title: Evaluation of two matrix-assisted laser desorption ionization-time of flight mass spectrometry systems for identification of viridans group streptococci.
abstract: In this study, the performances of two matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) systems, MALDI Biotyper (Bruker Daltonics) and VITEK MS (bioMérieux), were evaluated in the identification of viridans group streptococci. Two collections of isolates were tested with both methods. From a panel of type collection strains (n = 54), MALDI Biotyper gave correct species-level identification for 51/54 (94 %) strains and 37/54 (69 %) strains for the VITEK MS in vitro diagnostic (IVD) method. Additionally, a collection of blood cultures isolates which had been characterized earlier with partial sequencing of 16S rRNA (n = 97) was analyzed. MALDI Biotyper classified 89 % and VITEK MS 93 % of these correctly to the group level. Comparison of species-level identification from the blood culture collection was possible for 36 strains. MALDI Biotyper identified 75 % and VITEK MS 97 % of these strains consistently. Among the clinical isolates, MALDI Biotyper misidentified 36 strains as Streptococcus pneumoniae. Nevertheless, our results suggest that the current MALDI-TOF methods are a good alternative for the identification of viridans streptococci and do perform as well as or better than commercial phenotypical methods.
authors.affiliation: Department of Clinical Microbiology, Päijät-Häme Social and Health Care Group, Center of Medical Services, Keskussairaalankatu 7, 15850, Lahti, Finland, pauliina.karpanoja@phsotey.fi.
authors.forename: P
authors.initials: P
authors.lastname: Kärpänoja
authors.forename: I
authors.initials: I
authors.lastname: Harju
authors.forename: K
authors.initials: K
authors.lastname: Rantakokko-Jalava
authors.forename: M
authors.initials: M
authors.lastname: Haanperä
authors.forename: H
authors.initials: H
authors.lastname: Sarkkinen
mesh_terms: D019411:Clinical Laboratory Techniques / Q000379:methods*; D006801:Humans; D008828:Microbiological Techniques / Q000379:methods*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D013290:Streptococcal Infections / Q000175:diagnosis* / Q000382:microbiology; D034363:Viridans Streptococci / Q000737:chemistry / Q000145:classification* / Q000302:isolation & purification*