Comparison of cell culture and three enzyme-linked immunosorbent assays for the rapid diagnosis of respiratory syncytial virus from nasopharyngeal aspirate and tracheal secretion specimens

Abstract

A total of 211 specimens, including 144 nasopharyngeal aspirates and 67 tracheal secretions, were evaluated for the rapid detection of Respiratory Syncytial Virus (RSV) antigen by three commercial enzyme-linked immunosorbent assays (ELISA; Kallestad Diagnostic, Austin, TX; Ortho Diagnostics, Raritan, NJ, and Abbott Laboratories, North Chicago, IL) and by isolation of RSV in cell culture. Of the 61 RSV culture positive specimens, Kallestad ELISA, Ortho ELISA, and Abbott ELISA detected RSV antigen in 80%, 95%, and 92% of the specimens, respectively. An additional 28 specimens were found to be positive only by one or more RSV ELISA tests. A blocking assay confirmed the specificity of ELISA in 71% (20/28) of the RSV ELISA positive and the culture-negative specimens, and 29% were found to be false positive. Through the use of cell culture, with the resolution of ELISA positive and culture negative specimens by blocking assay, 81 specimens (61 + 20) were considered to be true positive. The sensitivity, specificity, and diagnostic accuracy were, for cell culture, 75%, 100%, and 91%; for Kallestad ELISA, 79%, 98%, and 91%; for Ortho ELISA, 95%, 99%, and 98%; and for Abbott ELISA, 93%, 96%, and 95% respectively. In our study, commercial ELISA tests have been shown to be rapid, reliable tests for the detection of RSV. Ortho ELISA and Abbott ELISA showed better sensitivity than the Kallestad ELISA for RSV detection directly in the clinical specimens.