Cause Of Seafood-borne Illness Research Articles

Nested Spatial and Temporal Modeling of Environmental Conditions Associated With Genetic Markers of Vibrio parahaemolyticus in Washington State Pacific Oysters.

The Pacific Northwest (PNW) is one of the largest commercial harvesting areas for Pacific oysters (Crassostrea gigas) in the United States. Vibrio parahaemolyticus, a bacterium naturally present in estuarine waters accumulates in shellfish and is a major cause of seafood-borne illness. Growers, consumers, and public-health officials have raised concerns about rising vibriosis cases in the region. Vibrio parahaemolyticus genetic markers (tlh, tdh, and trh) were estimated using an most-probable-number (MPN)-PCR technique in Washington State Pacific oysters regularly sampled between May and October from 2005 to 2019 (N = 2,836); environmental conditions were also measured at each sampling event. Multilevel mixed-effects regression models were used to assess relationships between environmental measures and genetic markers as well as genetic marker ratios (trh:tlh, tdh:tlh, and tdh:trh), accounting for variation across space and time. Spatial and temporal dependence were also accounted for in the model structure. Model fit improved when including environmental measures from previous weeks (1-week lag for air temperature, 3-week lag for salinity). Positive associations were found between tlh and surface water temp, specifically between 15 and 26°C, and between trh and surface water temperature up to 26°C. tlh and trh were negatively associated with 3-week lagged salinity in the most saline waters (> 27 ppt). There was also a positive relationship between tissue temperature and tdh, but only above 20°C. The tdh:tlh ratio displayed analogous inverted non-linear relationships as tlh. The non-linear associations found between the genetic targets and environmental measures demonstrate the complex habitat suitability of V. parahaemolyticus. Additional associations with both spatial and temporal variables also suggest there are influential unmeasured environmental conditions that could further explain bacterium variability. Overall, these findings confirm previous ecological risk factors for vibriosis in Washington State, while also identifying new associations between lagged temporal effects and pathogenic markers of V. parahaemolyticus.

Phylogenetic and Biogeographic Patterns of Vibrio parahaemolyticus Strains from North America Inferred from Whole-Genome Sequence Data.

Vibrio parahaemolyticus is the most common cause of seafood-borne illness reported in the United States. The draft genomes of 132 North American clinical and oyster V. parahaemolyticus isolates were sequenced to investigate their phylogenetic and biogeographic relationships. The majority of oyster isolate sequence types (STs) were from a single harvest location; however, four were identified from multiple locations. There was population structure along the Gulf and Atlantic Coasts of North America, with what seemed to be a hub of genetic variability along the Gulf Coast, with some of the same STs occurring along the Atlantic Coast and one shared between the coastal waters of the Gulf and those of Washington State. Phylogenetic analyses found nine well-supported clades. Two clades were composed of isolates from both clinical and oyster sources. Four were composed of isolates entirely from clinical sources, and three were entirely from oyster sources. Each single-source clade consisted of one ST. Some human isolates lack tdh, trh, and some type III secretion system (T3SS) genes, which are established virulence genes of V. parahaemolyticus Thus, these genes are not essential for pathogenicity. However, isolates in the monophyletic groups from clinical sources were enriched in several categories of genes compared to those from monophyletic groups of oyster isolates. These functional categories include cell signaling, transport, and metabolism. The identification of genes in these functional categories provides a basis for future in-depth pathogenicity investigations of V. parahaemolyticusIMPORTANCEVibrio parahaemolyticus is the most common cause of seafood-borne illness reported in the United States and is frequently associated with shellfish consumption. This study contributes to our knowledge of the biogeography and functional genomics of this species around North America. STs shared between the Gulf Coast and the Atlantic seaboard as well as Pacific waters suggest possible transport via oceanic currents or large shipping vessels. STs frequently isolated from humans but rarely, if ever, isolated from the environment are likely more competitive in the human gut than other STs. This could be due to additional functional capabilities in areas such as cell signaling, transport, and metabolism, which may give these isolates an advantage in novel nutrient-replete environments such as the human gut.

