VALIDATION OF A SALIVA-BASED TEST FOR THE MOLECULAR DIAGNOSIS OF SARS-CoV-2 INFECTION

Background: Since the beginning of the pandemic, clinicians and researchers have been searching for alternative tests to improve screening and diagnosis of SARS-CoV-2 infection. Currently, the gold standard for virus identification is the nasopharyngeal (NP) swab. Saliva samples, however, offer clear practical and logistical advantages but due to lack of collection, transport, and storage solutions, high-throughput saliva-based laboratory tests are difficult to scale up as a screening or diagnostic tool. With this study, we aimed to validate an intra-laboratory molecular detection method for SARS-CoV-2 on saliva samples collected in a new storage and inactivating solution, comparing the results to NP swabs to determine the difference in sensitivity between the two tests. Methods: In this study, 156 patients (cases) and 1005 asymptomatic subjects (controls) were enrolled and tested simultaneously for the detection of the SARS-CoV-2 viral genome by RT-PCR on both NP swab and saliva samples. Saliva samples were collected in a preservative and inhibiting saline solution (Biofarma Srl). Internal method validation was performed to standardize the entire workflow for saliva samples. Results: The identification of SARS-CoV-2 conducted on saliva samples showed a clinical sensitivity of 95.1% and specificity of 97.8% compared to NP swabs. The positive predictive value (PPV) was 81% while the negative predictive value (NPV) was 99.5%. Test concordance was 97.6% (Cohen's Kappa=0.86; 95% CI 0.81-0.91). The LoD of the test was 5 viral copies for both samples. Conclusions: RT-PCR assays conducted on a stored saliva sample achieved similar performance to those on NP swabs and this may provide a very effective tool for population screening and diagnosis. Collection of saliva in a stabilizing solution makes the test more convenient and widely available; furthermore, the denaturation properties of the solution reduces the infective risks belonging to sample manipulation.

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Validation of a Saliva-Based Test for the Molecular Diagnosis of SARS-CoV-2 Infection

Disease Markers ◽

10.1155/2022/6478434 ◽

2022 ◽

Vol 2022 ◽

pp. 1-8

Author(s):

Michela Bulfoni ◽

Emanuela Sozio ◽

Barbara Marcon ◽

Maria De Martino ◽

Daniela Cesselli ◽

...

Keyword(s):

Predictive Value ◽

Saline Solution ◽

Saliva Sample ◽

Scale Up ◽

Rt Pcr ◽

Clinical Sensitivity ◽

Virus Identification ◽

Stabilizing Solution ◽

The Difference ◽

Screening And Diagnosis

Background. Since the beginning of the pandemic, clinicians and researchers have been searching for alternative tests to improve the screening and diagnosis of the SARS-CoV-2 infection. Currently, the gold standard for virus identification is the nasopharyngeal (NP) swab. Saliva samples, however, offer clear, practical, and logistical advantages but due to a lack of collection, transport, and storage solutions, high-throughput saliva-based laboratory tests are difficult to scale up as a screening or diagnostic tool. With this study, we aimed to validate an intralaboratory molecular detection method for SARS-CoV-2 on saliva samples collected in a new storage saline solution, comparing the results to NP swabs to determine the difference in sensitivity between the two tests. Methods. In this study, 156 patients (cases) and 1005 asymptomatic subjects (controls) were enrolled and tested simultaneously for the detection of the SARS-CoV-2 viral genome by RT-PCR on both NP swab and saliva samples. Saliva samples were collected in a preservative and inhibiting saline solution (Biofarma Srl). Internal method validation was performed to standardize the entire workflow for saliva samples. Results. The identification of SARS-CoV-2 conducted on saliva samples showed a clinical sensitivity of 95.1% and specificity of 97.8% compared to NP swabs. The positive predictive value (PPV) was 81% while the negative predictive value (NPV) was 99.5%. Test concordance was 97.6% (Cohen’s Kappa = 0.86 ; 95% CI 0.81-0.91). The LoD of the test was 5 viral copies for both samples. Conclusions. RT-PCR assays conducted on a stored saliva sample achieved similar performance to those on NP swabs, and this may provide a very effective tool for population screening and diagnosis. Collection of saliva in a stabilizing solution makes the test more convenient and widely available; furthermore, the denaturing properties of the solution reduce the infective risks belonging to sample manipulation.

