scholarly journals Combination of rRT-PCR and Anti-Nucleocapsid/Anti-Spike Antibodies to Characterize Specimens with Very Low Viral SARs-CoV-2 Load: A Real-Life Experience

2021 ◽  
Vol 9 (6) ◽  
pp. 1263
Author(s):  
Zoe Florou ◽  
Meropi Zigra ◽  
Philippos Kartalidis ◽  
Katerina Tsilipounidaki ◽  
Georgia Papadamou ◽  
...  
Keyword(s):  
Viral Load ◽  
Life Experience ◽  
Early Stage ◽  
Real Life ◽  
Serum Specimen ◽  
Chain Reaction ◽  
Serum Samples ◽  
Viral Loads ◽  
Polymerase Chain ◽  
Positive Results

The objective of the present study was to evaluate the true positivity among people, whose results of initial testing of nasopharyngeal swabs (NPS) showed a very low viral load of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Seventy-seven people detected with low viral loads of SARs-CoV-2 in nasopharyngeal samples (Ct ≥ 35) were enrolled in the study. For this purpose, a second NPS was collected for rRT-PCR (real-time reverse transcription polymerase chain reaction) combined with a pair of serum samples for detection of anti-nucleocapsid (anti-N) and anti-spike (anti-S) antibodies. In 8 people, subsequent examinations indicated an increase in viral loads, thereafter, followed by an increase of anti-N and anti-S antibodies, findings compatible with an early stage of COVID-19 infection. In 9 people, who already had increased anti-N antibodies, subsequent examination showed a decrease or absence of viral load and an increase in antibodies, indicative of a late stage of COVID-19 infection. In 60 people, subsequent examination showed absence of infection (as indicated by absence of viral load and antibodies). We propose that the combination of a second NPS and one serum-specimen, both taken three days after the first NPS, helps significantly to avoid false-positive results.

scholarly journals Performance of the Innova SARS-CoV-2 antigen rapid lateral flow test in the Liverpool asymptomatic testing pilot: population based cohort study

BMJ ◽  
2021 ◽  
pp. n1637 ◽  
Author(s):  
Marta García-Fiñana ◽  
David M Hughes ◽  
Christopher P Cheyne ◽  
Girvan Burnside ◽  
Mark Stockbridge ◽  
...  
Keyword(s):  
Polymerase Chain Reaction ◽  
Viral Load ◽  
Predictive Value ◽  
High Viral Load ◽  
Test Results ◽  
Chain Reaction ◽  
Viral Loads ◽  
Flow Test ◽  
Polymerase Chain ◽  
Lateral Flow Test

Abstract Objective To assess the performance of the SARS-CoV-2 antigen rapid lateral flow test (LFT) versus polymerase chain reaction testing in the asymptomatic general population attending testing centres. Design Observational cohort study. Setting Community LFT pilot at covid-19 testing sites in Liverpool, UK. Participants 5869 asymptomatic adults (≥18 years) voluntarily attending one of 48 testing sites during 6-29 November 2020. Interventions Participants were tested using both an Innova LFT and a quantitative reverse-transcriptase polymerase chain reaction (RT-qPCR) test based on supervised self-administered swabbing at testing sites. Main outcome measures Sensitivity, specificity, and predictive values of LFT compared with RT-qPCR in an epidemic steady state of covid-19 among adults with no classic symptoms of the disease. Results Of 5869 test results, 22 (0.4%) LFT results and 343 (5.8%) RT-qPCR results were void (that is, when the control line fails to appear within 30 minutes). Excluding the void results, the LFT versus RT-qPCR showed a sensitivity of 40.0% (95% confidence interval 28.5% to 52.4%; 28/70), specificity of 99.9% (99.8% to 99.99%; 5431/5434), positive predictive value of 90.3% (74.2% to 98.0%; 28/31), and negative predictive value of 99.2% (99.0% to 99.4%; 5431/5473). When the void samples were assumed to be negative, a sensitivity was observed for LFT of 37.8% (26.8% to 49.9%; 28/74), specificity of 99.6% (99.4% to 99.8%; 5431/5452), positive predictive value of 84.8% (68.1% to 94.9%; 28/33), and negative predictive value of 93.4% (92.7% to 94.0%; 5431/5814). The sensitivity in participants with an RT-qPCR cycle threshold (Ct) of <18.3 (approximate viral loads >10 6 RNA copies/mL) was 90.9% (58.7% to 99.8%; 10/11), a Ct of <24.4 (>10 4 RNA copies/mL) was 69.4% (51.9% to 83.7%; 25/36), and a Ct of >24.4 (<10 4 RNA copies/mL) was 9.7% (1.9% to 23.7%; 3/34). LFT is likely to detect at least three fifths and at most 998 in every 1000 people with a positive RT-qPCR test result with high viral load. Conclusions The Innova LFT can be useful for identifying infections among adults who report no symptoms of covid-19, particularly those with high viral load who are more likely to infect others. The number of asymptomatic adults with lower Ct (indicating higher viral load) missed by LFT, although small, should be considered when using single LFT in high consequence settings. Clear and accurate communication with the public about how to interpret test results is important, given the chance of missing some cases, even at high viral loads. Further research is needed to understand how infectiousness is reflected in the viral antigen shedding detected by LFT versus the viral loads approximated by RT-qPCR.

