By Benjamin Ross
April 22, 2020 | MicroGenDX has validated a real-time Reverse Transcriptase PCR (rRT-PCR) assay for the specific detection of the COVID-19 virus. MicroGenDX’s Lubbock, Texas-based lab is conducting COVID-19 testing using sputum samples, which the company’s CEO, Rick Martin, says is one of the more effective methods of testing for the virus.
“[COVID-19] is being spread by people opening their mouth and talking, coughing and sneezing,” Martin told Diagnostics World News. “The amount of viral load that comes out of their mouth is not sitting in their tissue, it’s sitting in their saliva.”
Martin is wary of current regulations saying nasal swab is the way to go for sample collection, saying there’s a lack of data on the subject.
“Someone from the CDC decided nasal swab is the best sample type, and then the FDA followed lock-step and said nasal swab is the way to go. But where’s the data of sample detection levels to show that that’s the optimal sample type?”
Martin is emphatic: “The optimal sample type is sputum.”
Martin points to a March 11 JAMA study (DOI: doi:10.1001/jama.2020.3786), which indicates that, after bronchoalveolar lavage, sputum collection is the most consistent sample method for COVID-19. While other laboratories and tests rely on nasal and throat swabs, MicroGenDX designed their COVID-19 collection method around sputum to more accurately identify the COVID-19 virus.
“From our own analysis, our detection rates went from 8,000 particles with a simple mucus sample to 138,000 particles in a sputum sample,” Martin said. (Sputum is the mixture of saliva and mucus.) “The reason for this is because RNA extraction is a lot easier with saliva than it is with mucus, meaning you’re getting a higher viral load.”
MicroGenDX planned the collection technique around saliva and sputum to prevent reliance on supply materials currently in shortage such as swabs. The laboratory’s solution was to validate sterile saline as a viable transport media for testing.
“We knew swabs were going to be in short supply,” Martin said. “We’ve been taking swab samples for ten years for sinus infections, and we buy swabs on a regular basis. We were looking at our inventory and our suppliers and seeing that everything was back ordered.”
LDT With 24-Hour Turnaround
MicroGenDX runs its COVID-19 Rapid PCR Test at its diagnostic laboratory in with a 24-hour turnaround from time of sample receipt. The laboratory has been working around the clock, Martin says, increasing their test capacity from 5,000 COVID-19 samples to 10,000; as of today, they have tested more than 20,000 samples.
The test is authorized under the lab’s Clinical Laboratory Improvement Amendments (CLIA) license, and MicroGenDx is also seeking Emergency Use Authorization (EUA) from the FDA. Earlier this week, FDA granted emergency use authorization (EUA) to Rutgers' RUCDR Infinite Biologics and its collaborators for a new collection approach that utilizes saliva as the primary test biomaterial for the SARS-CoV-2 coronavirus.
MicroGenDX’s test is viable for self-collection because it is a provider-authorized LDT that falls under their CLIA license and is not an “at-home testing kit.” The LDT is shipped for sample collection—via sputum cup—to the patient to spit into. This is no different than sending a urine cup for a urine sample where there is no role for the provider in overseeing the sample collection, Martin explains.
Once a sample is tested, MicroGenDX sends results via web portal, where physicians can download a PDF file of the patient’s report. Martin says they also build data integration systems for larger hospitals in order to send reports back through the hospital’s electronic medical records (EMRs). Martin says this integration has been a struggle, as most hospitals are reluctant to work with labs with which they don’t have a data connection.
Despite these seemingly endless challenges, Martin says the COVID-19 has—for better or worse—increased the validity of molecular testing. “Our current situation has allowed the world to become educated in PCR [polymerase chain reaction] and molecular diagnostics,” he said. “The only way [COVID-19] is detected, besides antibody testing, is through a molecular test, and that helps us significantly. We are constantly battling, trying to make physicians understand that you don’t need to grow bacteria in a petri dish like we did in the 1870s. We can identify bacteria through its DNA—and in this case we’re identifying this virus by its RNA.”