Comparison of two enzyme-linked immunosorbent assay (EIA) kits with immunofluorescence and isolation in cell culture for detection of respiratory syncytial virus (RSV).

Rapid diagnosis of respiratory syncytial virus (RSV) infections is based upon detection of viral antigen in cells obtained from the respiratory tract and usually employs immunofluorescence (IF) reactions or enzyme-linked immunosorbent assays (EIA). The Pathfinder EIA kit (Kallestad Diagnostics) was compared with the Abbott EIA kit by evaluating each against isolation of RSV in cell culture and detection of antigen by IF. The Pathfinder kit identified 116 of 129 culture-positive and 72 of 90 culture-negative specimens; the sensitivity was 90 percent and the specificity was 80 percent. The sensitivity of the Abbott EIA test compared to isolation of RSV in cell culture was 91% (115 of 127), and the specificity was 83% (74 of 89). Of 165 specimens evaluated by IF, the Pathfinder kit detected 97 of 105 IF-positive and 45 of 60 IF-negative specimens, giving a sensitivity of 92% and a specificity of 75%. The Abbott EIA compared similarly with IF, showing a sensitivity of 91% (98 of 108) and a specificity (42 of 54) of 78%. Visual reading of the Kallestad test resulted in a sensitivity of 92%, a specificity of 91%, positive predictive value of 95%, and negative predictive value of 86%. The Pathfinder EIA kit compared well with IF and the Abbott EIA for detection of RSV antigen but performed faster than the Abbott test and offers the option of a visual reading.