Abstract
Vibrio parahaemolyticus causes the most seafood-attributed gastroenteritis outbreaks worldwide and studies on its pathogenesis during passage through the human digestive fluids are limited. An in vitro continuous model system mimicking passage through saliva, gastric and intestinal fluid was used to study the survival, morphology and virulence-related gene expression of a total of sixty pathogenic, and non-pathogenic V. parahaemolyticus strains. The changes to these three characteristics for the sixty V. parahaemolyticus strains were minimal on passage through the saliva fluid. No V. parahaemolyticus strains survived passage through gastric fluid with low pH values (2.0 and 3.0) and the cells, examined microscopically, were severely damaged. However, when the pH of gastric fluid increased to 4.0, the bacterial survival rate was 54.70 ± 1.11%, and the survival rate of pathogenic strains was higher when compared to non-pathogenic strains. Even though the bactericidal effect of intestinal fluid was lower than gastric fluid, virulence-related gene expression was enhanced in the intestinal fluid. Seafood matrices can significantly raise the pH level of gastric fluid and thus aid the survival of V. parahaemolyticus through passage from human gastric acid and progression of pathogenesis in the intestinal fluid. We confirmed these phenomena in the in vitro continuous digestion model.
Highlights
Vibrio parahemolyticus is the most common foodborne pathogen found in the marine and estuarine environment (Robert et al, 1969)
None of the sixty V. parahaemolyticus isolates could survive in the simulated gastric fluid (SGF) of pH 2.0 and 3.0, while 75% of isolates were still viable at pH 4.0 (Figure 2C)
This study mainly focused on the survival, morphological changes and virulence gene expression of V. parahaemolyticus in simulated digestive fluids
Summary
Vibrio parahemolyticus is the most common foodborne pathogen found in the marine and estuarine environment (Robert et al, 1969). Consumption of raw or undercooked seafood contaminated with high numbers of this bacterium causes acute gastroenteritis and serious septicemia (McLaughlin et al, 2005). Pathogenesis of Vibrio parahaemolyticus sequence homology (68%) where these toxins show betahemolytic activity on Wagatsuma agar and both show cytotoxicity ad enterotoxicity (Takeshi et al, 1990; Ohnishi et al, 2011). A type III secretion system (T3SS), which can utilize a needle-like apparatus to translocate effectors into the host cells, contributes to the virulence of V. parahaemolyticus (Ham and Orth, 2012; Zhang and Orth, 2013). T3SS2 is associated with cytotoxicity in intestinal cells and enterotoxicity in infected animal models (Ham and Orth, 2012). There is limited information of the pathogenesis of V. parahaemolyticus through passage in the human digestive tract
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