A Case-Control Analysis of Traceback Investigations for Vibrio parahaemolyticus Infections (Vibriosis) and Pre-harvest Environmental Conditions in Washington State, 2013-2018

Background/Aim: Vibrio parahaemolyticus is a major cause of seafood-borne illness. It is naturally prevalent in brackish waters and accumulates in shellfish. Vibriosis cases are rising globally, likely due to warming temperatures. We aimed to identify pre-harvest risk factors of vibriosis in Washington State using environmental and genetic variables sampled from shellfish. Methods: Successful traceback investigations of vibriosis were spatiotemporally matched to routine intertidal oyster (Crassostrea gigas) sampling events, which included measurements of temperature, salinity, and V. parahaemolyticus genetic targets. Remaining sampling events were treated as controls. Ecological variable importance was assessed using logistic regression models. Results: Systematic differences were observed across Washington harvesting zones. These included positive associations between the odds of vibriosis and genetic targets in South Puget Sound, with a particularly high odds ratio (OR) = 13.0 (95% CI: 1.5, 115.0) for a 1-log10 increase in the tdh pathogenic marker when total bacterium abundance was low (<1 log10). A positive association also occurred for a 1°C increase in tissue temperature OR=1.20 (95% CI: 1.10, 1.30) while a negative association occurred for a similar increase in water temperature OR= 0.70 (95% CI: 0.59, 0.81). The coastal bays displayed positive associations for water temperature OR= 2.16 (95% CI: 1.15, 4.05), and for a 1-log10 increase in the tdh:trh pathogenic marker ratio OR= 5.85 (95% CI: 1.06, 32.26). Conclusions: The zonal variation in associations indicates unique pathogenic strain prominence, suggesting tdh+/trh+ strains in South Puget Sound, such as the O4:K12 serotype, and tdh+/trh- strains in the coastal bays. The temperature discrepancy between water and oyster tissue suggests that South Puget Sound pathogenic strains flourish with exposure to relatively warm air during low tide. These findings identify new ecological risk factors for vibriosis in Washington State that can be used in future prevention efforts.

A case-control analysis of traceback investigations for Vibrio parahaemolyticus infections (vibriosis) and pre-harvest environmental conditions in Washington State, 2013–2018

BackgroundVibrio parahaemolyticus is a major cause of seafood-borne illness. It is naturally prevalent in brackish waters and accumulates in shellfish. Vibriosis cases are rising globally, likely due to rising temperatures. ObjectivesTo identify associations between vibriosis in Washington State and pre-harvest environmental and V. parahaemolyticus genetic measurements sampled from shellfish. MethodsSuccessful vibriosis traceback investigations were spatiotemporally matched to routine intertidal oyster (Crassostrea gigas) sampling events, which included measurements of temperature, salinity, and V. parahaemolyticus genetic targets (thermolabile hemolysin: tlh; thermostable direct hemolysin: tdh; thermostable direct-related hemolysin: trh). Unmatched sampling events were treated as controls. Associations were evaluated using logistic regression models. ResultsSystematic differences were observed across Washington harvesting zones. These included positive associations between the odds of vibriosis and all three genetic targets in South Puget Sound, with a large odds ratio (OR) = 13.0 (95% CI: 1.5, 115.0) for a 1-log10 increase in tdh when total bacterium abundance was low (tlh < 1 log10 MPN/g). A positive association also occurred for a 1 °C increase in tissue temperature OR = 1.20 (95% CI: 1.10, 1.30) while a negative association occurred for a similar increase in water temperature OR = 0.70 (95% CI: 0.59, 0.81). In contrast, the coastal bays displayed positive associations for water temperature OR = 2.16 (95% CI, 1.15, 4.05), and for a 1-log10 increase in the tdh:trh ratio OR = 5.85 (95% CI, 1.06, 32.26). DiscussionThe zonal variation in associations indicates unique pathogenic strain prominence, suggesting tdh+/trh+ strains in South Puget Sound, such as the O4:K12 serotype, and tdh+/trh− strains in the coastal bays. The temperature discrepancy between water and oyster tissue suggests that South Puget Sound pathogenic strains flourish with exposure to relatively warm air during low tide. These findings identify new ecological risk factors for vibriosis in Washington State that can be used in future prevention efforts.

Associations of Environmental Conditions and Vibrio parahaemolyticus Genetic Markers in Washington State Pacific Oysters.

