Identification and phylogenetic analysis of Enterococcus isolates using MALDI-TOF MS and VITEK 2

• Published in: AMB Express Vol. 13; no. 1; p. 21
• Main Authors: Kim, Se-Hyung, Chon, Jung-Whan, Jeong, Hyo-Won, Song, Kwang-Young, Kim, Dong-Hyeon, Bae, Dongryeoul, Kim, Hyunsook, Seo, Kun-Ho
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 22.02.2023; Springer Nature B.V; SpringerOpen
• Subjects: 16S rRNA; Bacteria; Biochemical characteristics; Biomedical and Life Sciences; Biotechnology; Enterococcus; Food; Food spoilage; Gene sequencing; Identification; Ions; Laboratory methods; Life Sciences; MALDI-TOF MS; Mass spectrometry; Mass spectroscopy; Microbial Genetics and Genomics; Microbiology; Original; Original Article; Phylogenetics; Phylogeny; rRNA 16S; Shelf life; Species; Spoilage; Starter cultures; Urinary tract; VITEK 2; VITEK 2; MALDI-TOF MS; 16S rRNA; Identification; Enterococcus
• ISSN: 2191-0855; 2191-0855
• DOI: 10.1186/s13568-023-01525-y

The bacterial genus Enterococcus encompasses 38 species. Two of the most common species are E. faecalis and E. faecium . Recently, however, there has been an increase in clinical reports concerning less prevalent Enterococcus species, such as E. durans, E. hirae, and E. gallinarum. Rapid and accurate laboratory methods are needed to facilitate the identification of all these bacterial species. In the present study, we compared the relative accuracy of matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS), VITEK 2, and 16S rRNA gene sequencing using 39 enterococci isolates from dairy samples, and compared the resultant phylogenetic trees. We found that MALDI-TOF MS correctly identified all isolates at the species level except for one, whereas the VITEK 2 system, which is an automated identification system using biochemical characteristics of species, misidentified ten isolates. However, phylogenetic trees constructed from both methods showed all isolates in similar positions. Our results clearly showed that MALDI-TOF MS is a reliable and rapid tool for identifying Enterococcus species with greater discriminatory power than the biochemical assay method of VITEK 2. Key Points Although certain Enterococcus genus are used as starter cultures in many food products, this bacterial group is considered a human and animal pathogen which can cause nosocomical infections and urinary tract infections, and contribute to food spoilage. Accurate and reliable identification of Enterococcus genus present in food is of great importance for predicting shelf life and for managing and reducing microbiological food hazar. Phylogenetic trees obtained from MALDI-TOF MS and VITEK2 analyses were compared to evaluate the discriminative resolution of these two systems.