This study highlights the development of a multiplex real-time loop-mediated isothermal amplification assay. The developed assay employed a dual-function oligonucleotide (DFO) which simultaneously monitors the emitted amplification signals and accelerates the amplification process. The DFO was a modification of loop primer (LP); the 5'-end and 3'-end of the LP was tagged with fluorophore and quencher, respectively. The DFO was quenched in its unbound state and fluoresces only when it anneals to the specific target during the amplification process. With the same working mechanism as LP, DFO allowed the detection of target genes in less than 1 h in a real time monitoring system. We demonstrated this detection platform with Burkholderia pseudomallei, the causative agent of melioidosis. An internal amplification control (IAC) was incorporated in the assay to rule out false negative result and to demonstrate that the assay was successfully developed in a multiplex system. The assay was 100% specific when it was evaluated against 96 B. pseudomallei clinical isolates and 48 other bacteria species. The detection limit (sensitivity) of the developed assay was 1 fg/μl of B. pseudomallei genomic DNA and 18.2 CFU/ml at the bacterial cell level. In spiked blood samples, the assay's detection limit was 14 CFU/ml. The assay's diagnostic evaluation showed 100% diagnostic sensitivity, diagnostic specificity, positive predictive value, and negative predictive value. An integrated multiplex LAMP and real-time monitoring system was successfully developed, simplifying the workflow for the rapid and specific nucleic acid diagnostic test.
Cholera, caused by Vibrio cholerae is a foodborne disease that frequently reported in food and water related outbreak. Rapid diagnosis of cholera infection is important to avoid potential spread of disease. Among available diagnostic platforms, loop-mediated isothermal amplification (LAMP) is regarded as a potential diagnostic tool due to its rapidity, high sensitivity and specificity and independent of sophisticated thermalcycler. However, the current LAMP often requires multiple pipetting steps, hence is susceptible to cross contamination. Besides, the strict requirement of cold-chain during transportation and storage make its application in low resource settings to be inconvenient. To overcome these problems, the present study is aimed to develop an ambient-temperature-stable and ready-to-use LAMP assay for the detection of toxigenic Vibrio cholerae in low resource settings. A set of specific LAMP primers were designed and tested against 155 V. cholerae and non-V. cholerae strains. Analytical specifity showed that the developed LAMP assay detected 100% of pathogenic V. cholerae and did not amplified other tested bacterial strains. Upon testing against stool samples spiked with toxigenic V. cholerae outbreak isolates, the LAMP assay detected all of the spiked samples (n = 76/76, 100%), in contrast to the conventional PCR which amplified 77.6% (n = 59/76) of the tested specimens. In term of sensitivity, the LAMP assay was 100-fold more sensitive as compared to the conventional PCR method, with LOD of 10 fg per μL and 10 CFU per mL. Following lyophilisation with addition of lyoprotectants, the dry-reagent LAMP mix has an estimated shelf-life of 90.75 days at room temperature.
Tumor-necrosis factor (TNF) is recognized as a therapeutic target in inflammatory diseases, including asthma. In severe forms of asthma, biologics such as anti-TNF are rendered to be investigated as therapeutic options in severe asthma. Hence, this work is done to assess the efficacy and safety of anti-TNF as a supplementary therapy for patients with severe asthma. A systematic search of 3 databases (Cochrane Central Register of Controlled Trials, MEDLINE, ClinicalTrials.gov) was performed to identify for published and unpublished randomized controlled trials comparing anti-TNF (etanercept, adalimumab, infliximab, certolizumab pegol, golimumab) with placebo in patients diagnosed with persistent or severe asthma. Random-effects model was used to estimate risk ratios and mean differences (MDs) with confidence intervals (95% CIs). PROSPERO registration number is CRD42020172006. Four trials with 489 randomized patients were included. Comparison between etanercept and placebo involved 3 trials while comparison between golimumab and placebo involved 1 trial. Etanercept produced a small but significant impairment in forced expiratory flow in 1 second (MD 0.33, 95% CI 0.09-0.57, I2 statistic = 0%, P = 0.008) and a modest improvement of asthma control using the Asthma Control Questionnaire. However, using the Asthma Quality of Life Questionnaire, the patients exhibit an impaired quality of life with etanercept. Treatment with etanercept showed a reduced injection site reaction and gastroenteritis compared with placebo. Although treatment with anti-TNF is shown to improve asthma control, severe asthma patients did not benefit from this therapy as there is limited evidence for improvement in lung function and reduction of asthma exacerbation. Hence, it is unlikely to prescribe anti-TNF in adults with severe asthma.