The Trend of Vibrio parahaemolyticus Infections in Southern Thailand from 2006 to 2010

Thongjun, Junthip; Mittraparp‐arthorn, Pimonsri; Yingkajorn, Mingkwan; Kongreung, Jetnapang; Nishibuchi, Mitsuaki; Vuddhakul, Varaporn

doi:10.2149/tmh.2013-06

Cited by 33 publications

(19 citation statements)

References 17 publications

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“…There are many reports of tdh-positive V. parahaemolyticus infection. However, reports of foodborne infections caused by tdh-negative and trh-positive V. parahaemolyticus are limited (Ikeda et al, 1997;Thongjun et al, 2013).…”

Section: -2007mentioning

confidence: 99%

Epidemiological Evidence of Lesser Role of Thermostable Direct Hemolysin (TDH)–Related Hemolysin (TRH) Than TDH onVibrio parahaemolyticusPathogenicity

Saito¹,

Iwade

Tokuoka

et al. 2015

Foodborne Pathogens and Disease

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Vibrio parahaemolyticus carrying the tdh gene, encoding the thermostable direct hemolysin (TDH), or the trh gene, encoding the TDH-related hemolysin (TRH), are both considered virulent strains. There are, however, disproportionally fewer reports of infections caused by seafood contaminated with trh-positive strains than by seafood contaminated with tdh-positive strains. Bivalves such as clams and oysters are the major seafood varieties associated with the infections. In this study, the prevalence of strains possessing the tdh and trh genes was investigated in Japan in 74 samples collected in 2007-2008 and in 177 samples collected in 2010 of domestic bivalves, bloody clams, hen clams, short-neck clams, and rock oysters. The tdh-positive and trh-negative, tdh-negative and trh-positive, and tdh-positive and trh-positive samples represented 5.4%, 12.2%, and 4.1% of all samples collected in 2007-2008, and 5.1%, 18.6%, and 5.6% of all samples collected in 2010, respectively. As determined by polymerase chain reaction, the prevalence of tdh negative and trh positive in all samples was two to four times higher than that of tdh positive and trh negative. In the samples collected in 2010, the tdh-negative and trh-positive V. parahaemolyticus (20 samples) was more often isolated than tdh-positive and trh-negative V. parahaemolyticus (7 samples). The most common serotype of tdh-positive isolates (22 of 24 strains) was pandemic O3:K6. The trh-positive isolates (61 strains) were various serotypes including OUT:KUT. In 330 V. parahaemolyticus outbreaks and sporadic infections in Japan, most outbreaks and sporadic infections were caused by tdh-positive and trh-negative strains (89.4%). The frequencies of infections caused by tdh-negative and trh-positive, and both tdh- and trh-positive strains were 1.2% and 3.0%, respectively. This finding suggests that the virulence of trh might be less than that of tdh, although trh-positive V. parahaemolyticus frequently contaminated bivalves.

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Section: -2007mentioning

confidence: 99%

Epidemiological Evidence of Lesser Role of Thermostable Direct Hemolysin (TDH)–Related Hemolysin (TRH) Than TDH onVibrio parahaemolyticusPathogenicity

Saito¹,

Iwade

Tokuoka

et al. 2015

Foodborne Pathogens and Disease

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“…2 ) also exhibited the trh2–3 gene and shared the same ST as VN-0029. In other parts of the world the detection of trh in clinical isolates is dominant with 22% ( trh only) and 59% ( trh/tdh ) in Canada [ 42 ], 8.3% ( trh only) and 24.3% ( trh/tdh ) in North America [ 43 ], and 8% ( trh only) and 34% ( trh/tdh ) in Thailand [ 44 ]. In the cited publications, there was no differentiation between trh1 and trh2 .…”

Section: Discussionmentioning

confidence: 99%

Characterization of trh2 Harbouring Vibrio parahaemolyticus Strains Isolated in Germany

et al. 2015

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Background Vibrio parahaemolyticus is a recognized human enteropathogen. Thermostable direct hemolysin (TDH) and TDH-related hemolysin (TRH) as well as the type III secretion system 2 (T3SS2) are considered as major virulence factors. As tdh positive strains are not detected in coastal waters of Germany, we focused on the characterization of trh positive strains, which were isolated from mussels, seawater and patients in Germany.ResultsTen trh harbouring V. parahaemolyticus strains from Germany were compared to twenty-one trh positive strains from other countries. The complete trh sequences revealed clustering into three different types: trh1 and trh2 genes and a pseudogene Ψtrh. All German isolates possessed alleles of the trh2 gene. MLST analysis indicated a close relationship to Norwegian isolates suggesting that these strains belong to the autochthonous microflora of Northern Europe seawaters. Strains carrying the pseudogene Ψtrh were negative for T3SS2β effector vopC. Transcription of trh and vopC genes was analyzed under different growth conditions. Trh2 gene expression was not altered by bile while trh1 genes were inducible. VopC could be induced by urea in trh2 bearing strains. Most trh1 carrying strains were hemolytic against sheep erythrocytes while all trh2 positive strains did not show any hemolytic activity. TRH variants were synthesized in a prokaryotic cell-free system and their hemolytic activity was analyzed. TRH1 was active against sheep erythrocytes while TRH2 variants were not active at all.ConclusionOur study reveals a high diversity among trh positive V. parahaemolyticus strains. The function of TRH2 hemolysins and the role of the pseudogene Ψtrh as pathogenicity factors are questionable. To assess the pathogenic potential of V. parahaemolyticus strains a differentiation of trh variants and the detection of T3SS2β components like vopC would improve the V. parahaemolyticus diagnostics and could lead to a refinement of the risk assessment in food analyses and clinical diagnostics.