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Evaluation of accuracy, exclusivity, limit-of-detection and ease-of-use of LumiraDx™ - Antigen-detecting point-of-care device for SARS-CoV-2

10.1101/2021.03.02.21252430 ◽

2021 ◽

Author(s):

Lisa Johanna Krüger ◽

Julian A.F. Klein ◽

Frank Tobian ◽

Mary Gaeddert ◽

Federica Lainati ◽

...

Keyword(s):

Viral Load ◽

Limit Of Detection ◽

Point Of Care ◽

Scale Up ◽

Cross Reactivity ◽

Ease Of Use ◽

Analytical Sensitivity ◽

Rt Pcr ◽

Clinical Sensitivity ◽

Lateral Flow Assays

Background: Rapid antigen-detecting tests (Ag-RDTs) for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can transform pandemic control. Thus far, sensitivity (≤85%) of lateral-flow assays has limited scale-up. Conceivably, microfluidic immunofluorescence Ag-RDTs could increase sensitivity for SARS-CoV-2 detection. Materials and Methods: This multi-centre diagnostic accuracy study investigated performance of the microfluidic immunofluorescence LumiraDx™ assay, enrolling symptomatic and asymptomatic participants with suspected SARS-CoV-2 infection. Participants collected a supervised nasal mid-turbinate (NMT) self-swab for Ag-RDT testing, in addition to a professionally-collected nasopharyngeal (NP) swab for routine testing with reverse transcriptase polymerase chain reaction (RT-PCR). Results were compared to calculate sensitivity and specificity. Sub-analyses investigated the results by viral load, symptom presence and duration. An analytical study assessed exclusivity and limit-of-detection (LOD). In addition, we evaluated ease-of-use. Results: Study conduct was between November 2nd 2020 and January 21st 2021. 761 participants were enrolled, with 486 participants reporting symptoms on testing day. 120 out of 146 RT-PCR positive cases were detected positive by LumiraDx™, resulting in a sensitivity of 82.2% (95% CI: 75.2%-87.5%). Specificity was 99.3% (CI: 98.3-99.7%). Sensitivity was increased in individuals with viral load ≥ 7 log10 SARS-CoV2 RNA copies/ml (93.8%; CI: 86.2%-97.3%). Testing against common respiratory commensals and pathogens showed no cross-reactivity and LOD was estimated to be 2-56 PFU/mL. The ease-of-use-assessment was favourable for lower throughput settings. Conclusion: The LumiraDx™ assay showed excellent analytical sensitivity, exclusivity and clinical specificity with good clinical sensitivity using supervised NMT self-sampling.

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What do we know about smell and taste dysfunction by SARS-CoV-2. Predictive Value of the Venezuelan Olfactory test and RT-PCR analysis in viral infection diagnosis

10.1101/2020.11.25.20238998 ◽

2020 ◽

Author(s):

Rosalinda Pieruzzini ◽

Carlos Ayala-Grosso ◽

Jose de Jesus Navas ◽

Wilneg Rodríguez ◽

Nathalia Parra ◽

...

Keyword(s):

