Comparison of Matrix-Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry with VITEK2 Gram positive system for identification of beta hemolytic Streptococci

Authors : Yeşim Beşli
Pages : 1-7
Doi:10.5455/jicm.29.20171123
View : 21 | Download : 6
Publication Date : 2018-03-30
Article Type : Research
Abstract :Background: Matrix–assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) is known as a successful tool for bacterial identification and suitable for clinical diagnostics. The aim of our study was to evaluate diagnostic accuracy of MALDI-TOF MS system and VITEK2 Gram Positive Identification (GP ID) system for the identification of Beta Hemolytic Streptococci (BHS). Materials and Methods: A total 148 BHS which were isolated from various clinical specimens were included in the study. Isolates were identified by Bruker Biotyper 3.4 and VITEK2 GP ID coupled to the agglutination test. Identification results for Bruker Biotyper 3.4 and VITEK2 GP ID systems were classified in three different categories as follows: correct identification, low level of discrimination, no identification/misidentification. Identification results of BHS were evaluated according to these categories. Results: BHS isolates were defined as Streptococcus pyogenes (n: 69), Streptococcus agalactiae (n: 59), Streptococcus dysgalactiae serogroup C (n: 5), and Streptococcus dysgalactiae serogroup G (n: 15) according to latex agglutination assay. MALDI-TOF MS analysis of 148 BHS isolates yielded correct identification for 89.9% of S. pyogenes , 64.4% of S. agalactiae , and 95.0% S. dysagalactiae serogroup C and G; while VITEK2 GP ID gave correct identification for 62.3% of S. pyogenes , 67.8% of S. agalactiae , and 65.0% of S. dysagalactiae serogroup C and G. Conclusions: MALDI-TOF MS-based identification provides faster and more accurate identification of beta-hemolytic streptococcal species than VITEK2 GP ID system.
Keywords : MALDI-TOF, VITEK, Beta Hemolytic Streptococci, S. pyogenes, S. agalactiae, S. dysagalactiae

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