AUTHOR=Lee Meng-Rui , Tsai Chia-Jung , Teng Shih-Hua , Hsueh Po-Ren 

TITLE=Identification of Weissella species by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

JOURNAL=Frontiers in Microbiology

VOLUME=6

YEAR=2015

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2015.01246

DOI=10.3389/fmicb.2015.01246

ISSN=1664-302X

ABSTRACT=<p>Although some <italic>Weissella</italic> species play beneficial roles in food fermentation and in probiotic products, others such as <italic>Weissella confusa</italic> are emerging Gram-positive pathogens in immunocompromised hosts. <italic>Weissella</italic> species are difficult to identify by conventional biochemical methods and commercial automated systems and are easily misidentified as <italic>Lactobacillus</italic> and <italic>Leuconostoc</italic> species. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is increasingly being used for bacterial identification. Little, however, is known about the effectiveness of MALDI-TOF MS in identifying clinical isolates of <italic>Weissella</italic> to the species level. In this study, we evaluated whether the MALDI-TOF MS Bruker Biotyper system could accurately identify a total of 20 <italic>W. confusa</italic> and 2 <italic>W. cibaria</italic> blood isolates that had been confirmed by 16s rRNA sequencing analysis. The MALDI-TOF Biotyper system yielded no reliable identification results based on the current reference spectra for the two species (all score values &lt;1.7). New <italic>W. confusa</italic> spectra were created by randomly selecting 3 <italic>W. confusa</italic> isolates and external validation was performed by testing the remaining 17 <italic>W. confusa</italic> isolates using the new spectra. The new main spectra projection (MSP) yielded reliable score values of &gt;2 for all isolates with the exception of one (score value, 1.963). Our results showed that the MSPs in the current database are not sufficient for correctly identifying <italic>W. confusa</italic> or <italic>W. cibaria</italic>. Further studies including more <italic>Weissella</italic> isolates are warranted to further validate the performance of MALDI-TOF in identifying <italic>Weissella</italic> species.</p>