Evaluation of an automated multiplex real-time RT-PCR assay for rapid detection of Influenza A and B viruses

Sammanfattning: Influenza is a viral infection that affects global health and economy with its endemic and sometimes pandemic spread. Rapid detection of Influenza viruses enables antiviral use and can bring financial savings. It is also essential for the global surveillance of prevalent Influenza strains. RT-PCR is considered the most specific and sensitive method for detection of Influenza, but Influenza mutates at a high rate and it is therefore crucial that RT-PCR methods are updated regularly. In 2014, Cepheid released their Xpert Flu/RSV XC assay, which can detect Influenza A and B and RSV by multiplex RT-PCR in approximately one hour. The aim of this study was to evaluate this assay at Laboratoriemedicin Västernorrland by using the laboratory’s previous PCR assay for detection of Influenza viruses as reference method. Real-time RT-PCR was used to compare Xpert Flu/RSV XC to the reference method. A dilution series was performed to estimate the methods’ PCR efficiencies and precision was calculated from quadruplicates of a positive control sample. Clinical specimens (n=42) were used to evaluate the diagnostic sensitivity and specificity of Xpert Flu/RSV XC. Objective statistical analysis of PCR data was performed and discussed. The Xpert Flu/RSV XC was equivalent to the reference method and demonstrated high diagnostic sensitivity and specificity. Estimated PCR efficiencies were however low. With the introduction of Xpert Flu/RSV XC to the laboratory follows many potential benefits, primarily in form of a simplified pre analytical procedure and a shortened analysis time. The Xpert Flu/RSV XC assay enables fast diagnosis of Influenza infection.