Predictive Value ◽

Early Stage ◽

Polymerase Chain Reaction Analysis ◽

Pcr Analysis ◽

Rt Pcr ◽

Taste Test ◽

Molecular Tests ◽

Olfactory Test ◽

Taste Disorders ◽

Asymptomatic Subjects

SUMMARYBackgroundSmell and taste disorders are reported very frequently and at an early stage in the evolution of the infectious disease caused by the SARS-CoV-2. These symptoms could be sensitive and specific to establish the condition of the infection, and may suggest the flow of decisions as to further therapy. We asked whether smell and taste impairment are earlier and more sensitive symptoms than the RT-PCR molecular assays for SARS-CoV-2 detection.MethodologySubjects (N=275) with a probable COVID19 diagnosis were classified as follows: Symptomatic with chemosensory dysfunction, symptomatic without chemosensory dysfunction, and asymptomatic. Subjects received a general clinical and otorhinolaryngology examination. Evaluation of the chemosensory dysfunction was performed by means of the Venezuelan Olfactory Test and taste test. Nasal swabs and blood samples were analyzed by real-time polymerase chain reaction analysis (RT-PCR) and a rapid diagnostic test to detect the SARS-CoV-2 virus and antiviral antibodies, respectively. Patients had access to molecular tests and smell and taste evaluations every 3 to 5 days until they recovered.ResultsOut of 44 patients that were positive for RT-PCR SARS-CoV-2: 45.83% had smell and taste disorders and COVID19 symptoms, 23.61% did not have smell or taste disorders, but had COVID19 symptoms, and 30.55% were asymptomatic. Mild hyposmia and hypogeusia account for the most frequent chemosensory disorders accompanying common SARS-CoV-2 symptoms. Time to recover from the chemosensory dysfunction ranges from 3 to 14 days, up to a maximum of 5 weeks, while RT-PCR becomes negative after 21 days and up to 35 days in some cases. The Venezuelan Olfactory Test and taste test has a 61.68% positive predictive value, 45.83% sensitivity, and 68.7% specificity for SARS-CoV-2 infection.ConclusionsSmell and taste disorders are frequent symptoms of SARS-CoV-2 infection, but not a significant predictor of the disease, as compared to the molecular RT-PCR test.

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Evaluation of accuracy, exclusivity, limit-of-detection and ease-of-use of LumiraDx™: An antigen-detecting point-of-care device for SARS-CoV-2

Infection ◽

10.1007/s15010-021-01681-y ◽

2021 ◽

Author(s):

Lisa J. Krüger ◽

Julian A. F. Klein ◽

Frank Tobian ◽

Mary Gaeddert ◽

Federica Lainati ◽

...

Keyword(s):

Viral Load ◽

Limit Of Detection ◽

Point Of Care ◽

Scale Up ◽

Cross Reactivity ◽

Ease Of Use ◽

Analytical Sensitivity ◽

Rt Pcr ◽

Clinical Sensitivity ◽

Lateral Flow Assays

Abstract Purpose Rapid antigen-detecting tests (Ag-RDTs) for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can transform pandemic control. Thus far, sensitivity (≤ 85%) of lateral-flow assays has limited scale-up. Conceivably, microfluidic immunofluorescence Ag-RDTs could increase sensitivity for SARS-CoV-2 detection. Methods This multi-centre diagnostic accuracy study investigated performance of the microfluidic immunofluorescence LumiraDx™ assay, enrolling symptomatic and asymptomatic participants with suspected SARS-CoV-2 infection. Participants collected a supervised nasal mid-turbinate (NMT) self-swab for Ag-RDT testing, in addition to a professionally collected nasopharyngeal (NP) swab for routine testing with reverse transcriptase polymerase chain reaction (RT-PCR). Results were compared to calculate sensitivity and specificity. Sub-analyses investigated the results by viral load, symptom presence and duration. An analytical study assessed exclusivity and limit-of-detection (LOD). In addition, we evaluated ease-of-use. Results The study was conducted between November 2nd 2020 and 4th of December 2020. 761 participants were enrolled, with 486 participants reporting symptoms on testing day. 120 out of 146 RT-PCR positive cases were detected positive by LumiraDx™, resulting in a sensitivity of 82.2% (95% CI 75.2–87.5%). Specificity was 99.3% (CI 98.3–99.7%). Sensitivity was increased in individuals with viral load ≥ 7 log10 SARS-CoV2 RNA copies/ml (93.8%; CI 86.2–97.3%). Testing against common respiratory commensals and pathogens showed no cross-reactivity and LOD was estimated to be 2–56 PFU/mL. The ease-of-use-assessment was favourable for lower throughput settings. Conclusion The LumiraDx™ assay showed excellent analytical sensitivity, exclusivity and clinical specificity with good clinical sensitivity using supervised NMT self-sampling. Trial registration number and registration date DRKS00021220 and 01.04.2020

