Comparison of VIDAS with direct immunofluorescence for the detection of respiratory syncytial virus in clinical specimens.

BACKGROUND: requirements for infection control measures and the decision for treatment with antiviral agents make the rapid detection of respiratory syncytial virus (RSV) essential for hospitalized, pediatric and immunocompromised patients. Immunofluorescence is considered to be the most rapid and sensitive method for direct detection of RSV in clinical specimens, but several enzyme-linked immunoassays have also been commercially available. OBJECTIVES: to compare the performance of VIDAS RSV assay (Vitek ImmunoDiagnostic Assay System, BioMerieux Vitek), which is an automated enzyme-linked fluorescent immunoassay (ELFA) to direct immunofluorescence (DFA), in rapid detection of RSV in respiratory specimens. STUDY DESIGN: respiratory specimens collected during the 'RSV season', between the months of November 1997 and February 1998, were tested by both methods. DFA was performed upon receipt of the sample and an aliquot of the original specimen was stored in -70 degrees C for batch testing with VIDAS. RESULTS: from 238 samples that were tested, 231 could be evaluated by both methods. The two assays were in agreement for 213 specimens (92%), or 32 positive and 181 negative results. Eighteen discrepant results were generated; seven specimens were VIDAS-/DFA+ and 11 specimens were VIDAS+/DFA-. In addition, seven specimens had an inadequate number of cells for evaluation with DFA. One of these samples tested positive with VIDAS. VIDAS relative sensitivity and specificity were 82% and 94%, respectively, when compared to DFA. CONCLUSIONS: VIDAS is simple to perform, does not require expertise in interpretation and appears to be an acceptable method for the rapid detection of RSV.