scholarly journals A Multi-Country, Single-Blinded, Phase 2 Study to Evaluate a Point-of-Need System for Rapid Detection of Leishmaniasis and Its Implementation in Endemic Settings

2021 ◽  
Vol 9 (3) ◽  
pp. 588
Author(s):  
Prakash Ghosh ◽  
Abhijit Sharma ◽  
Narayan Bhattarai ◽  
Kumar Abhishek ◽  
Thilini Nisansala ◽  
...  
Keyword(s):  
Sri Lanka ◽  
Real Time ◽  
Real Time Pcr ◽  
Evaluation Study ◽  
Nucleic Acid Amplification ◽  
Clinical Samples ◽  
Lower Sensitivity ◽  
Skin Sample ◽  
Diagnostic Efficacy ◽  
Kala Azar

With the advancement of isothermal nucleic acid amplification techniques, detection of the pathogenic DNA in clinical samples at point-of-need is no longer a dream. The newly developed recombinase polymerase amplification (RPA) assay incorporated in a suitcase laboratory has shown promising diagnostic efficacy over real-time PCR in detection of leishmania DNA from clinical samples. For broader application of this point-of-need system, we undertook a current multi-country diagnostic evaluation study towards establishing this technique in different endemic settings which would be beneficial for the ongoing elimination programs for leishmaniasis. For this study purpose, clinical samples from confirmed visceral leishmaniasis (VL) and post-kala-azar dermal leishmaniasis (PKDL) patients were subjected to both real-time PCR and RPA assay in Bangladesh, India, and Nepal. Further skin samples from confirmed cutaneous leishmaniasis (CL) patients were also included from Sri Lanka. A total of 450 clinical samples from VL patients, 429 from PKDL patients, 47 from CL patients, and 322 from endemic healthy/healthy controls were under investigation to determine the diagnostic efficacy of RPA assay in comparison to real-time PCR. A comparative sensitivity of both methods was found where real-time PCR and RPA assay showed 96.86% (95% CI: 94.45–98.42) and 88.85% (95% CI: 85.08–91.96) sensitivity respectively in the diagnosis of VL cases. This new isothermal method also exhibited promising diagnostic sensitivity (93.50%) for PKDL cases, when a skin sample was used. Due to variation in the sequence of target amplicons, RPA assay showed comparatively lower sensitivity (55.32%) than that of real-time PCR in Sri Lanka for the diagnosis of CL cases. Except for India, the assay presented absolute specificity in the rest of the sites. Excellent concordance between the two molecular methods towards detection of leishmania DNA in clinical samples substantiates the application of RPA assay incorporated in a suitcase laboratory for point-of-need diagnosis of VL and PKDL in low resource endemic settings. However, further improvisation of the method is necessary for diagnosis of CL.

Performance evaluation of cobas HBV real-time PCR assay on Roche cobas 4800 System in comparison with COBAS AmpliPrep/COBAS TaqMan HBV Test

2018 ◽  
Vol 56 (7) ◽  
pp. 1133-1139 ◽  
Author(s):  
Hanah Kim ◽  
Mina Hur ◽  
Eunsin Bae ◽  
Kyung-A Lee ◽  
Woo-In Lee
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Limit Of Detection ◽  
Nucleic Acid Amplification ◽  
Coefficient Of Determination ◽  
Clinical Samples ◽  
Pcr Assay ◽  
Cobas Taqman ◽  
Limit Of Quantitation ◽  
Two Systems

Abstract Background: Hepatitis B virus (HBV) nucleic acid amplification testing (NAAT) is important for the diagnosis and management of HBV infection. We evaluated the analytical performance of the cobas HBV NAAT (Roche Diagnostics GmbH, Mannheim, Germany) on the cobas 4800 System in comparison with COBAS AmpliPrep/COBAS TaqMan HBV Test (CAP/CTM HBV). Methods: Precision was evaluated using three levels of cobas HBV/HCV/HIV-1 Control Kit, and linearity was evaluated across the anticipated measuring range (10.0–1.0×109 IU/mL) at seven levels using clinical samples. Detection capability, including limit of blank (LOB), limit of detection (LOD) and limit of quantitation (LOQ), was verified using the 4th WHO International Standard for HBV DNA for NAT (NIBSC code: 10/266). Correlation between the two systems was compared using 205 clinical samples (102 sera and 103 EDTA plasma). Results: Repeatability and total imprecision (coefficient of variation) ranged from 0.5% to 3.8% and from 0.5% to 3.5%, respectively. Linearity (coefficient of determination, R2) was 0.999. LOB, LOD and LOQ were all acceptable within the observed proportion rate (85%). Correlation was very high between the two systems in both serum and plasma samples (correlation coefficient [r]=0.995). Conclusions: The new cobas HBV real-time PCR assay on the cobas 4800 System showed reliable analytical performances.

