Direct Comparison of Alere i and cobas Liat Influenza A and B Tests for Rapid Detection of Influenza Virus Infection

Abstract

We compared two rapid, point-of care nucleic acid amplification tests for detection of influenza A and B viruses (Alere i [Alere] and cobas Liat [Roche Diagnostics]) with the influenza A and B virus test components of the FilmArray respiratory panel (BioFire Diagnostics) using 129 respiratory specimens collected in universal viral transport medium (80 influenza A virus and 16 influenza B virus positive) from both adult and pediatric patients. The sensitivities of the Alere test were 71.3% for influenza A virus and 93.3% for influenza B virus, with specificities of 100% for both viruses. The sensitivities and specificities of the Liat test were 100% for both influenza A and B viruses. The poor sensitivity of the Alere test for detection of influenza A virus was likely due to a study set that included many low-positive samples that were below its limit of detection. Influenza is a significant cause of morbidity and mortality worldwide. Although the diagnosis is often made by clinical signs and symptoms alone, laboratory testing may be needed to guide antiviral therapy, determine isolation precautions, and provide epidemiologic data, since many different respiratory viruses can cause influenza-like illness. The laboratory diagnosis of influenza has evolved from the use of culture and antigen detection tests to nucleic acid amplification tests that are now considered the new gold standard.Until recently, point-of-care diagnostic testing has been limited to rapid antigen tests based on chromatographic immunoassay technology designed in simple-to-use formats with results available in Ͻ30 min. The chromatographic immunoassays typically have suffered from moderate to low sensitivity; however, recent improvements in test chemistries and instrument readout of results have improved their performance characteristics (1-4). Currently, there are two CLIA-waived, FDA-cleared nucleic acid amplification tests designed to be performed as point-of-care tests by nonlaboratory personnel, the Alere i (Alere, Scarborough, MA) and cobas Liat (Roche Diagnostics, Indianapolis IN) influenza A and B tests. These tests hold promise to significantly improve near-patient diagnostic testing for influenza and may facilitate true practice changes in how clinicians manage these patients.The Alere test is semiautomated and uses an isothermal nicking enzyme amplification reaction and fluorescently labeled molecular beacons to amplify and detect a region of the polymerase basic protein 2 gene in influenza A virus, a region of the polymerase acid protein gene in influenza B virus, and an internal control in less than 15 min (5). The Alere test is intended to be used for direct nasal swabs (CLIA complexity, waived) and for nasal and nasopharyngeal swabs eluted in viral transport medium (CLIA complexity, moderate). The Alere test has reported sensitivities and specificities of from 80 to 99.3% and from 62.5 to 100%, respectively, for detection of influenza A virus and from 45.2 to 97.6% and 53.6 to 100%, respectively, for detection of influenza B vir...

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