scholarly journals An optimised protocol for detection of SARS-CoV-2 in stool

2021 ◽  
Author(s):  
T Li ◽  
E Garcia-Gutierrez ◽  
J Scadden ◽  
J Davies ◽  
C Hutchins ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Rna Extraction ◽  
Extraction Procedure ◽  
Clinical Practices ◽  
Faecal Microbiota ◽  
Chain Reaction ◽  
Oral Transmission ◽  
Viral Particles ◽  
Stool Samples ◽  
Polymerase Chain

AbstractAimSARS-CoV-2 has been detected in stool samples of COVID-19 patients, with potential implications for faecal-oral transmission. Compared to swab samples, the complexity of the stool matrix poses a challenge in the detection of the virus that has not yet been solved. The aim of this study was to establish a sensitive and reliable method for detecting SARS-CoV-2 in stool samples.MethodsStool samples from individuals free of SARS-CoV-2 were homogenised in saline buffer and spiked with a known titre of inactivated virus ranging from 50 to 750 viral particles per 100 mg stool. Debris was removed via centrifugation and supernatants were concentrated by ultrafiltration. RNA was then extracted from the concentrated material using a commercial kit and SARS-CoV-2 was detected via real-time reverse-transcription polymerase chain reaction (RT-qPCR) using the CDC primers and probes.ResultsThe RNA extraction procedure we used allowed the detection of SARS-CoV-2 via RT-qPCR in most of the stool samples tested. We could detect as few as 50 viral particles per 100 mg of stool. However, high variability was observed across samples at low viral titres. The primer set targeting the N1 region provided more reliable and precise results and for this primer set our method had a limit of detection of 1 viral particle per mg of stool.ConclusionsHere we describe a sensitive method for detecting SARS-CoV-2 in stool samples. This method can be used to establish the persistence of SARS-CoV-2 in stool and ensure the safety of clinical practices such as faecal microbiota transplant (FMT).

scholarly journals An optimised protocol for detection of SARS-CoV-2 in stool

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Tianqi Li ◽  
Enriqueta Garcia-Gutierrez ◽  
Daniel A. Yara ◽  
Jacob Scadden ◽  
Jade Davies ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Rna Extraction ◽  
Extraction Procedure ◽  
Nasopharyngeal Swab ◽  
Clinical Practices ◽  
Oral Transmission ◽  
Viral Particles ◽  
Stool Samples ◽  
Polymerase Chain ◽  
Reliable Methods

Abstract Background SARS-CoV-2 has been detected in stool samples of COVID-19 patients, with potential implications for faecal-oral transmission. Compared to nasopharyngeal swab samples, the complexity of the stool matrix poses a challenge in the detection of the virus that has not yet been solved. However, robust and reliable methods are needed to estimate the prevalence and persistence of SARS-CoV-2 in the gut and to ensure the safety of microbiome-based procedures such as faecal microbiota transplant (FMT). The aim of this study was to establish a sensitive and reliable method for detecting SARS-CoV-2 in stool samples. Results Stool samples from individuals free of SARS-CoV-2 were homogenised in saline buffer and spiked with a known titre of inactivated virus ranging from 50 to 750 viral particles per 100 mg stool. Viral particles were concentrated by ultrafiltration, RNA was extracted, and SARS-CoV-2 was detected via real-time reverse-transcription polymerase chain reaction (RT-qPCR) using the CDC primers and probes. The RNA extraction procedure we used allowed for the detection of SARS-CoV-2 via RT-qPCR in most of the stool samples tested. We could detect as few as 50 viral particles per 100 mg of stool. However, high variability was observed across samples at low viral titres. The primer set targeting the N1 region provided more reliable and precise results and for this primer set our method had a limit of detection of 1 viral particle per mg of stool. Conclusions Here we describe a sensitive method for detecting SARS-CoV-2 in stool samples. This method can be used to establish the persistence of SARS-CoV-2 in stool and ensure the safety of clinical practices such as FMT.

scholarly journals A school outbreak of Norwalk-like virus: evidence for airborne transmission