scholarly journals Antiprimer Quenching-Based Real-Time PCR and Its Application to the Analysis of Clinical Cancer Samples

2006 ◽  
Vol 52 (4) ◽  
pp. 624-633 ◽  
Author(s):  
Jin Li ◽  
Fengfei Wang ◽  
Harvey Mamon ◽  
Matthew H Kulke ◽  
Lyndsay Harris ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Genetic Analysis ◽  
Real Time ◽  
Real Time Pcr ◽  
Low Cost ◽  
Pcr Primers ◽  
Medical Diagnostics ◽  
Nucleic Acid Amplification ◽  
Clinical Samples ◽  
Correct Identification

Abstract Background: Nucleic acid amplification plays an increasingly important role in genetic analysis of clinical samples, medical diagnostics, and drug discovery. We present a novel quantitative PCR technology that combines the advantages of existing methods and allows versatile and flexible nucleic acid target quantification in clinical samples of widely different origin and quality. Methods: We modified one of the 2 PCR primers by use of an oligonucleotide “tail” fluorescently labeled at the 5′ end. An oligonucleotide complementary to this tail, carrying a 3′ quenching molecule (antiprimer), was included in the reaction along with 2 primers. After primer extension, the reaction temperature was lowered such that the antiprimer hybridizes and quenches the fluorescence of the free primer but not the fluorescence of the double-stranded PCR product. The latter provides real-time fluorescent product quantification. This antiprimer-based quantitative real-time PCR method (aQRT-PCR) was used to amplify and quantify minute amounts of input DNA for genes important to cancer. Results: Simplex and multiplex aQRT-PCR demonstrated linear correlation (r2 >0.995) down to a DNA input equivalent to 20 cells. Multiplex aQRT-PCR reliably identified the HER-2 gene in microdissected breast cancer samples; in formalin-fixed, paraffin-embedded specimens; and in plasma circulating DNA from cancer patients. Adaptation to multiplex single-nucleotide polymorphism detection via allele-specific aQRT-PCR allowed correct identification of apolipoprotein B polymorphisms in 51 of 51 human specimens. Conclusion: The simplicity, versatility, reliability, and low cost of aQRT-PCR make it suitable for genetic analysis of clinical specimens.

scholarly journals Molecular Assay for Detection of Genetic Markers Associated with Decreased Susceptibility to Cephalosporins in Neisseria gonorrhoeae

2015 ◽  
Vol 53 (7) ◽  
pp. 2042-2048 ◽  
Author(s):  
S. W. Peterson ◽  
I. Martin ◽  
W. Demczuk ◽  
A. Bharat ◽  
L. Hoang ◽  
...  
Keyword(s):  
Neisseria Gonorrhoeae ◽  
Real Time ◽  
Dna Sequence ◽  
Real Time Pcr ◽  
Nucleic Acid Amplification ◽  
Clinical Samples ◽  
Specific Marker ◽  
Molecular Assay ◽  
Pcr Assay ◽  
Content Type

The incidence of antimicrobial-resistantNeisseria gonorrhoeaecontinues to rise in Canada; however, antimicrobial resistance data are lacking for approximately 70% of gonorrhea infections that are diagnosed directly from clinical specimens by nucleic acid amplification tests (NAATs). We developed a molecular assay for surveillance use to detect mutations in genes associated with decreased susceptibility to cephalosporins that can be applied to both culture isolates and clinical samples. Real-time PCR assays were developed to detect single nucleotide polymorphisms (SNPs) inponA,mtrR,penA,porB, and oneN. gonorrhoeae-specific marker (porA). We tested the real-time PCR assay with 252 gonococcal isolates, 50 nongonococcal isolates, 24N. gonorrhoeae-negative NAAT specimens, and 34N. gonorrhoeae-positive NAAT specimens. Twenty-four of theN. gonorrhoeae-positive NAAT specimens had matched culture isolates. Assay results were confirmed by comparison with whole-genome sequencing data. For 252N. gonorrhoeaestrains, the agreement between the DNA sequence and real-time PCR was 100% forporA,ponA, andpenA, 99.6% formtrR, and 95.2% forporB. The presence of ≥2 SNPs correlated with decreased susceptibility to ceftriaxone (sensitivities of >98%) and cefixime (sensitivities of >96%). Of 24 NAAT specimens with matched cultures, the agreement between the DNA sequence and real-time PCR was 100% forporB, 95.8% forponAandmtrR, and 91.7% forpenA. We demonstrated the utility of a real-time PCR assay for sensitive detection of known markers for the decreased susceptibility to cephalosporins inN. gonorrhoeae. Preliminary results with clinical NAAT specimens were also promising, as they correlated well with bacterial culture results.