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Dynamic Scintigraphy of the Oesophagus in the Evaluation of Reflux Oesophagitis

Nuklearmedizin ◽

10.1055/s-0038-1629532 ◽

1990 ◽

Vol 29 (05) ◽

pp. 204-209

Author(s):

B. Ugarković ◽

D. Ivančević ◽

D. Babić ◽

Ž. Babić

Keyword(s):

Reflux Oesophagitis ◽

Oesophageal Reflux ◽

Low Grade ◽

Time Activity ◽

The Difference ◽

Asymptomatic Subjects ◽

Oesophageal Transit ◽

Dynamic Scintigraphy ◽

Positive Results ◽

Reflux Œsophagitis

A method is presented which combines gastro-oesophageal reflux quantification and oesophageal transit measurement so as to differentiate true reflux from residual oesophageal activity. A group of 33 subjects with gastro-oesophageal reflux symptoms and endoscopically confirmed reflux oesophagitis and a group of 21 asymptomatic subjects with normal oesophageal, gastric and duodenal endoscopic findings were examined. The subjects were given 37 MBq 99mTc-Sn-colloid in saline orally and then scintiscanned dynamically. The gastro-oesophageal quantification was done after transit measurement and after the oesophageal time activity (to detect residual oesophageal activity) reached its minimum. The difference in the reflux indices between the two groups was highly significant. In low-grade oesophagitis measured reflux was lower than in higher grades of disease. Only 4.7% false-positive results were observed with a specificity of 95%, indicating that this method may be superior to methods published earlier.

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Diagnosis of cerebral hemorrhage before the era of computed tomography

Orvosi Hetilap ◽

10.1556/oh.2013.29739 ◽

2013 ◽

Vol 154 (44) ◽

pp. 1743-1746

Author(s):

Gergely Hofgárt ◽

Rita Szepesi ◽

Bertalan Vámosi ◽

László Csiba

Keyword(s):

Computed Tomography ◽

Cerebrospinal Fluid ◽

Positive Predictive Value ◽

Predictive Value ◽

Hemorrhagic Stroke ◽

Cranial Computed Tomography ◽

Cerebral Stroke ◽

Daily Routine ◽

Stroke Patients ◽

The Difference

Introduction: During the past decades there has been a great progress in neuroimaging methods. Cranial computed tomography is part of the daily routine now and its use allows a fast diagnosis of parenchymal hemorrhage. However, before the availability of computed tomography the differentiation between ischemic and hemorrhagic stroke was based on patient history, physical examination, percutan angiography and cerebrospinal fluid sampling, and the clinical utility could be evaluated by autopsy of deceased patients. Aim: The authors explored the diagnostic performance of cerebrospinal fluid examination for the diagnosis of ischemic and hemorrhagic stroke. Method: Data of 200 deceased stroke patients were retrospectively evaluated. All patients had liquor sampling at admission and all of them had brain autopsy. Results: Bloody or yellowish cerebrospinal fluid at admission had a positive predictive value of 87.5% for hemorrhagic stroke confirmed by autopsy, while clear cerebrospinal fluid had positive predictive value of 90.7% for ischemic stroke. Patients who had clear liquor, but autopsy revealed hemorrhagic stroke had higher protein level in the cerebrospinal fluid, but the difference was not statistically significant (p = 0.09). Conclusions: The results confirm the importance of pathological evaluation of the brain in cases deceased from cerebral stroke. With this article the authors wanted to salute for those who contributed to the development of the Hungarian neuropathology. In this year we remember the 110th anniversary of the birth, and the 60th anniversary of the death of professor Kálmán Sántha. Professor László Molnár would be 90 years old in 2013. Orv. Hetil., 154 (44), 1743–1746.

