scholarly journals Advanced Multiplex Loop Mediated Isothermal Amplification (mLAMP) Combined with Lateral Flow Detection (LFD) for Rapid Detection of Two Prevalent Malaria Species in India and Melting Curve Analysis

Diagnostics ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 32
Author(s):  
Supriya Sharma ◽  
Sandeep Kumar ◽  
Md.Zohaib Ahmed ◽  
Nitin Bhardwaj ◽  
Jaskirat Singh ◽  
...  
Keyword(s):  
Point Of Care ◽  
Melting Curve ◽  
Lateral Flow ◽  
Curve Analysis ◽  
Isothermal Amplification ◽  
Clinical Samples ◽  
Melting Curve Analysis ◽  
Loop Mediated Isothermal Amplification ◽  
Malaria Species ◽  
Flow Detection

Isothermal techniques with lateral flow detection have emerged as a point of care (POC) technique for malaria, a major parasitic disease in tropical countries such as India. Plasmodium falciparum and Plasmodium vivax are the two most prevalent malaria species found in the country. An advanced multiplex loop-mediated isothermal amplification (mLAMP) combined with a lateral flow dipstick (LFD) technique was developed for the swift and accurate detection of P. falciparum and P. vivax, overcoming the challenges of the existing RDTs (rapid diagnostic tests). A single set of LAMP primers with a biotinylated backward inner primer (BIP primer) was used for DNA amplification of both malaria species in a single tube. The amplified DNA was hybridized with fluorescein isothiocyanate (FITC) and digoxigenin-labelled DNA probes, having a complemented sequence for the P. falciparum and P. vivax genomes, respectively. A colour band appeared on two separate LFDs for P. falciparum and P. vivax upon running the hybridized solution over them. In total, 39 clinical samples were collected from ICMR-NIMR, New Delhi. Melting curve analysis, with cross primers for both species, was used to ascertain specificity, and the sensitivity was equated with a polymerase chain reaction (PCR). The results were visualized on the LFD for both species within 60 min. We found 100% sensitivity and specificity, when compared with a traditional PCR. Melting curve analysis of mLAMP revealed the lowest detection limit of 0.15 pg/μL from sample genomic DNA. The mLAMP-LFD assays could be a potential point of care (POC) tool for early diagnosis in non-laboratory conditions, with the convenience of a reduced assay time and the simple interpretation of results.

scholarly journals Essential properties and pitfalls of colorimetric Reverse Transcription Loop-mediated Isothermal Amplification as a point-of-care test for SARS-CoV-2 diagnosis

2021 ◽  
Vol 27 (1) ◽  
Author(s):  
Bruna de Oliveira Coelho ◽  
Heloisa Bruna Soligo Sanchuki ◽  
Dalila Luciola Zanette ◽  
Jeanine Marie Nardin ◽  
Hugo Manuel Paz Morales ◽  
...  
Keyword(s):  
Viral Load ◽  
Internal Control ◽  
Reverse Transcription ◽  
Color Change ◽  
Point Of Care ◽  
Colorimetric Detection ◽  
False Negative ◽  
Isothermal Amplification ◽  
Clinical Samples ◽  
Loop Mediated Isothermal Amplification

Abstract Background SARS-CoV-2 Reverse Transcription Loop-mediated Isothermal Amplification (RT-LAMP) colorimetric detection is a sensitive and specific point-of-care molecular biology technique used to detect the virus in only 30 min. In this manuscript we have described a few nuances of the technique still not properly described in the literature: the presence of three colors clusters; the correlation of the viral load with the color change; and the importance of using an internal control to avoid false-negative results. Methods To achieve these findings, we performed colorimetric RT-LAMP assays of 466 SARS-CoV-2 RT-qPCR validated clinical samples, with color quantification measured at 434 nm and 560 nm. Results First we determinate a sensitivity of 93.8% and specificity of 90.4%. In addition to the pink (negative) and yellow (positive) produced colors, we report for the first time the presence of an orange color cluster that may lead to wrong diagnosis. We also demonstrated using RT-qPCR and RT-LAMP that low viral loads are related to Ct values > 30, resulting in orange colors. We also demonstrated that the diagnosis of COVID-19 by colorimetric RT-LAMP is efficient until the fifth symptoms day when the viral load is still relatively high. Conclusion This study reports properties and indications for colorimetric RT-LAMP as point-of-care for SARS-CoV-2 diagnostic, reducing false results, interpretations and optimizing molecular diagnostics tests application.

scholarly journals Application of Loop-Mediated Isothermal Amplification combined with colorimetric and lateral flow dipstick visualization as the potential point-of-care testing for diphtheria

2019 ◽  
Author(s):  
Aleksandra Anna Zasada ◽  
Aldona Wiatrzyk ◽  
Urszula Czajka ◽  
Klaudia Brodzik ◽  
Kamila Formińska ◽  
...  
Keyword(s):  
Detection Limit ◽  
Sensitivity And Specificity ◽  
Point Of Care ◽  
Lamp Assay ◽  
Corynebacterium Diphtheriae ◽  
Lateral Flow ◽  
Isothermal Amplification ◽  
Suspected Case ◽  
Point Of Care Testing ◽  
Loop Mediated Isothermal Amplification