scholarly journals Development and Evaluation of Alternative Methods to Identify the Three Most Common Serotypes of Salmonella enterica Causing Clinical Infections in Kazakhstan

2021 ◽  
Vol 9 (11) ◽  
pp. 2319
Author(s):  
Sabyrkhan M. Barmak ◽  
Yuriy A. Sinyavskiy ◽  
Aidar B. Berdygaliev ◽  
Turegeldy Sh. Sharmanov ◽  
Irina S. Savitskaya ◽  
...  
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Salmonella Enterica ◽  
Alternative Methods ◽  
Clinical Samples ◽  
Pcr Analysis ◽  
Screening Methods ◽  
Conventional Pcr ◽  
Diagnostic Efficacy ◽  
Microbial Cells

In this study, we aimed to compare the performance of conventional PCR and real-time PCR assays as screening methods for identification of three frequent, clinically significant Salmonella serovars in Kazakhstan. We determined the diagnostic efficacy of three molecular methods for detection of S. enterica subsp. enterica and typing S. Typhimurium, S. Enteritidis, and S. Virchow. A total of 137 clinical samples and 883 food samples were obtained in Almaty in 2018–2019. All tests showed high analytical specificity for detecting S. enterica and its corresponding serovariants (100%). The sensitivity of real-time PCR for each of the tested targets was 1–10 microbial cells and in conventional PCR 10–100 microbial cells. The trials with conventional PCR and real-time PCR had a diagnostic efficacy (DE) of 100% and 99.71%, respectively. The DE of real-time PCR and conventional PCR for detecting S. Enteritidis and S. Typhimurium was 99.90%, while the DE of conventional PCR and real-time PCR for detecting S. Virchow was 99.31% and 99.80%, respectively. The RAPD-PCR analysis of the genomic DNA of Salmonella enterica showed the genetic kinship of S. Enteritidis isolates, and the genetic heterogeneity of S. Typhimurium and S. Virchow isolates. Thus, the developed methods can be considered as alternatives to classical serotyping using antisera.

scholarly journals Detection of Human Polyomaviruses in Urine from Bone Marrow Transplant Patients: Comparison of Electron Microscopy with PCR

2004 ◽  
Vol 50 (2) ◽  
pp. 306-312 ◽  
Author(s):  
Stefan S Biel ◽  
Andreas Nitsche ◽  
Andreas Kurth ◽  
Wolfgang Siegert ◽  
Muhsin Özel ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Bone Marrow ◽  
Real Time ◽  
Bone Marrow Transplant ◽  
Real Time Pcr ◽  
Marrow Transplant ◽  
Test System ◽  
Urine Samples ◽  
Clinical Samples ◽  
Transplant Patients

Abstract Background: We studied electron microscopy (EM) as an appropriate test system for the detection of polyomavirus in urine samples from bone marrow transplant patients. Methods: We evaluated direct EM, ultracentrifugation (UC) before EM, and solid-phase immuno-EM (SPIEM). The diagnostic accuracy of EM was studied by comparison with a real-time PCR assay on 531 clinical samples. Results: The detection rate of EM was increased by UC and SPIEM. On 531 clinical urine samples, the diagnostic sensitivity of EM was 47% (70 of 149) with a specificity of 100%. We observed a linear relationship between viral genome concentration and the proportion of urine samples positive by EM, with a 50% probability for a positive EM result for urine samples with a polyomavirus concentration of 106 genome-equivalents (GE)/mL; the probability of a positive EM result was 0% for urine samples with <103 GE/mL and 100% for urine samples containing 109 GE/mL. Conclusions: UC/EM is rapid and highly specific for polyomavirus in urine. Unlike real-time PCR, EM has low sensitivity and cannot quantify the viral load.

scholarly journals A Multiplex real-time PCR for detection of Mycoplasma gallisepticum and Mycoplasma synoviae in clinical samples from Brazilian commercial poultry flocks

