title: Rapid MALDI-TOF mass spectrometry strain typing during a large outbreak of Shiga-Toxigenic Escherichia coli.
abstract: BACKGROUND
  In 2011 northern Germany experienced a large outbreak of Shiga-Toxigenic Escherichia coli O104:H4. The large amount of samples sent to microbiology laboratories for epidemiological assessment highlighted the importance of fast and inexpensive typing procedures. We have therefore evaluated the applicability of a MALDI-TOF mass spectrometry based strategy for outbreak strain identification.
  
  
  METHODS
  Specific peaks in the outbreak strain's spectrum were identified by comparative analysis of archived pre-outbreak spectra that had been acquired for routine species-level identification. Proteins underlying these discriminatory peaks were identified by liquid chromatography tandem mass spectrometry and validated against publicly available databases. The resulting typing scheme was evaluated against PCR genotyping with 294 E. coli isolates from clinical samples collected during the outbreak.
  
  
  RESULTS
  Comparative spectrum analysis revealed two characteristic peaks at m/z 6711 and m/z 10883. The underlying proteins were found to be of low prevalence among genome sequenced E. coli strains. Marker peak detection correctly classified 292 of 293 study isolates, including all 104 outbreak isolates.
  
  
  CONCLUSIONS
  MALDI-TOF mass spectrometry allowed for reliable outbreak strain identification during a large outbreak of Shiga-Toxigenic E. coli. The applied typing strategy could probably be adapted to other typing tasks and might facilitate epidemiological surveys as part of the routine pathogen identification workflow.
authors.affiliation: Department of Medical Microbiology, Virology and Hygiene, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Christner
authors.affiliation: Institute of Organic Chemistry, Mass Spectrometry Facility, University of Hamburg, Hamburg, Germany.
authors.forename: Maria
authors.initials: M
authors.lastname: Trusch
authors.affiliation: Department of Medical Microbiology, Virology and Hygiene, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Holger
authors.initials: H
authors.lastname: Rohde
authors.affiliation: Department of Clinical Chemistry, Mass Spectrometric Proteomics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Marcel
authors.initials: M
authors.lastname: Kwiatkowski
authors.affiliation: Department of Clinical Chemistry, Mass Spectrometric Proteomics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Hartmut
authors.initials: H
authors.lastname: Schlüter
authors.affiliation: Department of Medical Microbiology, Virology and Hygiene, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Manuel
authors.initials: M
authors.lastname: Wolters
authors.affiliation: Department of Medical Microbiology, Virology and Hygiene, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Aepfelbacher
authors.affiliation: Department of Medical Microbiology, Virology and Hygiene, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Moritz
authors.initials: M
authors.lastname: Hentschke
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism; D015373:Bacterial Typing Techniques; D015415:Biomarkers / Q000378:metabolism; D004196:Disease Outbreaks; D004927:Escherichia coli Infections / Q000175:diagnosis* / Q000453:epidemiology / Q000382:microbiology; D005858:Germany / Q000453:epidemiology; D006801:Humans; D015203:Reproducibility of Results; D054323:Shiga-Toxigenic Escherichia coli / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D053719:Tandem Mass Spectrometry
chemical_list: D001426:Bacterial Proteins; D015415:Biomarkers