Prospective evaluation of a commercial enzyme immunoassay for the rapid antigenic detection of influenza A and B virus from paediatric respiratory samples in five consecutive influenza epidemics seasons
Abstract number: 1733_943
Reina J., Ruiz de Gopegui E., Mena A., Macia M.
Objectives: We report a prospective study of the efficacy of a commercial enzymoimmunoassay (EIA) compared with the shell-vial culture method (MDCK cell line) in the rapid antigen detection of Influenza A (IA) and Influenza B (IB) viruses in the respiratory samples of paediatric patients obtained in five consecutive flu seasons (20002005).
Material and Methods: Each of the respiratory samples (nasopharyngeal aspirates) was subjected to antigen detection against IA and IB viruses using the rapid differential EIA membrane test (Directigen FluA+B, Becton & Dickinson Co., Sparks Maryland, USA) following the manufacturer's recommendations. At the same time each sample was inoculated in two shell vials of the MDCK cell line, incubated at 36°C for 3 days and stained with specific monoclonal antibodies against each virus (Monofluokit Influenza A and B, Sanofi Diagnostics, France).
Results: In this period we studied 1,077 samples (30.8% were considered as positive) and we isolated 331 influenza viruses (234 IA, 70.7% and 97 IB, 29.3%) (p < 0.05). The percentage of influenza viruses isolated in the different epidemic periods varies significatily. The overall data of EIA method compared with the shell-vial culture show for the overall antigenic assay (IA + IB) a sensitivity of 65.8%, specificity 100%, positive predictive value 100% and negative predictive value 86.8%. There were no stastically significant differences between the overall sensitivity values (62.4% vs 74.2%) nor between the negative predictive values (89.4% vs 96.7%) for the IA and IB viruses. Statistically significant differences were observed only in the sensitivity values for the IA and IB viruses in the 20002001 (18 IA and 4 IB isolates) and 20012002 (50 IA and 20 IB isolates) seasons. We detected higher overall sensitivity overall values for the detection of IB viruses than for IA viruses. In the 20032004 season we only isolated IA viruses (29.7% of positivity).
Conclusions: In spite of the low overall sensitivity of the commercial EIA method studied, it must be regarded as an acceptable (high specificity), simple and rapid method for use in the antigenic detection of IA and IB viruses in paediatric respiratory samples.
|Session name:||European Society of Clinical Microbiology and Infectious Diseases|
|Location:||ICC, Munich, Germany|
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