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Evaluation of aseptic loosening of knee prostheses by quantitative bone scintigraphy

Nuklearmedizin ◽

10.3413/nukmed-0123 ◽

2008 ◽

Vol 47 (04) ◽

pp. 163-166 ◽

Cited By ~ 6

Author(s):

D. Steiner ◽

S. Laurich ◽

R. Bauer ◽

J. Kordelle ◽

R. Klett

Keyword(s):

Aseptic Loosening ◽

Bone Scintigraphy ◽

Revision Surgery ◽

Predictive Value ◽

Knee Prostheses ◽

Treatment Regimes ◽

Golden Standard ◽

The Difference ◽

Sensitivity Specificity ◽

Asymptomatic Control

SummaryIn not infected knee prostheses bone scintigraphy is a possible method to diagnose mechanical loosening, and therefore, to affect treatment regimes in symptomatic patients. However, hitherto studies showed controversial results for the reliability of bone scintigraphy in diagnosing loosened knee prostheses by using asymptomatic control groups. Therefore, the aim of our study was to optimize the interpretation procedure and to evaluate the accuracy using results from revision surgery as standard. Methods: Retrospectively, we were able to examine the tibial component in 31 cemented prostheses. In this prostheses infection was excluded by histological or bacteriological examination during revision surgery. To quantify bone scintigraphy, we used medial and lateral tibial regions with a reference region from the contralateral femur. Results: To differentiate between loosened and intact prostheses we found a threshold of 5.0 for the maximum tibia to femur ratio of the both tibial regions and a threshold of 18% for the difference of the ratio of both tibial regions. Using these thresholds, values of 0.9, 1, 0.85, 1, and 0.94 were calculated for sensitivity, specificity, negative predictive value, positive predictive value, and accuracy, respectively. To get a sensitivity of 1, we found a lower threshold of 3.3 for the maximum tibia to femur ratio. Conclusion: Quantitative bone scintigraphy appears to be a reliable diagnostic tool for aseptic loosening of knee prostheses with thresholds evaluated by revision surgery results being the golden standard.

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Antibiotic Susceptibility Evaluation of Bacterial Agents Causing Infection in Children with Acute Tonsillopharyngitis

Infectious Disorders - Drug Targets ◽

10.2174/1871526520666201116102441 ◽

2020 ◽

Vol 20 ◽

Author(s):

Hamidreza Sherkatolabbasieh ◽

Majid Firouzi ◽

Shiva Shafizadeh ◽

Iman Amiri

Keyword(s):

Sore Throat ◽

Predictive Value ◽

Positive Culture ◽

Clinical Score ◽

Streptococcal Pharyngitis ◽

Diffusion Method ◽

Disk Diffusion Method ◽

Cross Sectional ◽

Clinical Sensitivity ◽

Group A

Background: The aim of this study is to evaluate the prevalence of group A beta-hemolytic pharyngitis by assessing the outcome of the culture and the resistance and sensitivity of group A beta hemolytic streptococcus to antibiotics. Methods: This cross-sectional study was conducted on 170 patients, aged 3-15 years, referred to the clinic with complaints of sore throat. Patients’ history was collected and physical examination was performed and were score based on clinical findings. Patients with other underlying pathologies and those taking antibiotics prior to the study were excluded from our study. Antimicrobial susceptibility test was performed by disk diffusion method against cephalexin, cefazolin, erythromycin and amoxicillin. Results: A total of 170 patients were reported with sore throat. Patients with positive culture results were 60% male and 40% female. Amoxicillin resistance was the greatest (5%) in the culture. All isolated bacteria were sensitive to amoxicillin, cephalexin, cefazolin and erythromycin. Patients with McIssac score ≥ 6 showed clinical sensitivity 75% specificity 61% negative predictive value 94.8% and positive predictive value 20.3% for Group A beta-hemolytic streptococcal pharyngitis. Conclusion: The results showed the higher the clinical score, the greater the chance of positive throat culture.

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Implementing SARS-CoV-2 Rapid Antigen Testing in the Emergency Ward of a Swiss University Hospital: The INCREASE Study

Microorganisms ◽

10.3390/microorganisms9040798 ◽

2021 ◽

Vol 9 (4) ◽

pp. 798

Author(s):

Giorgia Caruana ◽

Antony Croxatto ◽

Eleftheria Kampouri ◽

Antonios Kritikos ◽

Onya Opota ◽

...