Vibrio parahaemolyticus is a naturally occurring bacterium in estuarine waters and is a major cause of seafood-borne illness. The bacterium has been consistently identified in Pacific Northwest waters and elevated illness rates of vibriosis in Washington State have raised concerns among growers, risk managers, and consumers of Pacific oysters (Crassostrea gigas). In order to better understand pre-harvest variation of V. parahaemolyticus in the region, abundance of total and potentially pathogenic strains of the bacterium in a large number of Washington State Pacific oyster samples were compared with environmental conditions at the time of sampling. The Washington Department of Health regularly sampled oysters between June and September at over 21 locations from 2014 to 2018, resulting in over 946 samples. V. parahaemolyticus strains carrying three genetic markers, tlh, trh, and tdh, were enumerated in oyster tissue using a most probable number-PCR analysis. Tobit regressions and seemingly unrelated estimations were used to formally assess relationships between environmental measures and genetic markers. All genetic markers were found to be positively associated with temperature, independent of the abundance of other genetic markers. Surface water temperature displayed a non-linear relationship, with no association observed between any genetic marker in the warmest waters. There were also stark differences between surface and shore water temperature models. Salinity was not found to be substantially associated with any of the genetic variables. The relative abundance of tdh+ strains given total V. parahaemolyticus abundance (pathogenic ratio tdh:tlh) was negatively associated with water temperature in colder waters and decreased exponentially as total V. parahaemolyticus abundance increased. Strains carrying the trh gene had a pronounced positive association with strains carrying the tdh gene but was also negatively associated with the tdh:tlh pathogenic ratio. These results suggest that there are ecological relationships of competition, growth, and survival for V. parahaemolyticus strains in the oyster tissue matrix. This work also improves the overall understanding of environmental associations with V. parahaemolyticus in Washington State Pacific oysters, laying the groundwork for future risk mitigation efforts in the region.

Multiplex qPCR Detection of Nonpathogenic and Pathogenic Vibrio parahaemolyticus and Vibrio vulnificus from Oysters Cultured in Massachusetts and Rhode Island: The Reliability of MPN as an Indicator

The leading cause of seafood-borne illness in the United States is Vibrio parahaemolyticus, whereas Vibrio vulnificus has the highest case fatality rate from wound infections of any foodborne pathogen. The Food and Drug Administration (FDA) uses a method of bacterial determination in oyster tissues termed “most probable number” (MPN) to enumerate Vibrio spp. abundance. This study used the development of two multiplex qPCR methods for the enumeration of total and pathogenic V. parahaemolyticus and V. vulnificus in oyster tissue using plasmid controls. Oysters, Crassostrea virginica, were collected from aquaculture farms in Wareham, MA, and Portsmouth, RI, from May to October 2014. Food and Drug Administration MPN and MPN-qPCR methods were compared and showed that FDA methods had higher values for both locations than MPN-qPCR methods. Throughout the summer at both locations, V. parahaemolyticus was most abundant with a majority being trh⁺ strains. Although serotypes were not directly tested for, tdh⁺ and trh⁺ strains were identified, suggesting a low possible occurrence of O4: K12 and no possible occurrence of O3:K6. In some samples, Vibrio alginolyticus was detected, indicating that trh⁺ percentages may be attributed to either V. parahaemolyticus or V. alginolyticus because of the similarity of the trh gene. The results from this study indicate the poor specificity and quantifiability of the FDA MPN method. This work also demonstrated that the use of plasmid controls for routine molecular methods to be used in a laboratory provided a reliable and consistent source of positive controls to compare against unknown samples for the abundance of V. parahaemolyticus and V. vulnificus.

Spatial and Temporal Characteristics of Vibrio Parahaemolyticus in the Chesapeake Bay

Vibrio parahaemolyticus naturally occurs in estuaries and is a leading cause of seafood-borne illness. It is therefore necessary to develop ecological prediction tools for shellfish harvesting waters. Such predictions need adequate spatial and temporal resolution as bacterium abundance fluctuates frequently.Previous work identified environmental determinants of V. parahaemolyticus in the tidal waters of the Chesapeake Bay using a large data set (n&amp;#61; 1,385) collected from 148 monitoring stations between 2007-2010. Regression models were developed using water samples analyzed by qPCR along with spatially- and temporally-indexed water quality data. Previously identified relationships with temperature and turbidity were confirmed, while more complex relationships were identified for nitrogen and phosphorus. Non-linear associations with salinity were determined to be a function of both low temperature and turbidity.Recent work attempted to develop V. parahaemolyticus prediction models using time-indexed and 1- and 2-month lagged water quality measures. Tobit regression models were evaluated using cross-validation methods to quantify prediction bias and uncertainty. The results were promising, indicating that water quality data can provide adequate prediction for bacterium presence and abundance, and that lagged measures provide complimentary or superior predictive power when compared to time-indexed measures.Current work is expanding variable selection for prediction models and increase the spatial-temporal extent of such predictions by using geostatistical interpolation techniques. These modeling efforts will culminate in a prediction tool that will provide real-time forecasts of V. parahaemolyticus. These prediction models will better inform shellfish harvesters and regulators on when and where preventative food safety post-harvesting practices are necessary.

