Methods: Following the manufacturer’s instructions, we analyzed directly 40 residual patient specimens that had been frozen in virus transport medium (Meridian, Cincinnati, OH). Aliquots had previously been extracted by MagNA Pure (Roche) and reported as Simplexa positive only for Flu A (20: winter 2013-2014, presumptive H1:N1; and 20: winter 2014-2015, presumptive H3:N2) or for FluB (10: winter 2014-2015). We also included 9 frozen patient samples that had tested positive for respiratory syncytial virus (RSV) but negative for both FluA and FluB by Simplexa.
Results: Among the 40 FluA-positive specimens, one was missed by Liat: it had a crossing threshold (CT) in the Simplexa assay of 37.1, indicating a low concentration of virus. When re-extracted and re-analyzed the discordant sample remained Simplexa-positive with a similar CT. The CTs of other specimens were lower suggesting the presence of higher concentrations of virus. An alternative molecular technique detected this organism and identified it as FluA, type H3. Overall sensitivity for FluA was 97.5%: 95% for 2013-2014 and 100% for 2014-2015. Liat detected 10/10 samples that were Simplexa positive for FluB (sensitivity: 100%). Among 9 specimens reported by Simplexa as positive for RSV but negative for both FluA and FluB, none was reported as positive by Liat for either influenza virus. No dual FluA/B infection was reported by Liat. The specificities of Liat for FluA and for FluB were each 100%.
Conclusion: Liat is a good candidate for a STAT molecular test for fluA/B. It is rapid, sensitive and specific, and requires no nucleic acid extraction or specialized molecular training. The analyzer is small (footprint: 11.4 x 24 cm) and light (3.76 Kg). Results are available in about 20 min, with 1 min hands-on time. It is not presently classified as a waived test by the U.S. FDA.
BioFire: Grant Investigator , Grant recipient and Research grant
GenMark: Grant Investigator , Grant recipient and Research grant
Accelerate: Grant Investigator , Grant recipient and Research grant
AdvanDx: Grant Investigator , Grant recipient and Research grant
V. Verma-Ahuja, None
D. Prebelich, None
P. Lephart, None