scholarly journals Clinical importance of reporting SARS-CoV-2 viral loads across the different stages of the COVID-19 pandemic

2020 ◽  
Author(s):  
Milo Moraz ◽  
Damien Jacot ◽  
Matthaios Papadimitriou-Olivgeris ◽  
Laurence Senn ◽  
Gilbert Greub ◽  
...  
Keyword(s):  
Viral Load ◽  
Universal Screening ◽  
Clinical Importance ◽  
Screening Strategy ◽  
Rt Pcr ◽  
Chain Reaction ◽  
Viral Loads ◽  
Asymptomatic Patients ◽  
Admission Screening ◽  
Polymerase Chain

On April 25th, corresponding to the first deconfinement phase after the end of the lockdown in Switzerland, a universal admission screening strategy for COVID-19 was introduced in our hospital. All patients, including asymptomatic patients were tested for SARS-CoV-2 by quantitative reverse transcription polymerase chain reaction (RT-PCR). In addition to a qualitative answer, providing viral load values to the RT-PCR results not only helped the clinician to evaluate the stage of the infection but addressed patient contagiousness and guided infection control decisions. Here, we discuss the importance of reporting viral load values when a shift from a symptomatic to a universal screening strategy was performed.

scholarly journals Comparison of SARS-CoV-2 viral load in saliva samples in symptomatic and asymptomatic cases

2021 ◽  
Author(s):  
Anuja Bhatta ◽  
Rebecca Henkhaus ◽  
Heather L. Fehling
Keyword(s):  
Polymerase Chain Reaction ◽  
Viral Load ◽  
Reverse Transcription ◽  
Specific Gene ◽  
Rt Pcr ◽  
Chain Reaction ◽  
Gene Target ◽  
Viral Loads ◽  
Ct Value ◽  
Polymerase Chain

AbstractSARS-CoV-2 infections can be symptomatic as well as asymptomatic. In this study, we analyzed 460,814 saliva samples collected from July 2020 to January 2021 for a SARS-CoV-2-specific gene target using the FDA EUA test, CRL Rapid Response™, based on reverse transcription polymerase chain reaction (RT-PCR). We measured SARS-CoV-2 viral loads using cycle threshold (Ct) values. A total of 17,813 samples tested positive for COVID-19 using self-collected saliva samples. The Ct values ranged from 11 to 40, 91.3% distributed between 22 to 38 Ct. We then compared Ct values for symptomatic and asymptomatic cases for all positive saliva samples. A total of 8,706 cases were symptomatic with an average Ct value of 29.24, and 9,107 cases were asymptomatic with an average Ct value of 30.99. Hence, SARS-CoV-2 viral loads (Ct) in saliva samples for both symptomatic and asymptomatic cases are similar.

scholarly journals Serum lnc34a is a potential prediction biomarker for bone metastasis in hepatocellular carcinoma patients

BMC Cancer ◽  
2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Li Zhang ◽  
Hao Niu ◽  
Ping Yang ◽  
Jie Ma ◽  
Bao-Ying Yuan ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Bone Metastasis ◽  
Univariate Analysis ◽  
High Serum ◽  
Chain Reaction ◽  
Serum Samples ◽  
Early Screening ◽  
Expression Levels ◽  
Node Metastasis ◽  
Polymerase Chain

Abstract Background Early screening and intervention therapies are crucial to improve the prognosis of hepatocellular carcinoma (HCC) patients with bone metastasis. We aimed to identify serum lncRNA as a prediction biomarker in HCC bone metastasis. Methods The expression levels of lnc34a in serum samples from 157 HCC patients were detected by quantitative real-time polymerase chain reaction (PCR). Univariate analysis and multivariate analysis were performed to determine statistically significant variables. Results Expression levels of lnc34a in serum from HCC patients with bone metastasis were significantly higher than those without bone metastasis. The high expressions of lnc34a, vascular invasion and Barcelona Clinic Liver Cancer (BCLC) stage were associated with bone metastasis by analysis. Moreover, lnc34a expression was specifically associated with bone metastasis rather than lung or lymph node metastasis in HCC. Conclusions High serum lnc34a expression was a independent risk factor for developing bone metastasis in HCC.