2003 ◽  
Vol 131 (1) ◽  
pp. 727-736 ◽  
Author(s):  
P. J. MARKS ◽  
I. B. VIPOND ◽  
F. M. REGAN ◽  
K. WEDGWOOD ◽  
R. E. FEY ◽  
...  
Keyword(s):  
Odds Ratio ◽  
Adjusted Odds Ratio ◽  
Nucleotide Sequence Analysis ◽  
Chain Reaction ◽  
Epidemiological Features ◽  
Positive Stool ◽  
Viral Particles ◽  
Stool Samples ◽  
Polymerase Chain ◽  
The Times

An outbreak of gastroenteritis affected a school attended by children aged 4–11 years. Epidemiological features suggested this was due to Norwalk-like virus (NLV) and this was confirmed by polymerase chain reaction (PCR). Nucleotide sequence analysis of the PCR amplicons revealed identical strains in all five positive stool samples. Pupils were significantly more likely to become ill following an episode of vomiting within their classroom (adjusted odds ratio 4·1, 95% CI 1·8–9·3). The times from exposure to illness were consistent with direct infection from aerosolized viral particles where exposure to vomiting was high.Cleaning with quaternary ammonium preparations made no impact on the course of the outbreak. However, the outbreak stopped after the school closed for 4 days and was cleaned using chlorine-based agents. This study confirms the importance of vomiting in the transmission of NLV and provides evidence that direct infection with aerosolized viral particles occurs.

scholarly journals Multiplexed and extraction-free amplification for simplified SARS-CoV-2 RT-PCR tests

2020 ◽  
Author(s):  
Samantha A. Byrnes ◽  
Ryan Gallagher ◽  
Amy Steadman ◽  
Crissa Bennett ◽  
Rafael Rivera ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Rna Extraction ◽  
Rapid Onset ◽  
Technical Expertise ◽  
Sample Collection ◽  
Rt Pcr ◽  
Chain Reaction ◽  
Rna Purification ◽  
Polymerase Chain ◽  
Multiple Challenges

The rapid onset of the global COVID-19 pandemic has led to multiple challenges for accurately diagnosing the infection. One of the main bottlenecks for COVID-19 detection is reagent and material shortages for sample collection, preservation, and purification prior to testing. Currently, most authorized diagnostic tests require RNA extraction from patient samples and detection by reverse transcription polymerase chain reaction (RT-PCR). However, RNA purification is expensive, time consuming, and requires technical expertise to perform. Additionally, there have been reported shortages of the RNA purification kits needed for most tests. With these challenges in mind, we report on extraction-free amplification of SARS-CoV-2 RNA directly from patient samples. In addition, we have developed a multiplex RT-PCR using the CDC singleplex targets. This multiplex has a limit of detection of 2 copies/μL. We have demonstrated these improvements to the current diagnostic workflow, which reduce complexity and cost, minimize reagent usage, expedite time to results, and increase testing capacity.

scholarly journals Digital Droplet PCR for SARS-CoV-2 Resolves Borderline Cases

2021 ◽  
Author(s):  
Jing Xu ◽  
Timothy Kirtek ◽  
Yan Xu ◽  
Hui Zheng ◽  
Huiyu Yao ◽  
...  
Keyword(s):  
Polymerase Chain Reaction ◽  
Limit Of Detection ◽  
False Negative ◽  
Accurate Method ◽  
Viral Envelope ◽  
Chain Reaction ◽  
Borderline Cases ◽  
Droplet Pcr ◽  
Polymerase Chain ◽  
Digital Polymerase Chain Reaction

Abstract Objectives The Bio-Rad SARS-CoV-2 ddPCR Kit (Bio-Rad Laboratories) was the first droplet digital polymerase chain reaction (ddPCR) assay to receive Food and Drug Administration (FDA) Emergency Use Authorization approval, but it has not been evaluated clinically. We describe the performance of ddPCR—in particular, its ability to confirm weak-positive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) results. Methods We clinically validated the Bio-Rad Triplex Probe ddPCR Assay. The limit of detection was determined by using serial dilutions of SARS-CoV-2 RNA in an artificial viral envelope. The ddPCR assay was performed according to the manufacturer’s specifications on specimens confirmed to be positive (n = 48) or negative (n = 30) by an FDA-validated reverse transcription–polymerase chain reaction assay on the m2000 RealTime system (Abbott). Ten borderline positive cases were also evaluated. Results The limit of detection was 50 copies/mL (19 of 20 positive). Forty-seven specimens spanning a range of quantification cycles (2.9-25.9 cycle numbers) were positive by this assay (47 of 48; 97.9% positive precent agreement), and 30 negative samples were confirmed as negative (30 of 30; 100% negative percent agreement). Nine of 10 borderline cases were positive when tested in triplicate. Conclusions The ddPCR of SARS-CoV-2 is an accurate method, with superior sensitivity for viral RNA detection. It could provide definitive evaluation of borderline positive cases or suspected false-negative cases.

