title: Rapid and reliable identification of Gram-negative bacteria and Gram-positive cocci by deposition of bacteria harvested from blood cultures onto the MALDI-TOF plate.
abstract: BACKGROUND
  Rapid identification of the causative agent(s) of bloodstream infections using the matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) methodology can lead to increased empirical antimicrobial therapy appropriateness. Herein, we aimed at establishing an easier and simpler method, further referred to as the direct method, using bacteria harvested by serum separator tubes from positive blood cultures and placed onto the polished steel target plate for rapid identification by MALDI-TOF. The results by the direct method were compared with those obtained by MALDI-TOF on bacteria isolated on solid media.
  
  
  RESULTS
  Identification of Gram-negative bacilli was 100 % concordant using the direct method or MALDI-TOF on isolated bacteria (96 % with score > 2.0). These two methods were 90 % concordant on Gram-positive cocci (32 % with score > 2.0). Identification by the SepsiTyper method of Gram-positive cocci gave concordant results with MALDI-TOF on isolated bacteria in 87 % of cases (37 % with score > 2.0).
  
  
  CONCLUSIONS
  The direct method herein developed allows rapid identification (within 30 min) of Gram-negative bacteria and Gram-positive cocci from positive blood cultures and can be used to rapidly report reliable and accurate results, without requiring skilled personnel or the use of expensive kits.
authors.affiliation: Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Università di Pisa, Via San Zeno 35-39, 56127, Pisa, Italy. s.barnini@ao-pisa.toscana.it.
authors.forename: Simona
authors.initials: S
authors.lastname: Barnini
authors.affiliation: Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Università di Pisa, Via San Zeno 35-39, 56127, Pisa, Italy. emilia.ghelardi@med.unipi.it.
authors.forename: Emilia
authors.initials: E
authors.lastname: Ghelardi
authors.affiliation: Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Università di Pisa, Via San Zeno 35-39, 56127, Pisa, Italy. veronicabrucculeri@yahoo.it.
authors.forename: Veronica
authors.initials: V
authors.lastname: Brucculeri
authors.affiliation: Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Università di Pisa, Via San Zeno 35-39, 56127, Pisa, Italy. paola.morici@for.unipi.it.
authors.forename: Paola
authors.initials: P
authors.lastname: Morici
authors.affiliation: Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Università di Pisa, Via San Zeno 35-39, 56127, Pisa, Italy. antonella.lupetti@med.unipi.it.
authors.forename: Antonella
authors.initials: A
authors.lastname: Lupetti
mesh_terms: D015373:Bacterial Typing Techniques / Q000191:economics / Q000295:instrumentation / Q000379:methods; D001769:Blood / Q000382:microbiology*; D006090:Gram-Negative Bacteria / Q000145:classification* / Q000302:isolation & purification; D006095:Gram-Positive Cocci / Q000145:classification* / Q000302:isolation & purification; D006801:Humans; D012680:Sensitivity and Specificity; D013045:Species Specificity; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000191:economics / Q000295:instrumentation* / Q000379:methods