title: Improved Differentiation of Streptococcus pneumoniae and Other S. mitis Group Streptococci by MALDI Biotyper Using an Improved MALDI Biotyper Database Content and a Novel Result Interpretation Algorithm.
abstract: Reliable distinction ofStreptococcus pneumoniaeand viridans group streptococci is important because of the different pathogenic properties of these organisms. Differentiation betweenS. pneumoniaeand closely relatedSreptococcusmitisspecies group streptococci has always been challenging, even when using such modern methods as 16S rRNA gene sequencing or matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry. In this study, a novel algorithm combined with an enhanced database was evaluated for differentiation betweenS. pneumoniaeandS. mitisspecies group streptococci. One hundred one clinicalS. mitisspecies group streptococcal strains and 188 clinicalS. pneumoniaestrains were identified by both the standard MALDI Biotyper database alone and that combined with a novel algorithm. The database update from 4,613 strains to 5,627 strains drastically improved the differentiation ofS. pneumoniaeandS. mitisspecies group streptococci: when the new database version containing 5,627 strains was used, only one of the 101S. mitisspecies group isolates was misidentified asS. pneumoniae, whereas 66 of them were misidentified asS. pneumoniaewhen the earlier 4,613-strain MALDI Biotyper database version was used. The updated MALDI Biotyper database combined with the novel algorithm showed even better performance, producing no misidentifications of theS. mitisspecies group strains asS. pneumoniaeAllS. pneumoniaestrains were correctly identified asS. pneumoniaewith both the standard MALDI Biotyper database and the standard MALDI Biotyper database combined with the novel algorithm. This new algorithm thus enables reliable differentiation between pneumococci and otherS. mitisspecies group streptococci with the MALDI Biotyper.
authors.affiliation: Clinical Microbiology Laboratory, Turku University Hospital, Turku, Finland inka.harju@tyks.fi.
authors.forename: Inka
authors.identifier: 0000-0002-2767-9127
authors.initials: I
authors.lastname: Harju
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: Bruker Daltonik GmbH, Bremen, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Maier
authors.affiliation: Clinical Microbiology Laboratory, Turku University Hospital, Turku, Finland.
authors.forename: Kaisu
authors.initials: K
authors.lastname: Rantakokko-Jalava
authors.affiliation: Bacterial Infections Unit, National Institute for Health and Welfare, Helsinki, Finland.
authors.forename: Marjo
authors.initials: M
authors.lastname: Haanperä
mesh_terms: D000465:Algorithms; D062126:Databases, Chemical; D006801:Humans; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D013290:Streptococcal Infections / Q000382:microbiology; D034361:Streptococcus mitis / Q000737:chemistry / Q000145:classification* / Q000302:isolation & purification; D013296:Streptococcus pneumoniae / Q000737:chemistry / Q000145:classification* / Q000302:isolation & purification
keywords: MALDI-TOF; Streptococcus pneumoniae; algorithm; mitis group streptococci; phenotypic identification; pneumococcus