Identification of Campylobacter species and related organisms by matrix assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry

Abstract

The identification of Campylobacter species and related organisms at the species level has always been difficult using phenotypic methods because of their low metabolic activity, whereas molecular methods are more reliable but time-consuming. In this study, 1007 different strains were identified using three different methods: conventional methods, molecular biology (real-time PCR and sequencing) and matrix assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry. Molecular methods were considered the gold standard. The accuracy of MALDI-TOF mass spectrometry reached 100% compared with the gold standard for all of the Campylobacter species, except Campylobacter jejuni (99.4%). The accuracy of conventional methods compared with the gold standard ranged from 0% to 100% depending on the species. However, MALDI-TOF mass spectrometry was not able to identify a mixture of two different species present in the same sample in four instances. Finally, MALDI-TOF mass spectrometry is highly recommended to identify Campylobacter spp. as only 0.4% discrepancy was found, whereas conventional methods led to 4.5% discrepancy.

Practical Guidance for Clinical Microbiology Laboratories: Diagnosis of Bacterial Gastroenteritis

“…Some have shown that SS and HE agars yield only genus-level identifications (284). For Campylobacter, colonies isolated on Campylosel and Columbia blood agar are FDA cleared on the Vitek MS and perform well for species-level identification (285)(286)(287)(288). In contrast, spectra are not generated when isolates are taken directly from modified CCDA; colonies isolated on this medium require subculture on a less selective medium prior to MALDI-TOF analysis (286).…”

Evaluation of Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry for Rapid Identification of Beta-Hemolytic Streptococci

“…Although the first descriptions of this method were published more than 10 years ago (5, 8), a wider use in routine microbiology laboratories became possible only recently when successful species identification for different genera was demonstrated (1,4,6,7,9,(11)(12)(13)(14). The most prominent advantages of the technology are speed and low cost (running cost), provided that a quality-controlled database of reference spectra, including all relevant microorganisms, is available.…”

Evaluation of Intact Cell Matrix-Assisted Laser Desorption/Ionization Timeof- Flight Mass Spectrometry for Capillary Electrophoresis Detection of Controlled Bacterial Clumping

“…The different nature of crystallization process results in different extraction mechanism of bacterial components. The signals obtained for ICM measurement were mostly of ribosomal-protein origin [25][26][27][28]. Circa 50% of the peaks of all bacteria unambiguously represented basic ribosomal proteins [1].…”

“…In screening analysis of microbial cells the use of these two matrices is common [23][24][25][26][27][28][29][30][31][32]. However, the spectra recorded with different matrices had different distribution of peaks ( Figure 3B, 3C).…”

“…The rest are cold-shock proteins, DNA-binding proteins and outermembrane lipoproteins [14]. Therefore, DHB will be the most favorable matrix for the analysis of lipoproteins, whereas in the case of intact cell measurements of DNA-binding proteins the use of HCCA will result in a higher number of signals [14,20,[25][26][27][28][29]. The similarities of spectra are not correlated in genetic genetic origin of phylogenetic trees.…”