Abstract
BackgroundClinical signs and symptoms of different airway pathogens are generally indistinguishable, making laboratory tests essential for clinical decisions regarding isolation and antiviral therapy. Immunochromatographic tests (ICT) and direct immunofluorescence assays (DFA) have lower sensitivities and specificities than molecular assays, but have the advantage of quick turnaround times and ease-of-use. ObjectiveTo evaluate the performance of a rapid molecular assay, ARIES FluA/B & RSV, using laboratory developed RT-PCR assays (LDA), ICT (BinaxNOW) and DFA. MethodsAnalytical and clinical performance were evaluated in a retrospective study arm (stored respiratory samples obtained between 2006–2015) and a prospective study arm (unselected fresh clinical samples obtained between December 2015 and March 2016 tested in parallel with LDAs). ResultsGenotype inclusivity and analytical specificity was 100%. However, ARIES was 0.5 log, 1–2logs and 2.5logs less sensitive for fluA, RSV and fluB respectively, compared to LDA. In total, 447 clinical samples were included, of which 15.4% tested positive for fluA, 9.2% for fluB and 26.0% for RSV, in both LDA and ARIES. ARIES clinical sensitivity compared to LDA was 98.6% (fluA), 93.3% (fluB) and 95.1% (RSV). Clinical specificity was 100% for all targets. ARIES detected 10.6% (4 fluA, 8 fluB, 11 RSV) and 26.9% (7 fluA, 3 fluB, 22 RSV) more samples compared to DFA and ICT, all confirmed by LDA. ConclusionAlthough analytically ARIES is less sensitive than LDA, the clinical performance of the assay in our tertiary care setting was comparable, and significantly better than that of the established rapid assays.
Highlights
Clinical signs and symptoms of different airway pathogens are generally indistinguishable, making laboratory tests essential for clinical decisions regarding isolation and antiviral therapy
To determine the repeatability, %CV was calculated of 37 replicates of a positive process control (PPC) containing each fluA, fluB and RSVA/B viruses, resulting in a%CV of 2.7–3.6%
The concentration of fluB (LDA Ct-value 26.4) in the PPC was close to the ARIES limit of detection and tested positive 32 out of 37 (86.5%), fluA (LDA Ct-value 27.5) and respiratory syncytial virus (RSV) (LDA Ct-value RSVA 25.1, RSVB 26.4) tested positive in all replicates
Summary
Clinical signs and symptoms of different airway pathogens are generally indistinguishable, making laboratory tests essential for clinical decisions regarding isolation and antiviral therapy. Immunochromatographic tests (ICT) and direct immunofluorescence assays (DFA) have lower sensitivities and specificities than molecular assays, but have the advantage of quick turnaround times and ease-of-use. Objective: To evaluate the performance of a rapid molecular assay, ARIES FluA/B & RSV, using laboratory developed RT-PCR assays (LDA), ICT (BinaxNOW) and DFA. Conclusion: analytically ARIES is less sensitive than LDA, the clinical performance of the assay in our tertiary care setting was comparable, and significantly better than that of the established rapid assays. Rapid and accurate detection of influenza A (fluA) and B (fluB) viruses and respiratory syncytial virus (RSV) is important for clinical patient management and infection control purposes. Like direct immunofluorescence assays (DFA) or immunochromatographic tests (ICT) have quick turnaround times, but are less sensitive and less specific compared to molecular assays
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