title: MALDI-TOF identification of Gram-negative bacteria directly from blood culture bottles containing charcoal: Sepsityper® kits versus centrifugation-filtration method.
abstract: Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry has dramatically altered the way microbiology laboratories identify clinical isolates. Direct blood culture (BC) detection may be hampered, however, by the presence of charcoal in BC bottles currently in clinical use. This study evaluates an in-house process for extraction and MALDI-TOF identification of Gram-negative bacteria directly from BC bottles containing charcoal. Three hundred BC aliquots were extracted by a centrifugation-filtration method developed in our research laboratory with the first 96 samples processed in parallel using Sepsityper® kits. Controls were colonies from solid media with standard phenotypic and MALDI-TOF identification. The identification of Gram-negative bacteria was successful more often via the in-house method compared to Sepsityper® kits (94.7% versus 78.1%, P≤0.0001). Our in-house centrifugation-filtration method was further validated for isolation and identification of Gram-negative bacteria (95%; n=300) directly from BC bottles containing charcoal.
authors: Department of Medical Education, St John Hospital and Medical Center, Detroit, MI, USA.
authors: Kathleen
authors: K
authors: Riederer
authors: Department of Medical Education, St John Hospital and Medical Center, Detroit, MI, USA.
authors: Kristian
authors: K
authors: Cruz
authors: Department of Medical Education, St John Hospital and Medical Center, Detroit, MI, USA.
authors: Stephen
authors: S
authors: Shemes
authors: Department of Medical Education, St John Hospital and Medical Center, Detroit, MI, USA.
authors: Susan
authors: S
authors: Szpunar
authors: Division of Infectious Diseases, St John Hospital and Medical Center, Detroit, MI, USA. Electronic address: joel.fishbain@stjohn.org.
authors: Joel T
authors: JT
authors: Fishbain
mesh_terms: D016470:Bacteremia / Q000175:diagnosis* / Q000382:microbiology*; D001769:Blood / Q000382:microbiology*; D002498:Centrifugation / Q000379:methods; D002606:Charcoal / Q000302:isolation & purification; D005374:Filtration / Q000379:methods; D006090:Gram-Negative Bacteria / Q000737:chemistry / Q000145:classification* / Q000302:isolation & purification*; D006801:Humans; D012680:Sensitivity and Specificity; D013048:Specimen Handling / Q000379:methods*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*
chemical_list: D002606:Charcoal
keywords: Blood culture; Charcoal bottles; Direct identification; Extraction method; Gram-negative bacteria; MALDI-TOF MS