title: Identification and susceptibility testing of microorganism by direct inoculation from positive blood culture bottles by combining MALDI-TOF and Vitek-2 Compact is rapid and effective.
abstract: OBJECTIVE
  The objective of this study was to evaluate the reliability and accuracy of the combined use of MALDI-TOF MS bacterial identification and the Vitek-2 Compact antimicrobial susceptibility testing (AST) directly from positive blood cultures.
  
  
  METHODS
  Direct identification by MALDI-TOF MS and AST were performed in parallel to the standard methods in all positively flagged blood cultures bottles during the study period.
  
  
  RESULTS
  Three hundred and twenty four monomicrobial positive blood cultures were included in the present study, with 257 Gram-negative and 67 Gram-positive isolates. MALDI-TOF MS identification directly from blood bottles reported the correct identification for Enterobacteriaceae in 97.7%, non-fermentative Gram-negative bacilli 75.0%, Staphylococcus aureus 75.8%, coagulase negative staphylococci 63.3% and enterococci 63.3%. A total 6156 isolate/antimicrobial agent combinations were tested. Enterobacteriaceae group and non-fermentative Gram-negative Bacilli showed an agreement of 96.67% and 92.30%, respectively, for the Gram-positive cocci the overall agreement found was 97.84%.
  
  
  CONCLUSIONS
  We conclude that direct identification by MALDI-TOF and inoculation of Vitek-2 Compact AST with positive blood culture bottles yielded very good results and decreased time between initial inoculation of blood culture media and determination of the antibiotic susceptibility for Gram-negative rods and Gram-positive cocci causing bacteremia.
authors.affiliation: Servicio de Microbiología y Parasitología, Hospital Universitario La Paz, Paseo de la Castellana 261, 28046 Madrid, Spain. mpromero.hulp@salud.madrid.org
authors.forename: María-Pilar
authors.initials: MP
authors.lastname: Romero-Gómez
authors.forename: Rosa
authors.initials: R
authors.lastname: Gómez-Gil
authors.forename: Jose Ramón
authors.initials: JR
authors.lastname: Paño-Pardo
authors.forename: Jesús
authors.initials: J
authors.lastname: Mingorance
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D016470:Bacteremia / Q000097:blood / Q000382:microbiology*; D015373:Bacterial Typing Techniques / Q000379:methods*; D006090:Gram-Negative Bacteria / Q000737:chemistry / Q000145:classification* / Q000187:drug effects* / Q000302:isolation & purification; D006094:Gram-Positive Bacteria / Q000737:chemistry / Q000145:classification* / Q000187:drug effects* / Q000302:isolation & purification; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*
chemical_list: D000900:Anti-Bacterial Agents