Real-time PCR compared to Binax NOW and cytospin-immunofluorescence for detection of influenza in hospitalized patients

J Clin Virol. 2008 Oct;43(2):148-51. doi: 10.1016/j.jcv.2008.06.006. Epub 2008 Jul 18.


Background: Rapid tests have had a significant impact on influenza diagnosis, but more accurate tests are needed for hospitalized patients who test negative by rapid methods.

Objective: We sought to determine the increased yield obtained from influenza RT-PCR in hospitalized patients compared to two rapid methods.

Study design: Binax NOW, cytospin-enhanced direct immunofluoroescence (DFA), and influenza A and B multiplex TaqMan RT-PCR were performed on 237 clinical samples.

Results: Binax NOW detected 70 (53.0%), cytospin-DFA detected 127 (96.2%), and TaqMan RT-PCR detected 132 (100%) influenza-positive samples. The difference in sensitivity was significant between RT-PCR and Binax NOW (p<0.0001), but not between RT-PCR and cytospin-DFA (p=0.0736). Two samples testing positive for influenza B by all three methods, tested falsely positive for influenza A by Binax. Eight true positive samples did not become reactive by Binax until 30 min, and thus were counted as negative.

Conclusions: The accuracy of real-time RT-PCR should greatly improve the diagnosis of influenza in hospitals using simple rapid flu tests, but may have a more modest impact in hospitals with expertise in cytospin-DFA. Further studies are needed to determine the effect of influenza RT-PCR on patient management and costs in hospitalized patients.

Publication types

  • Comparative Study
  • Evaluation Study

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Antibodies, Monoclonal / immunology
  • Child
  • Child, Preschool
  • Fluorescent Antibody Technique, Direct / methods*
  • Hospitalization
  • Humans
  • Immunoassay / methods
  • Infant
  • Influenza A virus* / genetics
  • Influenza A virus* / immunology
  • Influenza A virus* / isolation & purification
  • Influenza B virus* / genetics
  • Influenza B virus* / immunology
  • Influenza B virus* / isolation & purification
  • Influenza, Human / diagnosis*
  • Influenza, Human / virology
  • Middle Aged
  • Nasopharynx / virology
  • Reagent Kits, Diagnostic*
  • Reproducibility of Results
  • Reverse Transcriptase Polymerase Chain Reaction / methods*
  • Sensitivity and Specificity
  • Taq Polymerase
  • Time Factors
  • Virus Cultivation
  • Young Adult


  • Antibodies, Monoclonal
  • Reagent Kits, Diagnostic
  • Taq Polymerase