Successful use of shell vial centrifugation and 16 to 18-hour immunofluorescent staining for the detection of influenza A and B in clinical specimens.

The rapid diagnosis of influenza A and B infections is beneficial for the proper management of patients with acute respiratory illness. The authors evaluated a shell vial centrifugation method to detect these viruses 16-18 hours postinoculation and compared it with conventional tube cell culture. Rhesus monkey kidney cells were used in both methods. Conventional culture of 334 respiratory specimens recovered 64 influenza isolates; the average time to positivity was 4.1 days. Low-speed shell vial centrifugation with polyclonal immunofluorescent staining 16-18 hours postinoculation was performed on 96 fresh specimens and on an additional 38 frozen specimens. These 134 specimens contained 49 of the 64 total influenza-positive specimens. The shell vial method yielded a sensitivity of 90.9% and 87.5% for fresh and frozen specimens, respectively, as compared with conventional tube cell culture. The authors conclude that the shell vial method is an important adjunct to conventional culture for the rapid detection of influenza A and B in clinical specimens.