title: Early identification of microorganisms in blood culture prior to the detection of a positive signal in the BACTEC FX system using matrix-assisted laser desorption/ionization-time of flight mass spectrometry.
abstract: BACKGROUND
  Matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) is a valuable method for rapid identification of blood stream infection (BSI) pathogens. Integration of MALDI-TOF MS and blood culture system can speed the identification of causative BSI microorganisms.
  
  
  METHODS
  We investigated the minimal microorganism concentrations of common BSI pathogens required for positive blood culture using BACTEC FX and for positive identification using MALDI-TOF MS. The time to detection with positive BACTEC FX and minimal incubation time with positive MALDI-TOF MS identification were determined for earlier identification of common BSI pathogens.
  
  
  RESULTS
  The minimal microorganism concentrations required for positive blood culture using BACTEC FX were >10(7)-10(8) colony forming units/mL for most of the BSI pathogens. The minimal microorganism concentrations required for identification using MALDI-TOF MS were > 10(7) colony forming units/mL. Using simulated BSI models, one can obtain enough bacterial concentration from blood culture bottles for successful identification of five common Gram-positive and Gram-negative bacteria using MALDI-TOF MS 1.7-2.3 hours earlier than the usual time to detection in blood culture systems.
  
  
  CONCLUSIONS
  This study provides an approach to earlier identification of BSI pathogens prior to the detection of a positive signal in the blood culture system using MALDI-TOF MS, compared to current methods. It can speed the time for identification of BSI pathogens and may have benefits of earlier therapy choice and on patient outcome.
authors.affiliation: Division of Nephrology, Department of Internal Medicine, National Cheng Kung University Hospital, Tainan, Taiwan; Institute of Clinical Pharmacy and Pharmaceutical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Ming-Cheng
authors.initials: MC
authors.lastname: Wang
authors.affiliation: Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Wei-Hung
authors.initials: WH
authors.lastname: Lin
authors.affiliation: Department of Pathology, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Jing-Jou
authors.initials: JJ
authors.lastname: Yan
authors.affiliation: Department of Biotechnology, Chia Nan University of Pharmacy and Science, Tainan, Taiwan.
authors.forename: Hsin-Yi
authors.initials: HY
authors.lastname: Fang
authors.affiliation: Division of Nephrology, Department of Internal Medicine, National Cheng Kung University Hospital, Tainan, Taiwan.
authors.forename: Te-Hui
authors.initials: TH
authors.lastname: Kuo
authors.affiliation: Division of Nephrology, Department of Internal Medicine, National Cheng Kung University Hospital, Tainan, Taiwan.
authors.forename: Chin-Chung
authors.initials: CC
authors.lastname: Tseng
authors.affiliation: Department of Medical Laboratory Science and Biotechnology, College of Medicine, National Cheng Kung University, Tainan, Taiwan; Infectious Disease and Signaling Research Center, National Cheng Kung University, Tainan, Taiwan. Electronic address: jjwu@mail.ncku.edu.tw.
authors.forename: Jiunn-Jong
authors.initials: JJ
authors.lastname: Wu
mesh_terms: D000328:Adult; D016470:Bacteremia / Q000175:diagnosis / Q000382:microbiology*; D015373:Bacterial Typing Techniques / Q000379:methods*; D001769:Blood / Q000382:microbiology*; D042241:Early Diagnosis; D006801:Humans; D008828:Microbiological Techniques / Q000379:methods*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D013997:Time Factors
keywords: Blood culture system; Blood stream infection; Mass spectrometry; Matrix-assisted laser desorption ionization–time of flight mass spectrometry; Time to detection