SARS-COV-2 assay for screening stool donors for FMT protocols.

Every year, over 400,000 people in the U.S. suffer chronic diarrhea and colon inflammation caused by the invasive bacterium Clostridioides difficile, an infection commonly associated with taking antibiotics and being hospitalized. C. diff. infection can be quite difficult to manage, even deadly. In the last decade, fecal microbiota transplants (FMT), AKA stool transplants, emerged as an effective treatment. Stool for FMT is provided by healthy people who serve as donors. To avoid trading one problem for another, FDA has put procedures in place to screen stool for a variety of microbes, minimizing the chances that FMT will inadvertently introduce another infection. When COVID-19 burst into the world in 2019, scientists quickly realized that the SARS-CoV-2 virus was shed into stool. This raised the possibility of transmitting SARS-CoV-2 through FMT and prompted the need for additional donor screening. FDA quickly issued a safety alert and contacted health care providers to describe the issue.

CBER researchers, who are reviewers that regulate FMT products, quickly recognized this new risk and headed to the lab to find a solution. They modified a nasal SARS-CoV-2 testing protocol for use with stool, and then they characterized the test to see how it worked in practical situations. Studies established the test’s good sensitivity and its reliable performance following storage of stool under various conditions. Researchers then applied the test method to stool samples from people with COVID-19 symptoms who were diagnosed as SARS-CoV-2+ by standard nasal swab PCR. The result? The new test successfully detected SARS-CoV-2 RNA in the stool of about 50% of these people, laying the groundwork – very early in the pandemic – for new donor stool screening and more assurance of FMT safety. Screening of stool donors for SARS-CoV-2 remains a high priority, even in the era of vaccines.