scholarly journals Seasonal Differences in Cyclospora cayetanensis Prevalence in Colombian Indigenous People

2021 ◽  
Vol 9 (3) ◽  
pp. 627
Author(s):  
Hagen Frickmann ◽  
Juliane Alker ◽  
Jessica Hansen ◽  
Juan Carlos Dib ◽  
Andrés Aristizabal ◽  
...  
Keyword(s):  
Indigenous People ◽  
Rainy Season ◽  
Gastrointestinal Symptoms ◽  
Dry Season ◽  
Seasonal Effects ◽  
Chain Reaction ◽  
Resource Limited Settings ◽  
Resource Limited ◽  
Stool Samples ◽  
Polymerase Chain

Fecal-orally transmitted cyclosporiasis is frequent in remote resource-limited settings in Central and South America with poor hygiene conditions. In this study, we aimed at assessing seasonal effects on the epidemiology of colonization or infection with C. cayetanensis in Colombian indigenous people living under very restricted conditions. In the rainy season between July and November and in the dry season between January and April, stool samples from indigenous people with and without gastrointestinal symptoms were collected and screened for C. cayetanensis applying in-house real-time polymerase chain reaction (PCR). In the rainy season and in the dry season, positive PCR results were observed for 11.8% (16/136) and 5.1% (15/292), respectively, with cycle threshold (Ct) values of 30.6 (±3.4) and 34.4 (±1.6), respectively. Despite higher parasite loads in the rainy season, fewer individuals (2/16, 12.5%) reported gastrointestinal symptoms compared to the dry season (6/15, 40%). In conclusion, considerable prevalence of C. cayetanensis in Colombian indigenous people persists in the dry season. Low proportions of gastrointestinal symptoms along with higher parasite loads make colonization likely rather than infection.

scholarly journals Development of Quantitative Real-Time Polymerase Chain Reaction for Detection of and Discrimination between Erysipelothrix Rhusiopathiae and Other Erysipelothrix Species

2009 ◽  
Vol 21 (5) ◽  
pp. 701-706 ◽  
Author(s):  
Ho To ◽  
Tomohiro Koyama ◽  
Shinya Nagai ◽  
Kotaro Tuchiya ◽  
Tetsuo Nunoya
Keyword(s):  
Polymerase Chain Reaction ◽  
Real Time ◽  
Limit Of Detection ◽  
Enrichment Culture ◽  
Bacterial Species ◽  
Erysipelothrix Rhusiopathiae ◽  
Chain Reaction ◽  
Tissue Samples ◽  
Practical Applications ◽  
Polymerase Chain

Quantitative real-time polymerase chain reaction (qPCR) assays were developed and validated in combination with enrichment culture for the detection and discrimination of Erysipelothrix rhusiopathiae and other Erysipelothrix species from tissue samples. The targets for SYBR green qPCR assays were the 16S ribosomal RNA gene for Erysipelothrix species and a gene involved in capsular formation for E. rhusiopathiae. The specificity of the assays was assessed with Erysipelothrix species and other related bacterial species. The limit of detection was found to be 5 colony-forming units per reaction. Amplification of DNA extracted from spleen and joint samples spiked with increasing quantities of Erysipelothrix cells was shown to be equally sensitive to DNA extracted from a pure bacterial culture. The assays were evaluated with 88 tissue samples from 3 experimentally infected pigs and 50 mice and with 36 tissue samples from 3 naturally infected pigs and 11 noninfected pigs. Results were compared with those of direct qPCR and conventional culture. The qPCR after enrichment increased the diagnostic sensitivity over that of culture and qPCR, thereby significantly reducing the total time taken for the detection of E. rhusiopathiae and other Erysipelothrix species. Therefore, this technique could be used for practical applications.

