Practical recommendations for the detection of pediatric respiratory syncytial virus infections.

In our private clinic-hospital setting, respiratory syncytial virus (RSV) was isolated from infants more frequently and sooner from nasal washes (84%; 4.2 days) than from throat swabs (45%; 5.5 days) or nasopharyngeal swabs (39%; 5.7 days). Immunofluorescence of nasal wash cells identified 72% of the infants with virus isolations from nasal washes in less than one day. We therefore recommend the combination of isolation and immunofluorescence on nasal wash specimens for optimal detection of RSV-infected infants. Immunofluorescence of respiratory tract cells was also useful for monitoring the presence of RSV antigen in intubation secretions during ribavirin antiviral therapy. RSV infectivity was maintained in phosphate-buffered saline at room temperature for 6 h. Transport and inoculation of specimens in less than 6 h yielded RSV isolates from 50% of sampled infants during the two RSV seasons examined. For optimal RSV isolation, we recommend inoculation of HEp-2 tubes less than or equal to 4 days old. Replacing medium after 3 days as compared with 7 days did not increase recovery of RSV and provided little practical reduction in time to detection of cytopathology.