title: Bacterial rapid identification with matrix assisted laser desorption/ionization time-of-flight mass spectrometry: development of an 'in-house method' and comparison with Bruker Sepsityper(®) kit.
abstract: OBJECTIVE
  The objective of this study was to compare an in-house matrix-assisted laser desorption ionization with time of flight (MALDI-TOF) method and a commercial MALDI-TOF kit (Sepsityper(®) kit) for direct bacterial identification in positive blood cultures. We also evaluated the time saved and the cost associated with the rapid identification techniques.
  
  
  METHODS
  We used the BACTEC(®) automated system for detecting positive blood cultures. Direct identification using Sepsityper kit and the in-house method were compared with conventional identification by MALDI-TOF using pure bacterial culture on the solid phase. We also evaluated different cut-off scores for rapid bacterial identification.
  
  
  RESULTS
  In total, 127 positive blood vials were selected. The rate of rapid identification with the MALDI Sepsityper kit was 25.2% with the standard cut-off and 33.9% with the enlarged cut-off, while the results for the in-house method were 44.1 and 61.4%, respectively. Error rates with the enlarged cut-off were 6.98 (n = 3) and 2.56% (n = 2) for Sepsityper and the in-house method, respectively. Identification rates were higher for gram-negative bacteria.
  
  
  CONCLUSIONS
  Direct bacterial identification succeeded in supplying rapid identification of the causative organism in cases of sepsis. The time taken to obtain a result was nearly 24  hours shorter for the direct bacterial identification methods than for conventional MALDI-TOF on solid phase culture. Compared with the Sepsityper kit, the in-house method offered better results and fewer errors, was more cost-effective and easier to use.
authors.affiliation: Trainee in Laboratory Medicine, Université Catholique de Louvain , Belgique.
authors.forename: S
authors.initials: S
authors.lastname: Frédéric Ric
authors.forename: M
authors.initials: M
authors.lastname: Antoine
authors.forename: A
authors.initials: A
authors.lastname: Bodson
authors.forename: B
authors.initials: B
authors.lastname: Lissoir
mesh_terms: D016470:Bacteremia / Q000382:microbiology*; D001431:Bacteriological Techniques; D006090:Gram-Negative Bacteria / Q000302:isolation & purification*; D006094:Gram-Positive Bacteria / Q000302:isolation & purification*; D006801:Humans; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*
keywords: Bacteria; Bacterial; Bacteriology; Direct identification; MALDI-TOF; Matrix-assisted laser desorption ionization; Medical laboratory; Microbiology; Rapid identification; Sepsityper