Population Structure of Clinical Vibrio parahaemolyticus from 17 Coastal Countries, Determined through Multilocus Sequence Analysis

Abstract

Vibrio parahaemolyticus is a leading cause of food-borne gastroenteritis worldwide. Although this bacterium has been the subject of much research, the population structure of clinical strains from worldwide collections remains largely undescribed, and the recorded outbreaks of V. parahaemolyticus gastroenteritis highlight the need for the subtyping of this species. We present a broad phylogenetic analysis of 490 clinical V. parahaemolyticus isolates from 17 coastal countries through multilocus sequence analysis (MLST). The 490 tested isolates fell into 161 sequence types (STs). The eBURST algorithm revealed that the 161 clinically relevant STs belonged to 8 clonal complexes, 11 doublets, and 94 singletons, showing a high level of genetic diversity. CC3 was found to be a global epidemic clone of V. parahaemolyticus, and ST-3 was the only ST with an international distribution. recA was observed to be evolving more rapidly, exhibiting the highest degree of nucleotide diversity (0.028) and the largest number of polymorphic nucleotide sites (177). We also found that the high variability of recA was an important cause of differences between the results of the eBURST and ME tree analyses, suggesting that recA has a much greater influence on the apparent evolutionary classification of V. parahaemolyticus based on the current MLST scheme. In conclusion, it is evident that a high degree of genetic diversity within the V. parahaemolyticus population and multiple sequence types are contributing to the burden of disease around the world. MLST, with a fully extractable database, is a powerful system for analysis of the clonal relationships of strains at a global scale. With the addition of more strains, the pubMLST database will provide more detailed and accurate information, which will be conducive to our future research on the population structure of V. parahaemolyticus.

Combination of Multilocus Sequence Typing and GS‐PCR Reveals an Association of Pandemic Vibrio parahaemolyticus Clone with Clinical and Seafood Isolates

“…In particular, recA presented the greatest number of polymorphic nucleotide sites (56) and a high degree of nucleotide diversity (0.0209), although it was slightly lower than dtdS (0.0224) (Table ). This result was similar to a previous study that identified highly divergent recA alleles and this locus had the greatest influence on the phylogenetic relationships (Han et al., ).…”

Genetic relationships among Enterococcus faecalis isolates from different sources as revealed by multilocus sequence typing

“…The remaining 2 loci, recA and rpoB had 99 and 102 sites, respectively, suggesting recombination was evident and representing a significant source of genetic diversity in E. faecalis. High diversity in recA alleles and evidence for frequent recombination at this locus has been observed in previous studies (Han et al, 2014). In general, the allelic diversity of all 5 genes was less than 25%, indicating that the MLST design was balanced and corresponded with accepted designation principles (Maiden, 2006).…”

Prevalence and genetic diversity of human diarrheagenic Escherichia coli isolates by multilocus sequence typing

“…Among the seven genes analyzed, fumC and gyrB presented the highest degree of nucleotide diversity (0.03886 and 0.03075) and the greatest number of polymorphic nucleotide sites (137 and 139), suggesting that fumC and gyrB have much greater influences on the apparent evolutionary classification of human DEC. Together with the study by Han et al on Vibrio parahaemolyticus (recA dominant), this research helps us to understand the evolutionary relationships of these pathogens (Han et al, 2014). Previous MLST studies have confirmed recombination as a significant source of genetic diversity in DEC populations (Wirth et al, 2006).…”

“…Although there were differences between the results obtained from the eBURST algorithm and the ME tree, these two analytical tools each possess advantages. An eBURST analysis rapidly identifies CCs and their ancestral STs, while ME trees are superior in terms of revealing greater numbers of evolutionary relationships among different STs (Han et al, 2014).…”