title: Comprehensive MALDI-TOF biotyping of the non-redundant Harvard Pseudomonas aeruginosa PA14 transposon insertion mutant library.
abstract: BACKGROUND
  Pseudomonas aeruginosa is a gram-negative bacterium that is ubiquitously present in the aerobic biosphere. As an antibiotic-resistant facultative pathogen, it is a major cause of hospital-acquired infections. Its rapid and accurate identification is crucial in clinical and therapeutic environments.
  
  
  METHODS
  In a large-scale MALDI-TOF mass spectrometry-based screen of the Harvard transposon insertion mutant library of P. aeruginosa strain PA14, intact-cell proteome profile spectra of 5547 PA14 transposon mutants exhibiting a plethora of different phenotypes were acquired and analyzed.
  
  
  RESULTS
  Of all P. aeruginosa PA14 mutant profiles 99.7% were correctly identified as P. aeruginosa with the Biotyper software on the species level. On the strain level, 99.99% of the profiles were mapped to five different individual P. aeruginosa Biotyper database entries. A principal component analysis-based approach was used to determine the most important discriminatory mass features between these Biotyper groups. Although technical replicas were consistently categorized to specific Biotyper groups in 94.2% of the mutant profiles, biological replicas were not, indicating that the distinct proteotypes are affected by growth conditions.
  
  
  CONCLUSIONS
  The PA14 mutant profile collection presented here constitutes the largest coherent P. aeruginosa MALDI-TOF spectral dataset publicly available today. Transposon insertions in thousands of different P. aeruginosa genes did not affect species identification from MALDI-TOF mass spectra, clearly demonstrating the robustness of the approach. However, the assignment of the individual spectra to sub-groups proved to be non-consistent in biological replicas, indicating that the differentiation between biotyper groups in this nosocomial pathogen is unassured.
authors: Institute of Cell and Molecular Pathology, Hannover Medical School (MHH), Hannover, Germany.
authors: Tonio
authors: T
authors: Oumeraci
authors: Department of Molecular Bacteriology, Helmholtz Center for Infection Research, Braunschweig, Germany; Institute of Molecular Bacteriology, Twincore, Center for Experimental and Clinical Infection Research, A joint venture of the Helmholtz Center for Infection Research Braunschweig and the MHH, Hannover, Germany.
authors: Vanessa
authors: V
authors: Jensen
authors: Institute of Molecular and Cell Physiology, MHH, Hannover, Germany.
authors: Steven R
authors: SR
authors: Talbot
authors: Institute of Cell and Molecular Pathology, Hannover Medical School (MHH), Hannover, Germany.
authors: Winfried
authors: W
authors: Hofmann
authors: Bruker Daltonik GmbH, Bremen, Germany.
authors: Markus
authors: M
authors: Kostrzewa
authors: Institute of Cell and Molecular Pathology, Hannover Medical School (MHH), Hannover, Germany.
authors: Brigitte
authors: B
authors: Schlegelberger
authors: Institute of Cell and Molecular Pathology, Hannover Medical School (MHH), Hannover, Germany.
authors: Nils
authors: N
authors: von Neuhoff
authors: Department of Molecular Bacteriology, Helmholtz Center for Infection Research, Braunschweig, Germany; Institute of Molecular Bacteriology, Twincore, Center for Experimental and Clinical Infection Research, A joint venture of the Helmholtz Center for Infection Research Braunschweig and the MHH, Hannover, Germany.
authors: Susanne
authors: S
authors: Häussler
mesh_terms: D015723:Gene Library; D016254:Mutagenesis, Insertional / Q000235:genetics*; D016533:Mycological Typing Techniques / Q000379:methods; D011550:Pseudomonas aeruginosa / Q000235:genetics*; D012984:Software; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods