Comparison of BD Directigen EZ RSV and Binax NOW RSV tests for rapid detection of respiratory syncytial virus from nasopharyngeal aspirates in a pediatric population.

The BD Directigen EZ RSV (BD) assay and the Binax NOW RSV (BN) assays are lateral flow immunochromatographic assays used in the rapid diagnosis of respiratory syncytial virus (RSV) infection. A prospective study was undertaken to compare the performance characteristics of the BD and BN assays using 99 fresh nasopharyngeal aspirate specimens from children. All specimens were cultured by tube cultures and R-mix shell vials. Culture-negative specimens that tested positive by 1 or both antigen tests were analyzed by reverse transcriptase polymerase chain reaction (RT-PCR) for the presence of RSV nucleic acids. Specimens positive by culture and/or RT-PCR were considered true positives. The sensitivity, specificity, positive predictive value, and negative predictive value for BD were 90%, 94%, 94%, and 90%, respectively, and those for BN were 90%, 100%, 100%, and 90% respectively. The overall agreement between the 2 assays was 93% (confidence interval, 86.3-96.6%). Three specimens negative by both assays were positive by viral culture. The rapid lateral flow immunochromatographic assays were easy to perform and easy to interpret, and the results are available in less than 30 min. The reduced turnaround time offered by these assays is particularly useful in the rapid detection of RSV infections in children from outpatient settings.