Identification of Bacteroides forsythus in Subgingival Dental Plaque with the Aid of a Rapid PCR Method

1997 ◽  
Vol 76 (7) ◽  
pp. 1376-1380 ◽  
Author(s):  
J.H. Meurman ◽  
J. Wahlfors ◽  
A. Korhonen ◽  
P. Alakuijala ◽  
P. Väisänen ◽  
...  
Keyword(s):  
Dental Plaque ◽  
Subgingival Plaque ◽  
Chain Reaction ◽  
Rapid Pcr ◽  
Microbiological Methods ◽  
Pcr Method ◽  
Polymerase Chain ◽  
Pre Treatment ◽  
Culture Positive ◽  
Positive Results

Bacteroides forsythus has been shown to be prevalent among patients with periodontitis. Conventional microbiological methods used to identify this bacterium, however, are laborious and time-consuming and are therefore not well-suited for screening purposes. We have developed a polymerase chain-reaction (PCR) method which is rapid, specific, and simple to perform and does not require other sample pre-treatment except a brief centrifugation. This method was applied to the detection of B. forsythus in subgingival plaque of 58 periodontitis patients. When compared with the results of conventional culturing, the PCR method always confirmed the culture-positive results, while none of the PCR negative samples was shown to be culture-positive. The PCR method appeared to give more than double the number of samples positive for B. forsythus than culturing (89.7% vs. 37.9%). The analysis requires less than 4 hrs to perform, and is specific only to B. forsythus and sensitive enough to detect fewer than 5 bacteria.

Studies on Diagnosis of Bovine Brucellosis by Immunocyto-chemistry and Immunohistochemistry

2021 ◽  
Author(s):  
K.S. Lakshmikanth ◽  
N.S. Sharma ◽  
D. Pathak ◽  
Paviter Kaur
Keyword(s):  
Biochemical Analysis ◽  
Placental Tissue ◽  
Diagnostic Techniques ◽  
Clinical Samples ◽  
Bovine Brucellosis ◽  
Reproductive Disorders ◽  
Chain Reaction ◽  
Tissue Samples ◽  
Polymerase Chain ◽  
Positive Results

Background: Brucellosis is a major threat to livestock economy and an important zoonotic disease. A rapid and accurate diagnosis is a necessity to curb the spread and progress of the disease. The current study aimed to evaluate sensitivity of Immunocytochemistry and Immunohistochemistry methods for detection of Brucella spp.Methods: A total of 50 samples comprising of fetal stomach content, vaginal discharges and placenta were collected from cattle and buffaloes suffering from abortions and other reproductive disorders in and around Ludhiana, Punjab during the period 2017-2018. All the samples were processed for isolation and confirmed with biochemical analysis and Polymerase chain reaction (PCR). The isolates obtained and 43 clinical samples excluding placental samples were subjected to Immunocytochemistry (ICC). Immunohistochemistry (ICH) was performed on placental samples.Result: A total of four isolates were recovered from the screened samples. The four isolates also yielded positive results in Immunocytochemistry. Among the 43 clinical samples screened by Immunocytochemistry, five were positive, however only 3 isolates were recovered on isolation. A total of seven placental tissue samples were processed and subjected to immunohistochemistry. Of the three placental samples positive by immunohistochemistry, only one sample was isolated on culture. The results suggest that both immunocytochemistry and immunohistochemistry are sensitive diagnostic techniques in comparison to isolation.

scholarly journals PCR - based diagnosis to evaluate the performance of malaria reference centers

2004 ◽  
Vol 46 (4) ◽  
pp. 183-187 ◽  
Author(s):  
Silvia Maria Di Santi ◽  
Karin Kirchgatter ◽  
Karen Cristina Sant'Anna Brunialti ◽  
Alessandra Mota Oliveira ◽  
Sergio Roberto Santos Ferreira ◽  
...  
Keyword(s):  
Polymerase Chain Reaction ◽  
Gold Standard ◽  
Blood Smear ◽  
Plasmodium Species ◽  
Thick Blood Smear ◽  
Chain Reaction ◽  
Polymerase Chain ◽  
Positive Results ◽  
Ssrrna Gene

