Brazilian urease-positive strains of Vibrio parahaemolyticus carry genetic potential to produce the TDH-related hemolysin

Magalhães, Marcelo; Takeda, Yasuharu; Magalhäes, Vera; Tateno, Seiki

doi:10.1590/s0074-02761992000100027

Cited by 15 publications

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“…We previously reported that the urease production by clinical V. parahaemolyticus strains correlates completely with the possession of the trh gene, and research by others has shown similar results (26,36,37). We have also found that the distance between the two genes is within several kilobases (17,18), suggesting the genetic linkage between the two genes.…”

Section: Discussionmentioning

confidence: 55%

“…In common with other Vibrio species, generally only a small population (several percent) of clinical V. parahaemolyticus strains produce urease (7,13,16,46). The relatively rare urease-positive phenotype of V. parahaemolyticus is always associated with the possession of the trh gene (26,36,37,46), making urease production a reasonably good clinical diagnostic marker for virulent (trhpositive) V. parahaemolyticus (46). Our previous research has shown that the association is due to a genetic linkage between the structural gene for urease (ureC) and trh on the chromosome of virulent V. parahaemolyticus strains (17).…”

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confidence: 99%

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Genetic Characterization of DNA Region Containing the trh and ure Genes of Vibrio parahaemolyticus

et al. 2000

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We have demonstrated that possession of the gene for thermostable direct hemolysin-related hemolysin (trh) coincides with the presence of the urease gene among clinical Vibrio parahaemolyticus strains and that the location of the two genes are in close proximity on the chromosome. Here, we cloned and sequenced the 15,754-bp DNA region containing the trh gene and the gene cluster for urease production from the chromosome of clinical V. parahaemolyticus (TH3996). We found 16 open reading frames (ORFs) and a lower G؉C content (41%) compared with the total genome of this bacterium (46 to 47%). The ure cluster consisted of eight genes, namely, ureDABCEFG and ureR. ureR was located 5.2 kb upstream of the other seven genes in the opposite direction. The genetic organization and sequences of the ure genes resembled those found in Proteus mirabilis. Between ureR and the other ure genes, there were five ORFs, which are homologous with the nickel transport operon (nik) of Escherichia coli. We disrupted each of the ureR, ureC, and nikD genes in TH3996 by homologous recombination and analyzed the phenotype of the mutants. In the presence of urea these mutant strains had dramatically less urease activity than the strain they were derived from. Disruption of ureR, nikD, or ureC, however, had no effect on TRH production. The DNA region containing the trh, nik, and ure genes was found in only trh-positive strains and not in Kanagawa phenomenon-positive and environmental V. parahaemolyticus strains. At the end of the region, an insertion sequence-like element existed. These results suggest that the DNA region was introduced into V. parahaemolyticus in the past through a mechanism mediated by insertion sequences. This is the first reported case that the genes for an ATP-binding cassette-type nickel transport system, which may play a role in nickel transport through bacterial cytoplasmic membrane, are located adjacent to the ure cluster on the genome of an organism.Vibrio parahaemolyticus is a gram-negative, halophilic marine bacterium which causes gastroenteritis in humans who are infected through consumption of raw or inadequately cooked seafood (15). V. parahaemolyticus strains that are isolated from diarrheal patients produce either the thermostable direct hemolysin (TDH) or the TDH-related hemolysin (TRH), or both, while hardly any isolates from the environment have these properties (15, 41). TDH and TRH, encoded by tdh and trh, respectively, are each composed of 165-amino-acid residues and show approximately 67% identity in their amino acid sequences. TDH and TRH show several common biological activities, such as hemolytic activity, enterotoxicity, cytotoxicity, and cardiotoxicity, and are considered to be the major virulence factors in the pathogenesis of V. parahaemolyticus (15,35,41,47).Urease is an enzyme that catalyzes the hydrolysis of urea to ammonia and carbon dioxide. It is found in a number of bacteria, plants, fungi, and algae (29). Several bacterial urease genes have been isolated and characterized. The types of o...

