Diagnostic accuracy of saliva as a specimen for detection of SARS-CoV-2 by RT-PCR.

Context: COVID-19 caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is an emerging pandemic that is rapidly spreading with more than 114 million confirmed cases and 2.5 million deaths by far. Nasopharyngeal swab (NPS) in VTM has been used as the gold standard respiratory specimen for SARS-CoV-2 reverse-transcriptase real-time PCR (rRT-PCR) tests. But now the virus can also be detected in other clinical specimens like bronchoalveolar lavage, sputum, saliva, throat swab, blood, and stool specimens. Aims: The aim of this study was to determine the diagnostic potential of saliva as a sample in comparison to NPS for detection of SARS-CoV-2 by rRT-PCR. Settings and Design: A cross-sectional study was conducted among 256 paired samples (NPS and Saliva) received in the Department of Microbiology, SMS Medical College, Jaipur over a period of 2 months. Methods and Material: NPS from individuals were collected in a sterile tube containing Viral Transport Medium™. Before swab collection, whole saliva was collected by spitting from the suspected patient into a sterile container. Both were stored at room temperature and transferred to the diagnostic laboratory within four hours of collection where extraction was done using Perkin Elmer chemagic extractor and rRT- PCR was performed using NIV, Pune mastermix. Results: Sensitivity, specificity, PPV, and NPV of RT-PCR for the diagnosis of COVID-19 in saliva were 84.26%, 100%, 100%, and 54.05%, respectively. The accuracy of detection of COVID-19 by saliva samples compared to the routinely used NPS samples (considered as the standard reference) for RT PCR was 86.72%. Conclusions: Our results show that saliva as a reliable sample type for SARS-CoV-2 detection.

Evaluation of Saline as Potential Alternative to Viral Transport Media for COVID-19 Samples Stored at Different Temperatures

Introduction: Severe acute respiratory syndrome coronavirus-2 (SARS CoV 2) virus, a causative agent of COVID-19 has led to universal pandemic. During this pandemic there has been an acute shortage of good quality Viral Transport Medium (VTM) because of increase in number of infected people worldwide. It is also difficult to maintain the transport and storing conditions in line with the guidelines in pandemics. Aim: To assess the feasibility of Oropharyngeal Swab (OP)/Nasal swabs in 0.9% normal saline in place of VTM and to analyse the effect of temperature on nucleic acid detection by rRT PCR on saline samples stored at 4°C, ambient and at higher temperature (37°C). Materials and Methods: The present study was an observational analytical study which included 94 positive and 5 negative samples. Patients' nasal or OP samples were collected as dry swabs and in VTM. Normal saline was added once the samples were received in the laboratory. PCR was done with saline and VTM samples both on day 1. Samples were aliquotted in 3 sets and one set was kept at 4°-8° C and other two at 25°C and 37°C, respectively. All positive samples were further tested on day 3, day 4 and day 6. Results were analysed and compared. Results: Samples in normal saline showed very good sensitivity at all temperatures (4°-8°C, 25°C and 37°C) till day 6. Both the swab samples (in saline and in VTM) showed nearly 100% agreement in rRT-PCR results. Ct value variation was also =±2. Conclusion: Looking into the cost and logistics issues especially during pandemics, saline is a good and cheaper alternative to VTM and with its use, testing capacity can be expanded. [ABSTRACT FROM AUTHOR] Copyright of Journal of Clinical & Diagnostic Research is the property of JCDR Research & Publications Private Limited and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)