title: Evaluation of a Semiquantitative Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry Method for Rapid Antimicrobial Susceptibility Testing of Positive Blood Cultures.
abstract: With the increasing prevalence of multidrug-resistant Gram-negative bacteria, rapid identification of the pathogen and its individual antibiotic resistance is crucial to ensure adequate antiinfective treatment at the earliest time point. Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry for the identification of bacteria directly from the blood culture bottle has been widely established; however, there is still an urgent need for new methods that permit rapid resistance testing. Recently, a semiquantitative MALDI-TOF mass spectrometry-based method for the prediction of antibiotic resistance was described. We evaluated this method for detecting nonsusceptibility against two β-lactam and two non-β-lactam antibiotics. A collection of 30 spiked blood cultures was tested for nonsusceptibility against gentamicin and ciprofloxacin. Furthermore, 99 patient-derived blood cultures were tested for nonsusceptibility against cefotaxime, piperacillin-tazobactam, and ciprofloxacin in parallel with MALDI-TOF mass spectrometry identification from the blood culture fluid. The assay correctly classified all isolates tested for nonsusceptibility against gentamicin and cefotaxime. One misclassification for ciprofloxacin nonsusceptibility and five misclassifications for piperacillin-tazobactam nonsusceptibility occurred. Identification of the bacterium and prediction of nonsusceptibility was possible within approximately 4 h.
authors.affiliation: Max von Pettenkofer-Institut für Hygiene und Medizinische Mikrobiologie, Munich, Germany jung@mvp.uni-muenchen.de.
authors.forename: Jette S
authors.initials: JS
authors.lastname: Jung
authors.affiliation: Max von Pettenkofer-Institut für Hygiene und Medizinische Mikrobiologie, Munich, Germany.
authors.forename: Christina
authors.initials: C
authors.lastname: Hamacher
authors.affiliation: Max von Pettenkofer-Institut für Hygiene und Medizinische Mikrobiologie, Munich, Germany.
authors.forename: Birgit
authors.initials: B
authors.lastname: Gross
authors.affiliation: Bruker Daltonik GmbH, Bremen, Germany.
authors.forename: Katrin
authors.initials: K
authors.lastname: Sparbier
authors.affiliation: Bruker Daltonik GmbH, Bremen, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Lange
authors.affiliation: Bruker Daltonik GmbH, Bremen, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Kostrzewa
authors.affiliation: Max von Pettenkofer-Institut für Hygiene und Medizinische Mikrobiologie, Munich, Germany.
authors.forename: Sören
authors.initials: S
authors.lastname: Schubert
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000071997:Blood Culture; D003951:Diagnostic Errors; D024881:Drug Resistance, Bacterial; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D013997:Time Factors
chemical_list: D000900:Anti-Bacterial Agents