title: Comparison of species identification of endocarditis associated viridans streptococci using rnpB genotyping and 2 MALDI-TOF systems.
abstract: Streptococcus spp. are important causes of infective endocarditis but challenging in species identification. This study compared identification based on sequence determination of the rnpB gene with 2 systems of matrix-assisted laser desorption ionization-time of flight mass spectrometry, MALDI Biotyper (Bruker) and VITEK MS IVD (bioMérieux). Blood culture isolates of viridans streptococci from 63 patients with infective endocarditis were tested. The 3 methods showed full agreement for all 36 isolates identified in the Anginosus, Bovis, and Mutans groups or identified as Streptococcus cristatus, Streptococcus gordonii, or Streptococcus sanguinis. None of the methods could reliably identify the 23 isolates to the species level when designated as Streptococcus mitis, Streptococcus oralis, or Streptococcus tigurinus. In 7 isolates classified to the Mitis group, the rnpB sequences deviated strikingly from all reference sequences, and additional analysis of sodA and groEL genes indicated the occurrence of yet unidentified Streptococcus spp.
authors.affiliation: Section of Clinical Bacteriology, Department of Medical Sciences, Uppsala University, SE-751 85 Uppsala, Sweden.
authors.forename: Jenny
authors.initials: J
authors.lastname: Isaksson
authors.affiliation: Division for Infection Medicine, Department of Clinical Sciences, Lund University, BMC B14, SE-22184 Lund, Sweden.
authors.forename: Magnus
authors.initials: M
authors.lastname: Rasmussen
authors.affiliation: Clinical Microbiology, Labmedicin, Region Skåne, SE-221 85 Lund, Sweden; Department of Laboratory Medicine Lund, Section of Medical Microbiology, Lund University, SE-22362 Lund, Sweden.
authors.forename: Bo
authors.initials: B
authors.lastname: Nilson
authors.affiliation: Department of Infectious Diseases, Sahlgrenska Academy, University of Gothenburg, SE-413 46 Gothenburg, Sweden.
authors.forename: Liselott Svensson
authors.initials: LS
authors.lastname: Stadler
authors.affiliation: Section of Infectious Diseases, Department of Medical Sciences, Uppsala University, SE-751 85 Uppsala, Sweden.
authors.forename: Siri
authors.initials: S
authors.lastname: Kurland
authors.affiliation: Department of Infectious Diseases, Institute of Biomedicine, University of Gothenburg, SE-416 85 Gothenburg, Sweden.
authors.forename: Lars
authors.initials: L
authors.lastname: Olaison
authors.affiliation: Section of Infectious Diseases, Department of Medical Sciences, University of Gothenburg, SE-413 46 Gothenburg, Sweden.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Ek
authors.affiliation: Section of Clinical Bacteriology, Department of Medical Sciences, Uppsala University, SE-751 85 Uppsala, Sweden. Electronic address: bjorn.herrmann@medsci.uu.se.
authors.forename: Björn
authors.initials: B
authors.lastname: Herrmann
mesh_terms: D004697:Endocarditis, Bacterial / Q000175:diagnosis* / Q000382:microbiology; D060005:Genotyping Techniques / Q000379:methods*; D006801:Humans; D012680:Sensitivity and Specificity; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D013290:Streptococcal Infections / Q000175:diagnosis* / Q000382:microbiology; D034363:Viridans Streptococci / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification*
keywords: Infective endocarditis; MALDI-TOF; Streptococcus spp; rnpB