Evaluation of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry system Clin-TOF-II MS in identification of gram-negative bacteria

Abstract

Objective To evaluate the performance of domestic matrix-assisted laser desorption/ionization time-of-flight mass spectrometry system Clin-TOF-Ⅱ MS with BioExplorer V2.3 database (Clin-TOF MS system) on gram-negative bacteria identification. Methods This was a methodological comparison study. A total of 1 025 gram-negative strains of 32 genus, 56 species or species complex were included in this study from 1999 to 2000 and 2014 to 2016 in Peking Union Medical College Hospital.The Bruker Biotyper MS system (Bruker MS system), Bruker Autoflex Speed with Biotyper v3.1 database were used as control. Identification by both MALDI-TOF MS systems were parallel conducted by direct smear method. The 16S rDNA sequencing based was performed when either MALDI-TOF MS system gave unbelievable result or results from two systems were not consistent. Results Amongst the isolates studied, 98.05% (1 005/1 025) was correctly identified to species or species complex level by Clin-TOF MS system. Comparatively, 99.22% (1 017/1 025) was correctly identified by Bruker MS system. There were 17 isolates just identified to genus level and 2 isolates were no identification by Clin-TOF MS system, meanwhile 1 Pseudomonas monteilii misidentified as P. putida. There were only two 2 isolates identified to genus level and 3 isolates were no identification by Bruker MS system. But it misidentified all 3 Aeromonas hydrophila (2 isolates as A. caviae and 1 isolate as A. media). It′s noted that both MS systems identified 1 Chryseobacterium gleum and 1 C. bernardetii to genus level. Conclusion The capability of domestic Clin-TOF MS system was good on gram-negative bacteria.(Chin J Lab Med, 2017, 40: 41-45) Key words: Gram-negative bacteria; Spectrometry, mass, matrix-assisted laser desorption-ionization