A Rapid Host Response Blood Test for Bacterial/Viral Infection Discrimination Using a Portable Molecular Diagnostic Platform.

Background: Difficulty discriminating bacterial versus viral etiologies of infection drives unwarranted antibacterial prescriptions and, therefore, antibacterial resistance. Methods: Utilizing a rapid portable test that measures peripheral blood host gene expression to discriminate bacterial and viral etiologies of infection (the HR-B/V assay on Biomeme's polymerase chain reaction-based Franklin platform), we tested 3 cohorts of subjects with suspected infection: the HR-B/V training cohort, the HR-B/V technical correlation cohort, and a coronavirus disease 2019 cohort. Results: The Biomeme HR-B/V test showed very good performance at discriminating bacterial and viral infections, with a bacterial model accuracy of 84.5% (95% confidence interval [CI], 80.8%-87.5%), positive percent agreement (PPA) of 88.5% (95% CI, 81.3%-93.2%), negative percent agreement (NPA) of 83.1% (95% CI, 78.7%-86.7%), positive predictive value of 64.1% (95% CI, 56.3%-71.2%), and negative predictive value of 95.5% (95% CI, 92.4%-97.3%). The test showed excellent agreement with a previously developed BioFire HR-B/V test, with 100% (95% CI, 85.7%-100.0%) PPA and 94.9% (95% CI, 86.1%-98.3%) NPA for bacterial infection, and 100% (95% CI, 93.9%-100.0%) PPA and 100% (95% CI, 85.7%-100.0%) NPA for viral infection. Among subjects with acute severe acute respiratory syndrome coronavirus 2 infection of ≤7 days, accuracy was 93.3% (95% CI, 78.7%-98.2%) for 30 outpatients and 75.9% (95% CI, 57.9%-87.8%) for 29 inpatients. Conclusions: The Biomeme HR-B/V test is a rapid, portable test with high performance at identifying patients unlikely to have bacterial infection, offering a promising antibiotic stewardship strategy that could be deployed as a portable, laboratory-based test.