Abstract Background Diphtheria outbreaks occurred in endemic areas and imported and indigenous cases are reported in UE/EEA. Because of the high infectiveness and severity of the disease, early and accurate diagnosis of each suspected case is essential for the treatment and management of the case and close contacts. The aim of the study was to establish simple and rapid testing methods based on Loop-Mediated Isothermal Amplification (LAMP) assay for the detection of Corynebacterium diphtheriae and differentiation between toxigenic and non-toxigenic strains.Methods Corynebacterium diphtheriae and Corynebacterium ulcerans isolates from the National Institute of Public Health-National Institute of Hygiene collection were used for the development of LAMP assay for the diagnosis of diphtheria and nontoxigenic C. diphtheriae infections. Various colorimetric methods for visualization of results were investigated. Sensitivity and specificity of the assay were examined using a collection of DNA samples from various gram-positive and gram-negative bacteria.Results The LAMP assay for tox and dtxR genes was developed. The sensitivity and specificity of the assay were calculated as 100%. The detection limit was estimated as 1.42 pg/µl concentration of DNA template when the reaction was conducted for 60 min. However, the detection limit was lowered 10 times for every 10 minutes of reduction in the time of incubation during the reaction. Positive results were successfully detected colorimetrically using hydroxynaphthol blue, calcein, QuantiFluor, and lateral flow Milenia HybriDetect dipsticks.Conclusion The assay developed in the study might be applied for point-of-care testing of diphtheria and other C. diphtheriae infections. It is highly sensitive, specific, inexpensive, easy to use, and suitable for low-resource settings.

scholarly journals Lateral flow biosensor combined with loop-mediated isothermal amplification for detection of legionella pneumophila.

2021 ◽  
Author(s):  
Luxi Jiang ◽  
Xiaomeng Li ◽  
Rumeng Gu ◽  
Ziling Shi ◽  
Meijun Song ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Culture Method ◽  
Lavage Fluid ◽  
Lateral Flow ◽  
Isothermal Amplification ◽  
Clinical Samples ◽  
Specific Gene ◽  
Minimum Concentration ◽  
Loop Mediated Isothermal Amplification ◽  
Whole Process

Abstract Legionella pneumophila ( L. pneumophila ) is the most pathogenic species of Legionella , which can cause Legionella disease. It can cause pneumonia, or Pontiac fever. In severe cases, it can lead to respiratory failure and kidney failure, with a high fatality rate. Here, a novel molecular diagnosis method, a loop-mediated isothermal amplification coupled with lateral flow biosensor (LFB) method (LAMP-LFB) was successfully established and evaluated for the identification of L. pneumophila . A set of 6 primers was designed specifically based on the L. pneumophila -specific gene mip. The optimized time and temperature conditions for the LAMP was 50 min and 64◦C respectively. The minimum concentration that can be detected by this method was 100fg. Using the protocol, we could observe the LAMP amplification within 2min by LFB. The whole process, including the preparation of DNA (20 min), LAMP reaction (50 min) and results reporting (2 min), could be finished within 75 min. Among 50 alveolar lavage fluid samples, 5(10%) were L. pneumophila -positive by the LAMP-LFB, and the diagnostic accuracy was 100% when compared to the culture method. While only 4 samples were positive using PCR method. In a word, the LAMP-LFB assay is a rapid, sensitive and specific detection method that can detect Legionella pneumophila , and it can be used as a new molecular method for the detection of target pathogens in water, environmental and clinical samples.

Development and application of loop-mediated isothermal amplification label-based nanoparticles lateral flow biosensor for detection of Mycobacterium tuberculosis

2019 ◽  
Author(s):  
Xingyun Wang ◽  
Yi Wang ◽  
Weiwei Jiao ◽  
Guirong Wang ◽  
Yacui Wang ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Diagnostic Technique ◽  
Cost Effective ◽  
Cross Reactivity ◽  
Lateral Flow ◽  
Isothermal Amplification ◽  
Clinical Samples ◽  
High Morbidity ◽  
Analytical Sensitivity ◽  
Loop Mediated Isothermal Amplification

Abstract Tuberculosis is a serious disease with high morbidity and mortality, thus rapid and cost-effective diagnostic test for Mycobacterium tuberculosis (MTB) is urgently needed. Here, a novel detection diagnostic technique, termed as loop-mediated isothermal amplification label-based nanoparticles with lateral flow biosensor (LAMP-LFB), was developed and evaluated for rapid, reliable and objective detection of MTB. Two sets of primers, which targeted IS 6110 and IS 1081 sequences of MTB, were simultaneously designed for establishment of LAMP-LFB assay. The optimal reaction conditions of MTB-LAMP-LFB assay confirmed were 66ºC for only 50min. The analytical sensitivity of MTB-LAMP-LFB is 10fg of genomic templates in pure culture, and the detection results obtained from LFB was in conformity with agarose gel electrophoresis. No cross-reactivity with other common bacteria and non-tuberculous mycobacteria strains (NTM) was obtained. A total of 158 clinical samples were collected from presumptive 158 TB patients, were used for evaluating the feasibility of MTB-LAMP-LFB assay. Among 98 TB patients diagnosed with composite reference standard, the positive rate for MTB detection using liquid culture, Xpert MTB/RIF and LAMP-LFB were 40.0% (39/98), 50.0% (48/98), and 86.7% (85/98), respectively. Among 39 culture confirmed samples, 84.6% (33/39) cases were Xpert MTB/RIF-positive and 92.3% (36/39) were LAMP-LFB-positive. For the 59 clinically diagnosed TB cases 25.4% (15/59) and 83.0% (49/59) were Xpert MTB/RIF-positive and LAMP-LFB positive, respectively. Therefore, MTB-LAMP-LFB assay is a simple, reliable, and sensitive method for MTB detection and maybe prospective in early diagnosis of MTB.

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