A simple and readily available saline solution can reliably transport COVID-19 samples to testing labs

In the face of dwindling supplies of virus transport media, cheap and readily available phosphate buffered saline can be used to safely store and transport coronavirus samples for up to 18 hours, reports The Journal of Molecular Diagnostics

Philadelphia, May 27, 2020

In a new peer-reviewed study appearing in The Journal of Molecular Diagnostics, published by Elsevier, investigators report that a simple salt solution commonly found in hospitals and clinical laboratories, phosphate buffered saline (PBS), can be used as a medium to reliably transport coronavirus-contaminated specimens to the testing laboratory for periods of up to 18 hours, which is often needed in busy clinical settings.

Clinical specimens suspected to contain viruses are usually shipped to testing laboratories in a complex mixture called virus transport medium (VTM). As the COVID-19 pandemic sweeps across the world, the availability of VTM has become severely limited, contributing to delays in diagnosis and rationing of diagnostic testing. Recognizing that SARS-CoV-2 viral RNA can remain stable on certain surfaces for up to 72 hours, scientists at Rutgers University hypothesized that PBS, which is inexpensive and commonly available in clinical settings, could be used instead.

“Necessity is the mother of invention,” explains senior investigator Martin J. Blaser, MD, Department of Medicine, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, USA; and Center for Advanced Biotechnology and Medicine, Rutgers University, Piscataway, NJ, USA. “We were facing a problem about specimens reaching the lab intact due to the nationwide shortage of VTM, so we endeavored to test a widely available solution to see if it could help us. But first, we had to determine whether or not it worked.”

Swabs obtained from patients must be kept moist and transported to a testing laboratory in a milieu that will preserve the integrity of the specimen.
Credit: Shutterstock.

Three experimental procedures were performed using discarded respiratory secretions from 16 confirmed COVID-19 patients. Swabs were dropped into vials containing either PBS or VTM and transported to the laboratory for analysis using real-time PCR (RT-qPCR) testing to detect the presence of three specific SARS-CoV-2 virus genes in the samples. In the first procedure, eight samples from two subjects were harvested at the same time and transported in either VTM or PTS. The samples were processed immediately or after two hours at room temperature. SARS-CoV-2 was detected in all samples at similar levels for each patient, demonstrating that results were consistent for samples obtained and stored in identical manners.

In a parallel experiment, samples were tested after remaining at room temperature in either PBS or VTM at points ranging from 0-18 hours. These experiments mimicked field conditions, in which specimens may remain in transport for longer periods. Researchers found that storage at room temperature had little effect on the values detected for the three SARS-CoV genes in either PBS or VTM and could be useful for labs that test for several SARS-CoV genes that have different processing times.

The researchers also examined samples transported in both PBS and VTM from an additional 12 patients with unknown viral loads. Again, they found the storage medium did not affect the detectability of the virus.

“That results for all three viral genes tested were strongly correlated across samples from multiple patients support the robustness of the entire testing pathway, including transport, establishing PBS as a dependable transport medium for use with clinical samples,” notes Dr. Blaser. “Our contribution will allow for increased effective testing and transport from relatively long distances to testing labs, at lower cost.”

The researchers note that expanded testing capacity would facilitate more widespread surveillance and containment of COVID-19 in communities, allowing fewer restrictions in work, travel, and social distancing.

“New Jersey has been hit hard by COVID-19,” adds co-lead investigator Jared Radbel, MD, Department of Medicine, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, USA; and Environmental and Occupational Health Sciences Institute, Rutgers University, Piscataway, NJ, USA. “Like other parts of the country, we have had delays in testing. Steps like using alternative materials to increase identification of infected individuals are needed to help clinicians respond to this pandemic illness.”


Notes for editors
The article is “Detection of SARS-CoV-2 is Comparable in Clinical Samples Preserved in Saline or Viral Transport Media,” by Jared Radbel, Sugeet Jagpal, Jason Roy, Andrew Brooks, Jay Tischfield, Michael Sheldon, Christian Bixby, Dana Witt, Maria Laura Gennaro, Daniel B. Horton, Emily S. Barrett, Jeffrey L. Carson, Reynold A. Panettieri Jr., and Martin J. Blaser (https://doi.org/10.1016/j.jmoldx.2020.04.209). It will appear in The Journal of Molecular Diagnostics, volume 22, issue 7 (July 2020) published by Elsevier.

It is openly available at https://www.sciencedirect.com/science/article/pii/S1525157820303238.

This work was funded by: U01AI22285 (MJB), U01HL133817 (JC), UL1TR003017 NCATS (RAP), UH3AI122309 (MLG), P30ES005022 (JR, EB, AB, JT, RP), R01HL149450 (MLG), K23AR070286 (DBH), from the National Institutes of Health.

Full text of this study is also available to credentialed journalists upon request; contact Eileen Leahy at +1 732 238 3628 or jmdmedia@elsevier.com. Journalists wishing to interview the authors should contact Patti Verbanas, Assistant Director of Public and Media Relations, Rutgers Biomedical and Health Sciences, at +1 848 932-0551 or patti.verbanas@rutgers.edu.

Elsevier’s Novel Coronavirus Information Center provides the latest early stage and peer-reviewed research on the novel coronavirus and COVID-19. All resources are free to access and include guidelines for clinicians and patients. The Information Center links to the Coronavirus Hub on ScienceDirect, with more than 26,000 articles relevant to coronavirus, SARS, and MERS freely available. The center also links to a Healthcare Hub with resources for clinicians treating COVID-19 patients. www.elsevier.com/connect/coronavirus-information-center

About The Journal of Molecular Diagnostics
The Journal of Molecular Diagnostics, the official publication of the Association for Molecular Pathology, co-owned by the American Society for Investigative Pathology, and published by Elsevier, seeks to publish high quality original papers on scientific advances in the translation and validation of molecular discoveries in medicine into the clinical diagnostic setting, and the description and application of technological advances in the field of molecular diagnostic medicine. The editors welcome review articles that contain: novel discoveries or clinicopathologic correlations, including studies in oncology, infectious diseases, inherited diseases, predisposition to disease, or the description of polymorphisms linked to disease states or normal variations; the application of diagnostic methodologies in clinical trials; or the development of new or improved molecular methods for diagnosis or monitoring of disease or disease predisposition. jmd.amjpathol.org

About Elsevier
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