2013 ◽  
Vol 44 (2) ◽  
pp. 505-510 ◽  
Author(s):  
Aline Padilha Fraga ◽  
Tatiana de Vargas ◽  
Nilo Ikuta ◽  
André Salvador Kazantzi Fonseca ◽  
Álvaro José Celmer ◽  
...  
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Mycoplasma Gallisepticum ◽  
Clinical Samples ◽  
Mycoplasma Synoviae ◽  
Commercial Poultry

scholarly journals Development and evaluation of duplex TaqMan real-time PCR assay for detection and differentiation of wide-type and MGF505-2R gene-deleted African swine fever viruses

2020 ◽  
Author(s):  
zhenhua Guo ◽  
Kunpeng Li ◽  
Songlin Qiao ◽  
Xinxin Chen ◽  
Ruiguang Deng ◽  
...  
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Large Scale ◽  
Limit Of Detection ◽  
African Swine Fever ◽  
Economic Losses ◽  
Clinical Samples ◽  
Diagnosis Method ◽  
Pcr Method ◽  
And Control

Abstract Background: African swine fever (ASF) is the most important disease to the pigs and cause serious economic losses to the countries with large-scale swine production. Vaccines are recognized as the most useful tool to prevent and control ASF virus (ASFV) infection. Currently, the MGF505 and MGF360 gene-deleted ASFVs or combined with CD2v deletion were confirmed to be the most promising vaccine candidates. Thus, it is essential to develop a diagnosis method to discriminate wide-type strain from the vaccines used.Results: In this study, we established a duplex TaqMan real-time PCR based on the B646L gene and MGF505-2R gene. The sequence alignment showed that the targeted regions of primers and probes are highly conserved in the genotype II ASFVs. The duplex real-time assay can specifically detect B646L and MGF505-2R gene single or simultaneously without cross-reaction with other porcine viruses tested. The limit of detection was 5.8 copies and 3.0 copies for the standard plasmids containing B646L and MGF505-2R genes, respectively. Clinical samples were tested in parallel by duplex real-time PCR and a commercial ASFV detection kit. The detection results of these two assays against B646L gene were well consistent.Conclusion: We successfully developed and evaluated a duplex TaqMan real-time PCR method which can effectively distinguish the wide type and MGF505 gene-deleted ASFVs. It would be a useful tool for the clinical diagnosis and control of ASF.

scholarly journals Novel multiplex real-time PCR assays reveal a high prevalence of diarrhoeagenic Escherichia coli pathotypes in healthy and diarrhoeal children in the South of Vietnam

2020 ◽  
Author(s):  
Vu Thuy Duong ◽  
Le Thi Phuong Tu ◽  
Ha Thanh Tuyen ◽  
Le Thi Quynh Nhi ◽  
James I Campbell ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Real Time ◽  
Real Time Pcr ◽  
Clinical Samples ◽  
Middle Income ◽  
Middle Income Countries ◽  
Virulence Markers ◽  
Low Middle Income Countries ◽  
High Prevalence ◽  
Pcr Assays

Abstract BackgroundDiarrhoeagenic Escherichia coli (DEC) infections are common in children in low-middle income countries (LMICs). However, detecting the various DEC pathotypes is complex as they cannot be differentiated by classical microbiology. We developed four multiplex real-time PCR assays were to detect virulence markers of six DEC pathotypes; specificity was tested using DEC controls and other enteric pathogens. PCR amplicons from the six E. coli pathotypes were purified and amplified to be used to optimize PCR reactions and to calculate reproducibility. After validation, these assays were applied to clinical samples from healthy and diarrhoeal Vietnamese children and associated with clinical data. ResultsThe multiplex real-time PCRs were found to be reproducible, and specific. At least one DEC variant was detected in 34.7% (978/2,815) of the faecal samples from diarrhoeal children; EAEC, EIEC and atypical EPEC were most frequent Notably, 41.2% (205/498) of samples from non-diarrhoeal children was positive with a DEC pathotype. In this population, only EIEC, which was detected in 34.3% (99/289) of diarrhoeal samples vs. 0.8% (4/498) non-diarrhoeal samples (p<0.001), was significantly associated with diarrhoea. Multiplex real-time PCR when applied to clinical samples is an efficient and high-throughput approach to DEC pathotypes. ConclusionsThis approach revealed high carriage rates of DEC pathotypes among Vietnamese children. We describe a novel diagnostic approach for DEC, which provides baseline data for future surveillance studies assessing DEC burden in LMICs.

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