title: Validation of a modified algorithm for the identification of yeast isolates using matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS).
abstract: Optimising antifungal treatment requires the fast and species-specific identification of yeast isolates. We evaluated a modified protocol for the rapid identification of clinical yeast isolates using matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) technology. First, we evaluated a simplified extraction procedure using 54 clinical yeast isolates. Second, we validated a new protocol with this simplified extraction procedure and lower identification threshold by analysing 167 isolates with either MALDI-TOF or conventional identification techniques. MALDI-TOF analysis with both the standard and short extraction procedure yielded identical identification results, although the log-scores were lower with the latter. With the modified protocol, 163/167 (97.6%) isolates showed a correct identification as compared to conventional identification techniques. A total of 135 out of the 163 (82.8%) correct identifications showed log-scores above 1.7, which we considered as the minimum log-score for secure species identification. The rapid identification of clinical yeast isolates is crucial in patient management. The MALDI-TOF technique using a short extraction procedure can be an alternative for the labourious standard procedure, although the log-scores will be lower. The identification of clinical yeast isolates with the modified protocol is a practical and accurate alternative for conventional identification techniques. If the isolate shows a log-score below 1.7, the standard extraction procedure should be used.
authors.affiliation: Department of Microbiology, ZNA Middelheim, Lindendreef 1, 2020, Antwerp, Belgium. brunovanherendael@gmail.com
authors.forename: B H
authors.initials: BH
authors.lastname: Van Herendael
authors.forename: P
authors.initials: P
authors.lastname: Bruynseels
authors.forename: M
authors.initials: M
authors.lastname: Bensaid
authors.forename: T
authors.initials: T
authors.lastname: Boekhout
authors.forename: T
authors.initials: T
authors.lastname: De Baere
authors.forename: I
authors.initials: I
authors.lastname: Surmont
authors.forename: A H
authors.initials: AH
authors.lastname: Mertens
mesh_terms: D000465:Algorithms; D019411:Clinical Laboratory Techniques / Q000379:methods*; D006801:Humans; D009172:Mycology / Q000379:methods*; D009181:Mycoses / Q000175:diagnosis* / Q000382:microbiology*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D015003:Yeasts / Q000737:chemistry* / Q000302:isolation & purification*