Although the Giemsa-stained thick blood smear (GTS) remains the gold standard for the diagnosis of malaria, molecular methods are more sensitive and specific to detect parasites and can be used at reference centers to evaluate the performance of microscopy. The description of the Plasmodium falciparum, P. vivax, P. malariae and P. ovale ssrRNA gene sequences allowed the development of a polymerase chain reaction (PCR) that had been used to differentiate the four species. The objective of this study was to determine Plasmodium species through PCR in 190 positive smears from patients in order to verify the quality of diagnosis at SUCEN's Malaria Laboratory. Considering only the 131 positive results in both techniques, GTS detected 4.6% of mixed and 3.1% of P. malariae infections whereas PCR identified 19.1% and 13.8%, respectively.

scholarly journals An Investigation into the Estimation of a Positive Case of COVID-19: A Comparative Study between Two Phases of the Pandemic

2021 ◽  
Vol 1 (2) ◽  
pp. 85-95
Author(s):  
Yasuyuki Yamaoka ◽  
Hiroko Oe
Keyword(s):  
Insurance Coverage ◽  
Health Insurance Coverage ◽  
Multiple Regression Model ◽  
Unexpected Result ◽  
Actual Number ◽  
Chain Reaction ◽  
Polymerase Chain ◽  
Two Phases ◽  
Positive Results ◽  
Over Time

In Japan, the policy for polymerase chain reaction (hereafter PCR) testing changed significantly after 7 May 2020; from 4 February to 6 May, PCR testing was limited to certain patients with severe symptoms. After 7 May, the PCR test was made available to a broader range of patients due to health insurance coverage. The study aims to test whether there is a significant relationship between the conditions under which PCR tests are performed, the number of tests after 7 May, and the positive results. Using a multiple regression model, we obtained the unexpected result even if we assume that PCR testing had been carried out during 4 February to 6 May at the same level as after 7 May. The number of positive cases would have been even lower than the actual number, which we have attained. This suggests that even if PCR testing had been plentiful throughout the entire period, the number of positives that would have been captured would not necessarily have been more significant than the actual number. This estimation might suggest that the infectivity of COVID-19 varied over time. It may suggest that, over time, the infectiousness and spreading power of COVID may be transformed. Therefore, further research investigating the epidemic impact of COVID is required, which is critical for humankind.

scholarly journals Viral Load Dynamics in Sputum and Nasopharyngeal Swab in Patients with COVID-19

2020 ◽  
Vol 99 (11) ◽  
pp. 1239-1244 ◽  
Author(s):  
R. Liu ◽  
S. Yi ◽  
J. Zhang ◽  
Z. Lv ◽  
C. Zhu ◽  
...  
Keyword(s):  
Viral Load ◽  
Quantitative Polymerase Chain Reaction ◽  
Nasopharyngeal Swab ◽  
Chain Reaction ◽  
Global Pandemic ◽  
Observational Cohort ◽  
Polymerase Chain ◽  
Underlying Diseases ◽  
Temporal Profiles ◽  
Substantial Morbidity

Coronavirus disease 2019 (COVID-19) has caused a global pandemic associated with substantial morbidity and mortality. Nasopharyngeal swabs and sputum samples are generally collected for serial viral load screening of respiratory contagions, but temporal profiles of these samples are not completely clear in patients with COVID-19. We performed an observational cohort study at Renmin Hospital of Wuhan University, which involved 31 patients with confirmed COVID-19 with or without underlying diseases. We obtained samples from each patient, and serial viral load was measured by real-time quantitative polymerase chain reaction. We found that the viral load in the sputum was inclined to be higher than samples obtained from the nasopharyngeal swab at disease presentation. Moreover, the viral load in the sputum decreased more slowly over time than in the nasopharyngeal group as the disease progressed. Interestingly, even when samples in the nasopharyngeal swab turned negative, it was commonly observed that patients with underlying diseases, especially hypertension and diabetes, remained positive for COVID-19 and required a longer period for the sputum samples to turn negative. These combined findings emphasize the importance of tracking sputum samples even in patients with negative tests from nasopharyngeal swabs, especially for those with underlying conditions. In conclusion, this work reinforces the importance of sputum samples for SARS-CoV-2 detection to minimize transmission of COVID-19 within the community.

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