title: Comparison of the performance of direct fluorescent antibody staining, a point-of-care rapid antigen test and virus isolation with that of RT-PCR for the detection of novel 2009 influenza A (H1N1) virus in respiratory specimens.
abstract: Although infections with the novel pandemic 2009 influenza A (H1N1) virus (A/H1N1/2009) appeared to be relatively mild during the first summer of circulation ('off season'), there has been significant morbidity and hospitalization and several fatal cases. Thus, rapid detection of A/H1N1/2009 is crucial for efficient treatment and infection control measures. In contrast to seasonal influenza, where point-of-care (POC) rapid antigen tests and direct fluorescent antibody (DFA) staining ensure rapid detection, diagnosis of A/H1N1/2009 has so far been based on RT-PCR. This study retrospectively compared the performance of the Quidel QuickVue POC test, DFA staining and virus isolation with that of RT-PCR for A/H1N1/2009 detection in 526 respiratory specimens collected during the first wave of the outbreak from May to September 2009. A/H1N1/2009 was detected in 9.1% (48/526) of samples. One hundred and thirty-seven of the A/H1N1/2009 PCR-negative samples were additionally tested using a RealAccurate Respiratory RT-PCR panel, revealing other respiratory viruses (mainly entero/rhino- and adenoviruses) in 42.3% (58/137). All methods analysed detected A/H1N1/2009 with excellent specificity but different sensitivities (POC test: 18.2%; DFA staining: 38.7%; virus isolation: 45.7%). Therefore, the POC test was not suitable for diagnosis, detecting A/H1N1/2009 only if present in high concentrations (corresponding median Ct value=19.0; range=16.5-21.4). DFA staining was also able to detect A/H1N1/2009 in specimens with a lower virus concentration (median Ct value=24.0; range=16.5-29.8). Virus isolation, which was positive after a median time of 7.5 days, was too time-consuming. In summary, DFA staining is superior to POC testing and may be appropriate for patients expected to have a rather high level of virus replication. Nevertheless, in DFA-negative specimens, A/H1N1/2009 should be excluded by RT-PCR.
authors.affiliation: Institute of Virology, Hannover Medical School, Carl-Neuberg-Straße 1, 30625 Hannover, Germany.
authors.forename: Tina
authors.initials: T
authors.lastname: Ganzenmueller
authors.affiliation: Institute of Virology, Hannover Medical School, Carl-Neuberg-Straße 1, 30625 Hannover, Germany.
authors.forename: Jeanette
authors.initials: J
authors.lastname: Kluba
authors.affiliation: Institute of Virology, Hannover Medical School, Carl-Neuberg-Straße 1, 30625 Hannover, Germany.
authors.forename: Birgit
authors.initials: B
authors.lastname: Hilfrich
authors.affiliation: Institute of Virology, Hannover Medical School, Carl-Neuberg-Straße 1, 30625 Hannover, Germany.
authors.forename: Wolfram
authors.initials: W
authors.lastname: Puppe
authors.affiliation: Institute of Virology, Hannover Medical School, Carl-Neuberg-Straße 1, 30625 Hannover, Germany.
authors.forename: Willem
authors.initials: W
authors.lastname: Verhagen
authors.affiliation: Institute of Virology, Hannover Medical School, Carl-Neuberg-Straße 1, 30625 Hannover, Germany.
authors.forename: Albert
authors.initials: A
authors.lastname: Heim
authors.affiliation: Institute of Virology, Hannover Medical School, Carl-Neuberg-Straße 1, 30625 Hannover, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Schulz
authors.affiliation: Institute of Virology, Hannover Medical School, Carl-Neuberg-Straße 1, 30625 Hannover, Germany.
authors.forename: Cornelia
authors.initials: C
authors.lastname: Henke-Gendo
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000379:methods; D007223:Infant; D007231:Infant, Newborn; D053118:Influenza A Virus, H1N1 Subtype / Q000235:genetics / Q000254:growth & development / Q000276:immunology / Q000302:isolation & purification*; D007251:Influenza, Human / Q000175:diagnosis* / Q000821:virology*; D008297:Male; D008875:Middle Aged; D019095:Point-of-Care Systems; D012189:Retrospective Studies; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity; D014773:Virology / Q000379:methods*; D055815:Young Adult