Abstract
BackgroundVibrio parahaemolyticus is frequently isolated from environmental and seafood samples and associated with gastroenteritis outbreakes in American, European, Asian and African countries. To distinguish between different lineages of V. parahaemolyticus various genotyping techniques have been used, incl. multilocus sequence typing (MLST). Even though some studies have already applied MLST analysis to characterize V. parahaemolyticus strain sets, these studies have been restricted to specific geographical areas (e.g. U.S. coast, Thailand and Peru), have focused exclusively on pandemic or non-pandemic pathogenic isolates or have been based on a limited strain number.ResultsTo generate a global picture of V. parahaemolyticus genotype distribution, a collection of 130 environmental and seafood related V. parahaemolyticus isolates of different geographical origins (Sri Lanka, Ecuador, North Sea and Baltic Sea as well as German retail) was subjected to MLST analysis after modification of gyrB and recA PCRs. The V. parahaemolyticus population was composed of 82 unique Sequence Types (STs), of which 68 (82.9%) were new to the pubMLST database. After translating the in-frame nucleotide sequences into amino acid sequences, less diversity was detectable: a total of 31 different peptide Sequence Types (pSTs) with 19 (61.3%) new pSTs were generated from the analyzed isolates. Most STs did not show a global dissemination, but some were supra-regionally distributed and clusters of STs were dependent on geographical origin. On peptide level no general clustering of strains from specific geographical regions was observed, thereby the most common pSTs were found on all continents (Asia, South America and Europe) and rare pSTs were restricted to distinct countries or even geographical regions. One lineage of pSTs associated only with strains from North and Baltic Sea strains was identified.ConclusionsOur study reveals a high genetic diversity in the analyzed V. parahaemolyticus strain set as well as for geographical strain subsets, with a high proportion of newly discovered alleles and STs. Differences between the subsets were identified. Our data support the postulated population structure of V. parahaemolyticus which follows the ‘epidemic’ model of clonal expansion. Application of peptide based AA-MLST allowed the identification of reliable relationships between strains.
Highlights
Vibrio parahaemolyticus is frequently isolated from environmental and seafood samples and associated with gastroenteritis outbreakes in American, European, Asian and African countries
Diversity of strain collection To evaluate completeness of the sampled diversity of strains present in the different geographical regions rarefaction curves were performed on the three geographical subsets, the complete strain set as well as on the entire pubMLST dataset
All observations regarding the diversity of (p)Sequence Type (ST), alleles, polymorphic sites, dN/dS and D were in concordance to the obtained values calculated on basis of all pubMLST entries (Table 1)
Summary
Vibrio parahaemolyticus is frequently isolated from environmental and seafood samples and associated with gastroenteritis outbreakes in American, European, Asian and African countries. Vibrio (V.) parahaemolyticus is naturally present in coastal waters worldwide [1,2,3,4]. It is associated with self-limiting gastroenteritis due to the ingestion of contaminated raw or undercooked seafood [5,6]. To distinguish between different lineages of V. parahaemolyticus various techniques have been used so far (e.g. serotyping, PFGE, rep-PCR), most promising multilocus sequence typing (MLST). Due to the nucleotide sequence based typing the comparison of results obtained by others and exchange via public databases is possible and allows continuously increasing understanding of the molecular epidemiology and evolution of the typed bacteria [12,13,14]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