Keyword(s):

Immunoglobulin A ◽

University Hospital ◽

Lower Sensitivity ◽

Clinical Settings ◽

Rt Pcr ◽

Emergency Ward ◽

Viral Loads ◽

Asymptomatic Patients ◽

Asymptomatic Subjects ◽

Antigen Testing

Following the Swiss Federal Office of Public Health (FOPH) authorization of the rapid antigen test (RAT), we implemented the use of the RAT in the emergency ward of our university hospital for patients’ cohorting. RAT triaging in association with RT-PCR allowed us to promptly isolate positive patients and save resources. Among 532 patients, overall sensitivities were 48.3% for Exdia and 41.2% for Standard Q®, PanbioTM and BD Veritor™. All RATs exhibited specificity above 99%. Sensitivity increased to 74.6%, 66.2%, 66.2% and 64.8% for Exdia, Standard Q®, PanbioTM and BD Veritor™, respectively, for viral loads above 105 copies/mL, to 100%, 97.8%, 96.6% and 95.6% for viral loads above 106 copies/mL and 100% for viral loads above 107 copies/mL. Sensitivity was significantly higher for patients with symptoms onset within four days (74.3%, 69.2%, 69.2% and 64%, respectively) versus patients with the evolution of symptoms longer than four days (36.8%, 21.1%, 21.1% and 23.7%, respectively). Among COVID-19 asymptomatic patients, sensitivity was 33%. All Immunoglobulin-A-positive patients resulted negative for RAT. The RAT might represent a useful resource in selected clinical settings as a complementary tool in RT-PCR for rapid patient triaging, but the lower sensitivity, especially in late presenters and COVID-19 asymptomatic subjects, must be taken into account.

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Triage of Patients Suspected of COVID-19 in Chronic Hemodialysis: Eosinophil Count Differentiates Low and High Suspicion of COVID-19

Journal of Clinical Medicine ◽

10.3390/jcm10010004 ◽

2020 ◽

Vol 10 (1) ◽

pp. 4

Author(s):

Romain Vial ◽

Marion Gully ◽

Mickael Bobot ◽

Violaine Scarfoglière ◽

Philippe Brunet ◽

...

Keyword(s):

Predictive Value ◽

Eosinophil Count ◽

Characteristic Curve ◽

Final Analysis ◽

Hemodialysis Patients ◽

Chronic Hemodialysis ◽

Screening Methods ◽

Dialysis Session ◽

Diagnostic Study ◽

Rt Pcr

Background: Daily management to shield chronic dialysis patients from SARS-CoV-2 contamination makes patient care cumbersome. There are no screening methods to date and a molecular biology platform is essential to perform RT-PCR for SARS-CoV-2; however, accessibility remains poor. Our goal was to assess whether the tools routinely used to monitor our hemodialysis patients could represent reliable and quickly accessible diagnostic indicators to improve the management of our hemodialysis patients in this pandemic environment. Methods: In this prospective observational diagnostic study, we recruited patients from La Conception hospital. Patients were eligible for inclusion if suspected of SARS-CoV-2 infection when arriving at our center for a dialysis session between March 12th and April 24th 2020. They were included if both RT-PCR result for SARS-CoV-2 and cell blood count on the day that infection was suspected were available. We calculated the area under the curve (AUC) of the receiver operating characteristic curve. Results: 37 patients were included in the final analysis, of which 16 (43.2%) were COVID-19 positive. For the day of suspected COVID-19, total leukocytes were significantly lower in the COVID-19 positive group (4.1 vs. 7.4 G/L, p = 0.0072) and were characterized by lower neutrophils (2.7 vs. 5.1 G/L, p = 0.021) and eosinophils (0.01 vs. 0.15 G/L, p = 0.0003). Eosinophil count below 0.045 G/L identified SARS-CoV-2 infection with AUC of 0.9 [95% CI 0.81—1] (p < 0.0001), sensitivity of 82%, specificity of 86%, a positive predictive value of 82%, a negative predictive value of 86% and a likelihood ratio of 6.04. Conclusions: Eosinophil count enables rapid routine screening of symptomatic chronic hemodialysis patients suspected of being COVID-19 within a range of low or high probability.

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