop-mediated isothermal amplification (LAMP). Additionally, all the HBV-positive (29/82) samples, identified using ELISA, were also successfully detected by the PSR-LFB assay. We found that the true positive rate of the PSR-LFB assay was higher than that of qPCR (100 vs. 89.66%, respectively), as well as the LAMP assay (100 vs. 96.55%, respectively). Furthermore, the integrated procedure could be completed in 60 min, including the processing of the blood samples (30 min), an isothermal reaction (20 min), and result visualization (5 min). Thus, this PSR-LFB assay could be a potentially useful technique for PoC diagnosis of HBV in resource-limited countries.

Traditional and new applications of HCR in biosensing and biomedicine

Hybridization chain reaction is a very popular isothermal nucleic acid amplification technology. A single-stranded DNA initiator triggers an alternate hybridization event between two hairpins forming a double helix polymer. Due...

Detection of Epstein–Barr virus by a rapid and simple accelerated denaturation bubble-mediated strand exchange amplification method

A rapid and simple nucleic acid amplification technology for EBV detection.

Leapfrogging laboratories: the promise and pitfalls of high-tech solutions for antimicrobial resistance surveillance in low-income settings

The scope and trajectory of today’s escalating antimicrobial resistance (AMR) crisis is inadequately captured by existing surveillance systems, particularly those of lower income settings. AMR surveillance systems typically collate data from routine culture and susceptibility testing performed in diagnostic bacteriology laboratories to support healthcare. Limited access to high quality culture and susceptibility testing results in the dearth of AMR surveillance data, typical of many parts of the world where the infectious disease burden and antimicrobial need are high. Culture and susceptibility testing by traditional techniques is also slow, which limits its value in infection management. Here, we outline hurdles to effective resistance surveillance in many low-income settings and encourage an open attitude towards new and evolving technologies that, if adopted, could close resistance surveillance gaps. Emerging advancements in point-of-care testing, laboratory detection of resistance through or without culture, and in data handling, have the potential to generate resistance data from previously unrepresented locales while simultaneously supporting healthcare. Among them are microfluidic, nucleic acid amplification technology and next-generation sequencing approaches. Other low tech or as yet unidentified innovations could also rapidly accelerate AMR surveillance. Parallel advances in data handling further promise to significantly improve AMR surveillance, and new frameworks that can capture, collate and use alternate data formats may need to be developed. We outline the promise and limitations of such technologies, their potential to leapfrog surveillance over currently available, conventional technologies in use today and early steps that health systems could take towards preparing to adopt them.

Using gel-electrophoresis and traditional PCR in RT-PCR assays for the detection of SARS-CoV-2 in resource limited areas

Background. qRT-PCR investigations on patient specimen seem to be the only probable laboratory technology to validate the current individual SARS-CoV-2 status correctly. This kind of nucleic acid amplification technology is available in most countries, but missing in resource limited areas with poor laboratory infrastructure. The most feasible way to build up PCR test capacities for SARS-CoV-2 in these areas is the use of conventional PCR. PCR-thermocycler and gel-electrophoresis systems could be shipped easily by parcel service to the whole world, because they are almost maintenance free and need no engineers for their installation and service. Methods. In order to reduce the complexity of sensitive reagent kits we have developed a freeze dried test kit for the traditional RT-PCR for the detection of SARS-CoV-2 in single ready to use tubes. Transport and storage of the reagents are now free of any cooling chain.Results. We have analysed 244 patient samples and compared the results to the SEEGENE Allplex™ 2019-nCoV assay. The sensitivity and specificity were 95.5% and 98.5%, respectively. Next to these performance parameters we could implement a workflow for processing 96 patient samples in parallel, handled by only 1 laboratory technician in an 8 hours working day.Conclusion. The use of conventional PCR in combination with gel-electrophoresis for test analysis is a feasible approach to make SARS-CoV-2 diagnostic available in the whole world. This is needed urgently, because SARS-CoV-2 is a question of global health and not only of the well-equipped countries.