Evaluation of a polymerase chain reaction–electrospray ionization time-of-flight mass spectrometry for the detection and subtyping of influenza viruses in respiratory specimens

BACKGROUND: PCR coupled to electrospray ionization mass spectrometry technology (PCR/ESI-TOF-MS) (PLEX-ID system, Abbott Ibis Biosciences) was developed to characterize microbial pathogens. OBJECTIVES: To evaluate the performance of the PLEX-ID flu detection™ kit for detecting Influenza viruses by comparison with the multiplex RespiFinder(®) Kit (PathoFinder). STUDY DESIGN: Acute-phase respiratory samples (n = 293) were analysed for this purpose. A subpopulation of influenza type A positive samples, identified with the RespiFinder(®) kit (n = 64), were subtyped with the RealTime ready Inf A/H1N1 Detection Set(®) (Roche Molecular Diagnostics) and results were compared to the PLEX-ID Flu Detection™ kit. RESULTS: 274 samples gave concordant results (93.5%, p < 0.0001): 65 influenza A-positive, 18 influenza B-positive and 191 negative samples. Of these, 7 samples were PLEX-ID positive/RespiFinder(®) negative (5 influenza A and 2 influenza B) and 12 were PLEX-ID positive/RespiFinder(®) negative (10 influenza A and 2 influenza B). PLEX-ID showed one sample as an influenza A and B co-infection while the RespiFinder(®) assay showed it to be influenza A-positive. The sensitivity, specificity, positive and negative predictive values of the PLEX-ID™ system were 87.4%, 96.5%, 92.2% and 94.1% respectively. Thirteen of 19 discordant samples available for retesting were investigated further with the Anyplex™II RV16 Detection kit (Seegene): seven were RespiFinder(®) concordant, while six were PLEX-ID™ concordant. Subtyping of 61/64 influenza A samples was concordant (95.3%): 55 were H1N1pdm09 and six were non-H1N1pdm09. Three samples gave negative PLEX-ID™ results (one H1N1pdm09 and two non-H1N1pdm09). CONCLUSIONS: PCR/ESI-TOF-MS technology showed good diagnostic performances to detect and subtype influenza viruses.