Identification of Yersinia enterocolitica isolates from humans, pigs and wild boars by MALDI TOF MS

Abstract

BackgroundYersinia enterocolitica is widespread within the humans, pigs and wild boars. The low isolation rate of Y. enterocolitica from food or environmental and clinical samples may be caused by limited sensitivity of culture methods. The main goal of present study was identification of presumptive Y. enterocolitica isolates using MALDI TOF MS. The identification of isolates may be difficult due to variability of bacterial strains in terms of biochemical characteristics. This work emphasizes the necessity of use of multiple methods for zoonotic Y. enterocolitica identification.ResultsIdentification of Y. enterocolitica isolates was based on MALDI TOF MS, and verified by VITEK® 2 Compact and PCR. There were no discrepancies in identification of all human’ and pig’ isolates using MALDI TOF MS and VITEK® 2 Compact. However three isolates from wild boars were not decisively confirmed as Y. enterocolitica. MALDI TOF MS has identified the wild boar’ isolates designated as 3dz, 4dz, 8dz as Y. enterocolitica with a high score of matching with the reference spectra of MALDI Biotyper. In turn, VITEK® 2 Compact identified 3dz and 8dz as Y. kristensenii, and isolate 4dz as Y. enterocolitica. The PCR for Y. enterocolitica 16S rDNA for these three isolates was negative, but the 16S rDNA sequence analysis identified these isolates as Y. kristensenii (3dz, 4dz) and Y. pekkanenii (8dz). The wild boar’ isolates 3dz, 4dz and 8dz could not be classified using biotyping. The main bioserotype present within pigs and human faeces was 4/O:3. It has been shown that Y. enterocolitica 1B/O:8 can be isolated from human faeces using ITC/CIN culturing.ConclusionThe results of our study indicate wild boars as a reservoir of new and atypical strains of Yersinia, for which protein and biochemical profiles are not included in the MALDI Biotyper or VITEK® 2 Compact databases. Pigs in the south-west Poland are the reservoir for pathogenic Y. enterocolitica strains. Four biochemical features included in VITEK® 2 Compact known to be common with Wauters scheme were shown to produce incompatible results, thus VITEK® 2 Compact cannot be applied in biotyping of Y. enterocolitica.

Genetic Diversity and Distribution of Virulence-Associated Genes in Y. enterocolitica and Y. enterocolitica-Like Isolates from Humans and Animals in Poland

“…The Y. enterocolitica occurrence in wild boars in Poland has so far been confirmed by Morka K. et al in western Poland in 2018 [ 27 ], Syczyło et al in 2016 [ 28 ] during 2011–2014 hunting seasons mainly in North-Eastern Poland, Syczyło et al in 2018 [ 29 ] in 12 out of 16 Polish districts across Poland during the hunting seasons of 2013–2014, Bancerz-Kisiel et al in 2015 [ 30 ] in North-East Poland during the 2013 hunting season and Bancerz-Kisiel et al in 2015 [ 31 ] in two voivodeships of northern Poland, one voivodeship of central Poland and from two voivodeships of southern Poland. Only one paper, a published dissertation, indicated the endemic or alluvial origin of Y. enterocolitica strains isolated from people in the years 1996–2008 [ 32 ].…”

“…The common assumption that only Y. enterocolitica , Y. pseudotuberculosis and Y. pestis are clinically relevant and the remaining species are environmental may have an impact on the identification of potential new hosts that can cause human disease. This also leads to overrepresentation of clinical Y. enterocolitica strains in databases and a limited number of representative Y. enterocolitica -like species in matrix-assisted laser desorption/ionization (MALD)I Biotyper or VITEK ® 2 Compact (bioMérieux) databases, which together require an application of several identification methods simultaneously, what was highlighted in a recently published paper [ 27 ].…”

Cloacal Gram-Negative Microbiota in Free-Living Grass Snake Natrix natrix from Poland

“…Pure single colonies of actively growing cultures were mixed to obtained a bacterial suspension in 300 μL of water, then fixed by the addition of 900 μL absolute ethanol, which was followed by extraction procedure as previously described [ 24 , 25 ]. Bacterial strains were identified by MALDI-TOF MS and all analyses were performed with an UltrafleXtreme mass spectrometer (Bruker Daltonics, Germany) using the Biotyper 3.1 software and database containing 4613 entries.…”

Pleural empyema due to Salmonella in a patient with bronchogenic carcinoma: the first case report from a cancer hospital in Egypt

“…Biochemical reactions, including Triple Sugar Iron (TSI) slant, which revealed alkali, TSI butt, which revealed acid, Lysine Iron Agar (LIA) (positive), Sulfur Indole Motility (SIM) (Sulfide positive, Indole negative, Motility positive), citrate (positive) and urease (negative) were done, which revealed the growth of Salmonella species according to the WHO laboratory protocol for biochemical identification of Salmonella and Shigella [8]. The results were confirmed using VITEK 2 COMPACT, an automated microbial identification system commonly used for microbial identification in clinical laboratories , which eliminates human subjectivity [9]. Using pure isolates of organisms to be tested, VITEK 2 Compact allows the identification of micro-organisms in 4 hours.…”

“…Using pure isolates of organisms to be tested, VITEK 2 Compact allows the identification of micro-organisms in 4 hours. The system uses fluorogenic and turbidimetric methods for organism identification and susceptibility testing, respectively [9].…”