title: Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF) directly from positive blood culture flasks allows rapid identification of bloodstream infections in immunosuppressed hosts.
abstract: BACKGROUND
  In immunosuppressed hosts, rapid identification of microorganisms of bloodstream infections is crucial to ensuring effective antimicrobial therapy. Conventional culture requires up to 72 h from sample collection to pathogen identification.
  
  
  METHODS
  We used the SepsiTyper Kit and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF; Microflex, Bruker) directly from positive blood culture (BacT/ALERT 3D, FN/FA vials; bioMérieux) in comparison to standard culture methodology (VITEK 2; bioMérieux) for species identification.
  
  
  RESULTS
  A total of 62 consecutive positive blood cultures from immunosuppressed patients (solid organ or hematopoietic transplant recipients, or with febrile neutropenia) were analyzed. Culture yielded gram-negative bacteria (GNB) in 27/62 (43.5%) and gram-positive (GPB) in 35/62 (56.5%) vials. For GNB, the predominant species identified by MALDI-TOF and confirmed by VITEK were Escherichia coli (16/16 correctly identified) and Enterobacter cloacae (4/4), with a sensitivity and specificity of 92.6% and 100%, respectively. For GPB, predominant species were Staphylococcus aureus (3/3), coagulase-negative staphylococci (12/24), and Enterococcus faecium (6/6) with a sensitivity of 100%, 60%, and 100%, respectively. The median time from blood collection to species identification was 27.4 h with MALDI-TOF identification and 46.6 h with conventional methodology.
  
  
  CONCLUSIONS
  Using MALDI-TOF directly from positive blood cultures allowed a shorter time to identification with high sensitivity and specificity in immunosuppressed patients.
authors.affiliation: Division of Clinical Microbiology, University Hospital Basel, Basel, Switzerland.|Vaccine Research Infection Biology Lab, Department Biomedicine, University of Basel, Basel, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Egli
authors.affiliation: Division of Infectious Diseases and Hospital Epidemiology, University Hospital Basel, Basel, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Osthoff
authors.affiliation: Division of Clinical Microbiology, University Hospital Basel, Basel, Switzerland.
authors.forename: D
authors.initials: D
authors.lastname: Goldenberger
authors.affiliation: Hematology, University Hospital Basel, Basel, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Halter
authors.affiliation: Division of Nephrology and Transplant Immunology, University Hospital Basel, Basel, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: Schaub
authors.affiliation: Division of Nephrology and Transplant Immunology, University Hospital Basel, Basel, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Steiger
authors.affiliation: Division of Infectious Diseases and Hospital Epidemiology, University Hospital Basel, Basel, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Weisser
authors.affiliation: Division of Clinical Microbiology, University Hospital Basel, Basel, Switzerland.
authors.forename: R
authors.initials: R
authors.lastname: Frei
mesh_terms: D016470:Bacteremia / Q000175:diagnosis*; D015331:Cohort Studies; D003141:Communicable Diseases / Q000175:diagnosis* / Q000382:microbiology; D006090:Gram-Negative Bacteria / Q000302:isolation & purification*; D006094:Gram-Positive Bacteria / Q000302:isolation & purification*; D006801:Humans; D016867:Immunocompromised Host; D012680:Sensitivity and Specificity; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D013997:Time Factors
keywords: MALDI-TOF; bacteria; blood culture; chemotherapy; immunosuppression; neutropenia; oncology; sepsis; transplantation