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“…The current state of knowledge supports multiple points of view on the utility of hemolysins as a diagnostic trait, even with their strong correlation with clinical isolation (Nishibuchi et al, 1992 ; Honda and Iida, 1993 ; Xu et al, 1994 ; García et al, 2009 ; Hiyoshi et al, 2010 ; Thongjun et al, 2013 ; Banerjee et al, 2014 ). It is concerning that 14% of clinical isolates, 11% if counting those from gastric infections only, harbored neither hemolysin gene (Table 2 ), and therefore, these strains would evade detection as human pathogens in any monitoring program relying upon only these markers.…”

Section: Discussionmentioning

confidence: 56%

“…Few of the diagnostic markers most commonly used to define pathogens are actually implicated in disease, including two hemolysin genes ( tdh and trh ) and a horizontally acquired type-three secretion system (T3SS2) (Honda and Iida, 1993 ; Hiyoshi et al, 2010 ). Although hemolysins are sufficient for inducing some disease symptoms, they are not necessary for disease in either mice or humans, indicating they are not the only virulence determinant (Nishibuchi et al, 1992 ; Xu et al, 1994 ; García et al, 2009 ; Thongjun et al, 2013 ; Banerjee et al, 2014 ). Perhaps more concerning, the abundance of hemolysin-containing strains in the environment often does not correlate with increased incidence of disease, calling into question the ability of these markers to sufficiently predict risk evaluation (Johnson et al, 2012 ; Jones et al, 2012 ).…”

Section: Introductionmentioning

confidence: 99%

Genetic characterization of clinical and environmental Vibrio parahaemolyticus from the Northeast USA reveals emerging resident and non-indigenous pathogen lineages

Ilyas

Hall

et al. 2015

Front. Microbiol.

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Gastric infections caused by the environmentally transmitted pathogen, Vibrio parahaemolyticus, have increased over the last two decades, including in many parts of the United States (US). However, until recently, infections linked to shellfish from the cool northeastern US waters were rare. Cases have risen in the Northeast, consistent with changes in local V. parahaemolyticus populations toward greater abundance or a shift in constituent pathogens. We examined 94 clinical isolates from a period of increasing disease in the region and compared them to 200 environmental counterparts to identify resident and non-indigenous lineages and to gain insight into the emergence of pathogenic types. Genotyping and multi-locus sequence analysis (MLSA) of clinical isolates collected from 2010 to 2013 in Massachusetts, New Hampshire, and Maine revealed their polyphyletic nature. Although 80% of the clinical isolates harbored the trh hemolysin either alone or with tdh, and were urease positive, 14% harbored neither hemolysin exposing a limitation for these traits in pathogen detection. Resident sequence type (ST) 631 strains caused seven infections, and show a relatively recent history of recombination with other clinical and environmental lineages present in the region. ST34 and ST674 strains were each linked to a single infection and these strain types were also identified from the environment as isolates harboring hemolysin genes. Forty-two ST36 isolates were identified from the clinical collection, consistent with reports that this strain type caused a rise in regional infections starting in 2012. Whole-genome phylogenies that included three ST36 outbreak isolates traced to at least two local sources demonstrated that the US Atlantic coastal population of this strain type was indeed derived from the Pacific population. This study lays the foundation for understanding dynamics within natural populations associated with emergence and invasion of pathogenic strain types in the region.

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The Trend of Vibrio parahaemolyticus Infections in Southern Thailand from 2006 to 2010

Cited by 33 publications

References 17 publications

Epidemiological Evidence of Lesser Role of Thermostable Direct Hemolysin (TDH)–Related Hemolysin (TRH) Than TDH onVibrio parahaemolyticusPathogenicity

Epidemiological Evidence of Lesser Role of Thermostable Direct Hemolysin (TDH)–Related Hemolysin (TRH) Than TDH onVibrio parahaemolyticusPathogenicity

Characterization of trh2 Harbouring Vibrio parahaemolyticus Strains Isolated in Germany

Genetic characterization of clinical and environmental Vibrio parahaemolyticus from the Northeast USA reveals emerging resident and non-indigenous pathogen lineages

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