title: Evaluation of a simple protein extraction method for species identification of clinically relevant staphylococci by matrix-assisted laser desorption ionization-time of flight mass spectrometry.
abstract: In clinical microbiology, bacterial identification is labor-intensive and time-consuming. A solution for this problem is the use of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). In this study, we evaluated a modified protein extraction method of identification performed on target plates (on-plate extraction method) with MALDI-TOF (Bruker Microflex LT with Biotyper version 3.0) and compared it to 2 previously described methods: the direct colony method and a standard protein extraction method (standard extraction method). We evaluated the species of 273 clinical strains and 14 reference strains of staphylococci. All isolates were characterized using the superoxide dismutase A sequence as a reference. For the species identification, the on-plate, standard extraction, and direct colony methods identified 257 isolates (89.5%), 232 isolates (80.8%), and 173 isolates (60.2%), respectively, with statistically significant differences among the three methods (P < 0.05). In conclusion, the on-plate extraction method is at least as good as standard extraction in identification rate and has the advantage of a shorter processing time.
authors.affiliation: Department of Infection Control Science, Faculty of Medicine, Juntendo University, Tokyo, Japan.
authors.forename: Naoto
authors.initials: N
authors.lastname: Matsuda
authors.forename: Mari
authors.initials: M
authors.lastname: Matsuda
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Notake
authors.forename: Hirohide
authors.initials: H
authors.lastname: Yokokawa
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Kawamura
authors.forename: Keiichi
authors.initials: K
authors.lastname: Hiramatsu
authors.forename: Ken
authors.initials: K
authors.lastname: Kikuchi
mesh_terms: D001426:Bacterial Proteins / Q000032:analysis* / Q000302:isolation & purification*; D001431:Bacteriological Techniques / Q000379:methods; D006801:Humans; D013048:Specimen Handling / Q000379:methods*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D013203:Staphylococcal Infections / Q000175:diagnosis / Q000382:microbiology; D013210:Staphylococcus / Q000737:chemistry* / Q000145:classification* / Q000302:isolation & purification
chemical_list: D001426:Bacterial Proteins