Distribution of Virulence Markers among Vibrio vulnificus Isolates of Clinical and Environmental Origin and Regional Characteristics in Japan

Abstract

Background Vibrio vulnificus is an opportunistic human pathogen that is widely distributed in estuarine environments and is capable of causing necrotizing fasciitis and sepsis. In Japan, based on epidemiological research, the incidences of V. vulnificus were concentrated in Kyusyu, mainly in coastal areas of the Ariake Sea. To examine the virulence potential, various genotyping methods have recently been developed. This study aimed to investigate the distribution of virulence markers among V. vulnificus isolates of clinical and environmental origin in three coastal areas with different infection incidences and to determine whether these isolates have the siderophore encoding gene viuB.Methodology/Principal FindingsWe examined the distribution of genotypes of the 16S ribosomal ribonucleic acid (rRNA) gene, vvhA, vcg, and capsular polysaccharide (CPS), and the presence of viuB in 156 isolates collected from patients and environmental samples in Japan. The environmental samples were collected from three coastal areas: the Ariake Sea, Ise & Mikawa Bay, and Karatsu Bay. The results showed disparity in the ratios of genotypes depending on the sample origins. V. vulnificus isolates obtained from patients were classified into the clinical type for all genotypes. In the environmental isolates, the ratios of the clinical type for genotypes of the 16S rRNA gene, vvhA, and vcg were in the order of the Ariake Sea>Ise & Mikawa Bay>Karatsu Bay. Meanwhile, CPS analysis showed no significant difference. Most isolates possessed viuB.ConclusionsMany V. vulnificus belonging to the clinical type existed in the Ariake Sea. Three coastal areas with different infection incidences showed distinct ratios of genotypes. This may indicate that the distribution of clinical isolates correlates with the incidence of V. vulnificus infection.

Genotypic Diversity and Population Structure of Vibrio vulnificus Strains Isolated in Taiwan and Korea as Determined by Multilocus Sequence Typing

“…A marginal association ( p = 0.097) was observed for the 16S rRNA and pilF genotypes, with degrees of association < 50%. Our results are consistent with those of a recent study of VV strains isolated in Japan [ 38 ]. In this study, P genotypes for the 16S rRNA gene, CPS, and vcg dominated both in clinical strains and in environmental strains.…”

“…To evaluate and predict the virulence of different V . vulnificus strains, several genotyping methods have been developed [ 30 – 38 ]. Although genotyping studies are not a substitute for animal models for evaluating the virulence of V .…”

Virulence Profiles of Vibrio vulnificus in German Coastal Waters, a Comparison of North Sea and Baltic Sea Isolates

“…Several MLST analyses conducted on V. vulnificus demonstrated that the majority of strains of MLST cluster II are of clinical origin [ 8 , 9 , 10 , 11 , 16 , 37 ]. This cluster is also highly correlated with the clinical associated alleles of the vcg and 16S rRNA genes ( vcg -type C, 16S rRNA-type B) that are often used to predict strain virulence [ 12 , 13 , 39 ]. In addition, the majority of cluster II strains are positive for the nanA gene, region XII, and mannitol fermentation which are traits associated with clinical origin [ 10 , 11 , 16 , 36 ].…”

Detection of Vibrio parahaemolyticus, Vibrio vulnificus and Vibrio cholerae with respect to seasonal fluctuations in temperature and plankton abundance

“…Additionally, we used gene targets commonly found among clinical isolates, including the thermostable direct and related hemolysins ( trh and tdh respectively) (Bej et al ., ) of V. parahaemolyticus , the siderophore‐related viu B (Panicker et al ., ) of V. vulnificus , and the wbe O and rfb specific to V. cholerae O1 and O139 serotypes (Hoshino et al ., ; Rivera et al ., ), as well as ctx A (encoding the A subunit of cholera toxin) (Fields et al ., ), tox R (a global regulatory gene) and tcp A (encoding the toxin‐coregulated pilus) (Rivera et al ., ) of V. cholerae . Although previous studies have shown the siderophore‐encoding viu B of V. vulnificus to be preferentially distributed among clinical isolates (Panicker et al ., ; Han et al ., ), additional studies suggest this gene may be widely distributed among environmental strains (Bogard and Oliver, ; Yokochi et al ., ).…”