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Section: Discussionmentioning

confidence: 55%

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confidence: 99%

Genetic Characterization of DNA Region Containing the trh and ure Genes of Vibrio parahaemolyticus

et al. 2000

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“…1; also see Table S1 in the supplemental material). Strains positive for tdh, trh, and ureR have been persistently isolated from the west coast of the United States since 1979 (1,30,32,43,48), and the presence of urease has been suggested as a predictor of potential pathogenic isolates in the PNW (29) and several other geographic locations (35,45,51,56).…”

Section: Resultsmentioning

confidence: 99%

Genetic Diversity of Clinical and Environmental Vibrio parahaemolyticus Strains from the Pacific Northwest

Paranjpye

Hamel

Stojanovski

et al. 2012

Appl Environ Microbiol

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Since 1997, cases of Vibrio parahaemolyticus-related gastroenteritis from the consumption of raw oysters harvested in Washington State have been higher than historical levels. These cases have shown little or no correlation with concentrations of potentially pathogenic V. parahaemolyticus (positive for the thermostable direct hemolysin gene, tdh) in oysters, although significant concentrations of tdh ؉ V. parahaemolyticus strains were isolated from shellfish-growing areas in the Pacific Northwest (PNW). We compared clinical and environmental strains isolated from the PNW to those from other geographic regions within the United States and Asia for the presence of virulence-associated genes, including the thermostable direct hemolysin (tdh), the thermostable-related hemolysin (trh), urease (ureR), the pandemic group specific markers orf8 and toxRS, and genes encoding both type 3 secretion systems (T3SS1 and T3SS2). The majority of clinical strains from the PNW were positive for tdh, trh, and ureR genes, while a significant proportion of environmental isolates were tdh ؉ but trh negative. Hierarchical clustering grouped the majority of these clinical isolates into a cluster distinct from that including the pandemic strain RIMD2210633, clinical isolates from other geographical regions, and tdh ؉ , trh-negative environmental isolates from the PNW. We detected T3SS2-related genes (T3SS2␤) in environmental strains that were tdh and trh negative. The presence of significant concentrations of tdh ؉ , trhnegative environmental strains in the PNW that have not been responsible for illness and T3SS2␤ in tdh-and trh-negative strains emphasizes the diversity in this species and the need to identify additional virulence markers for this bacterium to improve risk assessment tools for the detection of this pathogen.

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“…Moreover, V. parahaemolyticus infections have increased globally 28,33 . Studies in Brazil demonstrated the presence of V. parahaemolyticus in environmental samples from a variety of sources as well as in clinical samples 1,25,26,27,31,34,35,38 . In 2002, according to data of the National Health Foundation (FUNASA), in Ceará, Brazil, an outbreak of gastroenteritis occurred, and Kanagawa-positive strains of V. parahaemolyticus serovar O3:K6 were isolated 31 .…”

Section: Introductionmentioning

confidence: 99%

Characterization of Vibrio Parahaemolyticus isolated from oysters and mussels in São Paulo, Brazil

Rojas

Matté

Dropa

et al. 2011

Rev. Inst. Med. trop. S. Paulo

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SUMMARYVibrio parahaemolyticus is a marine bacterium, responsible for gastroenteritis in humans. Most of the clinical isolates produce thermostable direct hemolysin (TDH) and TDH-related hemolysin (TRH) encoded by tdh and trh genes respectively. In this study, twenty-three V. parahaemolyticus, previously isolated from oysters and mussels were analyzed by PCR using specific primers for the 16S rRNA and virulence genes (tdh, trh and tlh) and for resistance to different classes of antibiotics and PFGE. Nineteen isolates were confirmed by PCR as V. parahaemolyticus. The tlh gene was present in 100% of isolates, the tdh gene was identified in two (10.5%) isolates, whereas the gene trh was not detected. Each isolate was resistant to at least one of the nine antimicrobials tested. Additionally, all isolates possessed the bla TEM-116 gene. The presence of this gene in V. parahaemolyticus indicates the possibility of spreading this gene in the environment. Atypical strains of V. parahaemolyticus were also detected in this study.

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Brazilian urease-positive strains of Vibrio parahaemolyticus carry genetic potential to produce the TDH-related hemolysin

Cited by 15 publications

References 0 publications

Genetic Characterization of DNA Region Containing the trh and ure Genes of Vibrio parahaemolyticus

Genetic Characterization of DNA Region Containing the trh and ure Genes of Vibrio parahaemolyticus

Genetic Diversity of Clinical and Environmental Vibrio parahaemolyticus Strains from the Pacific Northwest

Characterization of Vibrio Parahaemolyticus isolated from oysters and mussels in São Paulo, Brazil

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