title: Evaluation of matrix-assisted laser desorption ionization-time of flight mass spectrometry-based VITEK MS system for the identification of Acinetobacter species from blood cultures: comparison with VITEK 2 and MicroScan systems.
abstract: BACKGROUND
  Acinetobacter species are the leading cause of bloodstream infection (BSI), but their correct identification is challenging. We evaluated the matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS)-based VITEK MS (bioMérieux, France), and two automated systems, VITEK 2 (bioMérieux) and MicroScan (Siemens, USA) for identification of Acinetobacter BSI isolates.
  
  
  METHODS
  A total of 187 BSI isolates recovered at a university hospital in Korea between 2010 and 2012 were analyzed. The identification results obtained using VITEK MS and two automated systems were compared with those of rpoB sequencing.
  
  
  RESULTS
  Of 187 isolates analyzed, 176 were identified to the species level by rpoB sequencing: the Acinetobacter baumannii group (ABG; 101 A. baumannii, 43 A. nosocomialis, 10 A. pittii isolates) was most commonly identified (82.4%), followed by Acinetobacter genomic species 13BJ/14TU (5.3%), A. ursingii (2.1%), A. soli (2.1%), A. bereziniae (1.1%), and A. junii (1.1%). Correct identification rates to the species group (ABG) level or the species level was comparable among the three systems (VITEK MS, 90.3%; VITEK 2, 89.2%; MicroScan, 86.9%). However, VITEK MS generated fewer misidentifications (0.6%) than VITEK 2 (10.8%) and MicroScan (13.1%) (P<0.001). In addition, VITEK MS demonstrated higher specificity (100%) for discrimination between ABG and non-ABG isolates than the other systems (both, 31.8%) (P<0.001).
  
  
  CONCLUSIONS
  The VITEK MS system is superior to the VITEK 2 and MicroScan systems for identification of Acinetobacter BSI isolates, with fewer misidentifications and better discrimination between the ABG and non-ABG isolates.
authors.affiliation: Department of Laboratory Medicine, Chonnam National University Medical School, Gwangju, Korea.
authors.forename: Seung Yeob
authors.initials: SY
authors.lastname: Lee
authors.affiliation: Department of Laboratory Medicine, Chonnam National University Medical School, Gwangju, Korea.
authors.forename: Jong Hee
authors.initials: JH
authors.lastname: Shin
authors.affiliation: Department of Laboratory Medicine, Chonnam National University Medical School, Gwangju, Korea.
authors.forename: Soo Hyun
authors.initials: SH
authors.lastname: Kim
authors.affiliation: Department of Laboratory Medicine, Chonnam National University Medical School, Gwangju, Korea.
authors.forename: Myung Geun
authors.initials: MG
authors.lastname: Shin
authors.affiliation: Department of Laboratory Medicine, Chonnam National University Medical School, Gwangju, Korea.
authors.forename: Soon Pal
authors.initials: SP
authors.lastname: Suh
authors.affiliation: Department of Laboratory Medicine, Chonnam National University Medical School, Gwangju, Korea.
authors.forename: Dong Wook
authors.initials: DW
authors.lastname: Ryang
mesh_terms: D000150:Acinetobacter / Q000235:genetics* / Q000302:isolation & purification; D000151:Acinetobacter Infections / Q000175:diagnosis / Q000382:microbiology; D001426:Bacterial Proteins / Q000235:genetics; D015373:Bacterial Typing Techniques / Q000295:instrumentation* / Q000379:methods*; D001769:Blood / Q000382:microbiology*; D004269:DNA, Bacterial / Q000032:analysis* / Q000378:metabolism; D030541:Databases, Genetic; D006801:Humans; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial
keywords: Acinetobacter; Identification; MicroScan; VITEK 2; VITEK MS