Differentiation of Gastric Helicobacter Species Using MALDI-TOF Mass Spectrometry

Abstract

Gastric helicobacters (Helicobacter (H.) pylori and non-H. pylori Helicobacter species (NHPHs)) colonize the stomach of humans and/or animals. Helicobacter species identification is essential since many of them are recognized as human and/or animal pathogens. Currently, Helicobacter species can only be differentiated using molecular methods. Differentiation between NHPHs using MALDI-TOF MS has not been described before, probably because these species are poorly represented in current MALDI-TOF MS databases. Therefore, we identified 93 gastric Helicobacter isolates of 10 different Helicobacter species using MALDI-TOF MS in order to establish a more elaborate Helicobacter reference database. While the MALDI Biotyper database was not able to correctly identify any of the isolates, the in-house database correctly identified all individual mass spectra and resulted in 82% correct species identification based on the two highest log score matches (with log scores ≥2). In addition, a dendrogram was constructed using all newly created main spectrum profiles. Nine main clusters were formed, with some phylogenetically closely related Helicobacter species clustering closely together and well-defined subclusters being observed in specific species. Current results suggest that MALDI-TOF MS allows rapid differentiation between gastric Helicobacter species, provided that an extensive database is at hand and variation due to growth conditions and agar-medium-related peaks are taken into account.

Helicobacter canis: A Review of Microbiological and Clinical Features

“…Only two reports partially succeeded in identifying H. canis by this technique with a score of 1.93 and 1.88, respectively ( Abidi et al, 2013 ; Mihevc et al, 2021 ). However, no reliable identification at genus level (log score ≥1.7) or species level (log score ≥2.0) is possible for Helicobacter species using the latest MALDI database ( Berlamont et al, 2021 ). Indeed, there are currently only two H. canis among the 24 Helicobacter entries in the MALDI Biotyper reference database library (Bruker Daltonics).…”

Differentiating between Enterococcusfaecium and Enterococcuslactis by Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry

“…lactis strain were incorporated. Raw spectra quality was evaluated using FlexAnalysis software version 3.4 (Bruker Daltonics, Bremen, Germany), whereby spectra displaying high background noise were deleted [ 24 ] according to the manufacturer’s instructions. After baseline subtraction and smoothing, >20 high-quality spectra were selected and transferred to create the main spectrum profile which was used for in-house database supplementation.…”

Evolution of Diagnostic Methods for Helicobacter pylori Infections: From Traditional Tests to High Technology, Advanced Sensitivity and Discrimination Tools

“…MALDI-TOF MS (matrix-assisted laser desorption/ionization–time-of-flight–mass spectrometry) is a new, precise, and low-cost approach that uses many forms of complicated fingerprints of specific biomarker molecules [ 75 , 76 ]. The main advantages of this technique are the fast procedure and lower expense compared to other conventional tests, a high degree of accuracy and sensitivity, the possibility to identify new species of H. pylori , the possibility of differentiating Helicobacter species [ 76 , 77 ], and to diagnose the antimicrobial resistance. In addition, a small amount of microbial biomass is required for the analysis (10 4 to 10 6 CFU).…”

“…Recently, 93 stomach Helicobacter isolates from ten different Helicobacter species were identified using MALDI-TOF MS to provide a more comprehensive Helicobacter reference library [ 76 ]. Construction of dendrograms based on a similarity matrix embedded in the unique program, MBT Compass Explorer 4.1, was used to assess species differentiation and diversity of spectra within a species.…”