Comparison of Droplet Digital Polymerase Chain Reaction (ddPCR) and Real-Time Quantitative Polymerase Chain Reaction (qPCR) in Detecting Neonatal Invasive Fungal Infections

2021 ◽  
Vol 11 (3) ◽  
pp. 373-379
Author(s):  
Huitao Li ◽  
Xueyu Chen ◽  
Xiaomei Qiu ◽  
Weimin Huang ◽  
Chuanzhong Yang
Keyword(s):  
Polymerase Chain Reaction ◽  
Limit Of Detection ◽  
Quantitative Polymerase Chain Reaction ◽  
Diagnostic Methods ◽  
Chain Reaction ◽  
Fungal Isolation ◽  
Blood Samples ◽  
Fungal Strains ◽  
Polymerase Chain ◽  
Digital Polymerase Chain Reaction

Invasive fungal infection (IFI) is the leading cause of death in neonatal patients, yet the diagnosis of IFI remains a major challenge. At present, most IFI laboratory diagnostic methods are based on classical, but limited, methods such as fungal isolation and culture and histopathological examination. Recently, quantitative polymerase chain reaction (qPCR) and droplet digital polymerase chain reaction (ddPCR) technology have been adopted to quantify nucleic-acid identification. In this study, we established qPCR and ddPCR assays for IFI diagnosis and quantification. qPCR and ddPCR were carried out using identical primers and probe for the amplification of 18S rRNA. Assay results for three fungal strains were positive, whereas ten non-fungal strains had negative results, indicating 100% specificity for both ddPCR and qPCR methods. Genomic DNA of Candida albicans was tested after a serial dilution to compare the sensitivity of the two PCR methods. The limit of detection of ddPCR was 3.2 copies/L, which was a ten-fold increase compared with that of the qPCR method (32 copies/L). Blood samples from 127 patients with high-risk factors and clinical symptoms for IFI were collected from a NICU in Shenzhen, China, and analyzed using qPCR and ddPCR. Thirty-four blood samples from neonates had a proven or probable diagnosis of IFI, and 25 of these were positive by qPCR, whereas 30 were positive by ddPCR. Among the 93 blood samples from neonates who had a possible IFI or no IFI, 24 were positive using qPCR, and 7 were positive using ddPCR. In conclusion, ddPCR is a rapid and accurate pan-fungal detection method and provides a promising prospect for IFI clinical screening.

scholarly journals Diagnosis of Blastocystis sp., Cryptosporidium sp., and Giardia intestinalis by Multiplex PCR: An Optimization Study

2021 ◽  
Author(s):  
Ali Ahmet Kilimcioğlu ◽  
Nogay Girginkardeşler ◽  
Tuba Oyur ◽  
Selin Bölük Sabuncu ◽  
Didem Düzyol Azak ◽  
...  
Keyword(s):  
Multiplex Pcr ◽  
Dna Isolation ◽  
Giardia Intestinalis ◽  
Molecular Method ◽  
Chain Reaction ◽  
Optimization Study ◽  
Optimized Protocol ◽  
Blastocystis Sp ◽  
Stool Samples ◽  
Polymerase Chain

Objective: It was aimed to develop a new Multiplex Polymerase Chain Reaction (PCR) protocol with isolates obtained from local patients for the diagnosis of Blastocystis sp., Cryptosporidium sp. and Giardia intestinalis, which can cause severe gastrointestinal system complaints especially in immunocompromised patients and children. Method: DNA isolation was performed with a commercial kit from three stool samples of different patients whose microscopic examination showed dense amounts of Blastocystis sp., Cryptosporidium sp. and Giardia intestinalis. First, a special PCR protocol has been developed for each protozoon. Then, the multiplex PCR protocol, in which these three protozoa can be diagnosed together, was optimized. Results: In the multiplex PCR protocol performed after DNA isolation, bands of 95 bp., 227 bp. and 258 bp. were obtained for Cryptosporidium sp., Blastocystis sp. and G. intestinalis, respectively. Conclusion: Blastocystis sp., Cryptosporidium sp. and Giardia intestinalis were diagnosed by multiplex PCR with the original protocol developed. Due to the difficulties in using different methods in parasitological examination, by adding other protozoa important for public health to this optimized protocol, it will be possible to detect a large number of parasites with a single molecular method.

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