title: Performance evaluation of direct fluorescent antibody, Focus Diagnostics Simplexa™ Flu A/B & RSV and multi-parameter customized respiratory Taqman® array card in immunocompromised patients.
abstract: Molecular assays for diagnosis of Flu A, Flu B, and RSV with short turn-around-time (TAT) are of considerable clinical importance. In addition, rapid and accurate diagnosis of a large panel of viral and atypical pathogens can be crucial in immunocompromised patients.
  
  
  
  First, to evaluate the performance of the Simplexa™ Direct assay system in comparison with direct fluorescent antibody (DFA) and customized Taqman® Array Card (TAC) testing for RSV, Flu A, and Flu B in immunocompromised patients. Second, to evaluate different algorithms for the detection of respiratory pathogens in terms of cost, turn-around-time (TAT) and diagnostic yield.
  
  
  
  We collected 125 nasopharyngeal swabs (NTS) and 25 BAL samples from symptomatic immunocompromised patients. Samples for which Simplexa™ and TAC results were discordant underwent verification testing. The TAC assay is based on singleplex RT-PCR, targeting 24 viruses, 8 bacteria and 2 fungi simultaneously.
  
  
  
  The overall sensitivity was significantly lower for DFA testing than for the two molecular methods (p<0.05). Performance characteristics of Simplexa™ testing were not significantly different compared to TAC testing (p>0.1). For BAL samples only, the sensitivity and specificity of the Simplexa™ assay was 100%. In total, 6.7, 16 and 18% of samples were positive for Flu A, Flu B or RSV by DFA, Simplexa™ and TAC testing, respectively. When considering not only these pathogens but also all results for TAC, the method identified 93 samples with one or more respiratory pathogens (62%). A co-infection rate of 15.3% was found by TAC. The estimated costs and TAT were 8.2€ and 2h for DFA, 31.8€ and 1.5h for Simplexa™ and 55€ and 3h for TAC testing.
  
  
  
  Performing the Simplexa™ test 24h a day/7 days a week instead of DFA would considerably improve the overall sensitivity and time-to-result, albeit at a higher cost generated in the laboratory. Performing the TAC would increase the diagnostic yield and detection of co-infections significantly.
authors.affiliation: Department of Clinical Microbiology, CUB-Erasme, Université Libre de Bruxelles, Brussels, Belgium. Electronic address: deborah.steensels@erasme.ulb.ac.be.
authors.forename: Deborah
authors.initials: D
authors.lastname: Steensels
authors.affiliation: Department of Clinical Microbiology, AZ St-Jan Brugge-Oostende Hospital, Brugge, Belgium.
authors.forename: Marijke
authors.initials: M
authors.lastname: Reynders
authors.affiliation: Department of Clinical Microbiology, AZ St-Jan Brugge-Oostende Hospital, Brugge, Belgium.
authors.forename: Patrick
authors.initials: P
authors.lastname: Descheemaeker
authors.affiliation: Public Health England, Clinical Microbiology and Public Health Laboratory, Addenbrooke's Hospital, Cambridge, UK.
authors.forename: Martin D
authors.initials: MD
authors.lastname: Curran
authors.affiliation: Department of Infectious Diseases, CUB-Erasme, Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: Frédérique
authors.initials: F
authors.lastname: Jacobs
authors.affiliation: Department of Clinical Microbiology, CUB-Erasme, Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: Olivier
authors.initials: O
authors.lastname: Denis
authors.affiliation: Department of Clinical Microbiology, CUB-Erasme, Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: Marie-Luce
authors.initials: ML
authors.lastname: Delforge
authors.affiliation: Department of Clinical Microbiology, CUB-Erasme, Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: Isabel
authors.initials: I
authors.lastname: Montesinos
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D001992:Bronchoalveolar Lavage Fluid / Q000821:virology; D060085:Coinfection / Q000175:diagnosis* / Q000821:virology; D005260:Female; D019085:Fluorescent Antibody Technique, Direct / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D006801:Humans; D016867:Immunocompromised Host; D007251:Influenza, Human / Q000175:diagnosis* / Q000821:virology; D008297:Male; D046228:Microarray Analysis / Q000379:methods / Q000592:standards; D008875:Middle Aged; D025202:Molecular Diagnostic Techniques / Q000191:economics / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D009305:Nasopharynx / Q000821:virology; D060888:Real-Time Polymerase Chain Reaction / Q000295:instrumentation / Q000379:methods*; D018357:Respiratory Syncytial Virus Infections / Q000175:diagnosis* / Q000821:virology; D012680:Sensitivity and Specificity; D055815:Young Adult
keywords: Flu A; Flu B and RSV molecular detection; Immunocompromised patients; Simplexa; Taqman array card