title: High-resolution subtyping of Staphylococcus aureus strains by means of Fourier-transform infrared spectroscopy.
abstract: Staphylococcus aureus causes a variety of serious illnesses in humans and animals. Subtyping of S. aureus isolates plays a crucial role in epidemiological investigations. Metabolic fingerprinting by Fourier-transform infrared (FTIR) spectroscopy is commonly used to identify microbes at species as well as subspecies level. In this study, we aimed to assess the suitability of FTIR spectroscopy as a tool for S. aureus subtyping. To this end, we compared the subtyping performance of FTIR spectroscopy to other subtyping methods such as pulsed field gel electrophoresis (PFGE) and spa typing in a blinded experimental setup and investigated the ability of FTIR spectroscopy for identifying S. aureus clonal complexes (CC). A total of 70 S. aureus strains from human, animal, and food sources were selected, for which clonal complexes and a unique virulence and resistance gene pattern had been determined by DNA microarray analysis. FTIR spectral analysis resulted in high discriminatory power similar as obtained by spa typing and PFGE. High directional concordance was found between FTIR spectroscopy based subtypes and capsular polysaccharide expression detected by FTIR spectroscopy and the cap specific locus, reflecting strain specific expression of capsular polysaccharides and/or other surface glycopolymers, such as wall teichoic acid, peptidoglycane, and lipoteichoic acid. Supervised chemometrics showed only limited possibilities for differentiation of S. aureus CC by FTIR spectroscopy with the exception of CC45 and CC705. In conclusion, FTIR spectroscopy represents a valuable tool for S. aureus subtyping, which complements current molecular and proteomic strain typing.
authors.affiliation: Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zurich, Winterthurerstrasse 272, CH-8057 Zurich, Switzerland.
authors.forename: Sophia
authors.initials: S
authors.lastname: Johler
authors.affiliation: Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zurich, Winterthurerstrasse 272, CH-8057 Zurich, Switzerland.
authors.forename: Roger
authors.initials: R
authors.lastname: Stephan
authors.affiliation: Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zurich, Winterthurerstrasse 272, CH-8057 Zurich, Switzerland.
authors.forename: Denise
authors.initials: D
authors.lastname: Althaus
authors.affiliation: Functional Microbiology, Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine Vienna, Veterinärplatz 1, AT-1210 Vienna, Austria.
authors.forename: Monika
authors.initials: M
authors.lastname: Ehling-Schulz
authors.affiliation: Functional Microbiology, Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine Vienna, Veterinärplatz 1, AT-1210 Vienna, Austria. Electronic address: tom.grunert@vetmeduni.ac.at.
authors.forename: Tom
authors.initials: T
authors.lastname: Grunert
mesh_terms: D000818:Animals; D016667:Bacterial Capsules / Q000145:classification; D015373:Bacterial Typing Techniques / Q000379:methods*; D016521:Electrophoresis, Gel, Pulsed-Field / Q000379:methods*; D006801:Humans; D008070:Lipopolysaccharides / Q000032:analysis; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods*; D010457:Peptidoglycan / Q000032:analysis; D011135:Polysaccharides, Bacterial / Q000145:classification; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D013211:Staphylococcus aureus / Q000145:classification* / Q000378:metabolism; D013682:Teichoic Acids / Q000032:analysis
chemical_list: D008070:Lipopolysaccharides; D010457:Peptidoglycan; D011135:Polysaccharides, Bacterial; D013682:Teichoic Acids; C009900:lipoteichoic acid
keywords: Capsular polysaccharide; DNA microarray; FTIR spectroscopy; Staphylococcus aureus; Subspecies typing; Surface glycopolymer