Characterizing the Adherence Profiles of Virulent Vibrio parahaemolyticus Isolates.

The human pathogen Vibrio parahaemolyticus is a leading cause of seafood-borne illness in the USA, and infections with V. parahaemolyticus typically result from eating raw or undercooked oysters. V. parahaemolyticus has been shown to be highly resistant to oyster depuration, suggesting that the bacterium possesses specific mechanisms or factors for colonizing oysters and persisting during depuration. In this study, we characterized eight different V. parahaemolyticus strains for differences in resistance to oyster depuration, biofilm formation, and motility. While each strain exhibited distinct phenotypes in the various assays, we determined that biofilm formation on abiotic surfaces, such as glass or plastic, does not directly correlate with bacterial retention in oysters during depuration. However, we did observe that the motility phenotype of a strain appeared to be a better indicator for persistence in the oyster. Further studies examining the molecular mechanisms underlying the observed colonization differences by these and other V. parahaemolyticus strains may provide beneficial insights into what critical factors are required for proficient colonization of the Pacific oyster.

Prevalence and antimicrobial susceptibility of Vibrio parahaemolyticus isolated from retail shellfish in Shanghai

Vibrio parahaemolyticus is a marine and estuarine bacterium that poses the greatest threat to human health worldwide. It has been the leading bacterial cause of seafood-borne illness. This study investigated the prevalence and drug resistance of V. parahaemolyticus isolated from retail shellfish in Shanghai. A total of 140 shellfish samples were collected from February 2014 to February 2015. The occurrence of V. parahaemolyticus in shellfish was 34.3%, which has increased compared to previous reports. In addition, discernible differences of total presumptive V. parahaemolyticus counts (TPVPC) were also observed in shellfish between market A and B. The results from PCR assays indicated that thermostable direct hemolysin (tdh) gene was positive in two isolates (2.1%), and the thermostable direct hemolysin-related hemolysin (trh) gene was not detected in all isolates. Antibiotic resistance profiles of those isolates were as follows: ampicillin (87.5%), cephazolin (31.3%), cephalothin (6.3%), amoxicillin/clavulanic acid (6.3%), piperacillin (6.3%), and amikacin (3.2%). Thirty-three out of 96 isolates were resistant to two or more antimicrobial agents. It is suggested that V. parahaemolyticus in retail shellfish could be a potential risk to consumers in Shanghai.

The Vibrio parahaemolyticus effector VopQ induces autophagosome accumulation in host cells

Vibrio parahaemolyticus, a Gram‐negative bacterium, is the leading cause of seafood‐borne illness in the United States. This pathogen is able to infect and survive in humans by manipulating the host cellular machinery via bacterial Type III effector proteins that are translocated into the host cell, where they disrupt cellular signaling. One of the principal effector proteins, VopQ, has been demonstrated to be necessary and sufficient to induce autophagosome accumulation. I propose to elucidate the precise cellular and molecular mechanism by which VopQ induces autophagosome accumulation. Since autophagosomes are transient vesicles, the accumulation could be due to an increase in formation of autophagosomes or a decrease in lysosomal fusion. Using biochemical assays and yeast genetics we have uncovered a novel target that reveals the role of VopQ in vesicle fusion during autophagy.With the discovery of several bacterial effectors that function to manipulate host membranes, many eukaryotic vesicle trafficking pathways have been unveiled, and many new questions have surfaced about the mechanisms of novel bacterial effectors. Understanding the mechanism by which VopQ induces autophagosome accumulation could be essential in understanding V. para infection and could give new insights into the mechanisms of eukaryotic vesicle trafficking.

The occurrence of Vibrio species in tropical shrimp culture environments; implications for food safety

The occurrence of various Vibrio species in water, sediment and shrimp samples from multiple shrimp farm environments from the east and west coast of India was studied. The relative abundance was higher in west coast farms (ca. 10 4 cfu/ml water) when compared to the east coast (ca. 10 2 cfu/ml water). Vibrio alginolyticus (3–19%), V. parahaemolyticus (2–13%), V. harveyi (1–7%) and V. vulnificus (1–4%) were the predominant Vibrio species identified by standard biochemical testing. In some cases, V. cholerae could be found, but all isolates were negative for the cholera toxin ( ctx) gene that is associated with choleragenic strains. The biochemical identification of V. parahaemolyticus, the other human pathogen among the species mentioned above, was confirmed by PCR targeting the toxR gene and a 387 bp chromosomal locus specific for this species. Furthermore, the presence of the virulence-associated tdh (thermostable direct haemolysin) and trh (TDH-related haemolysin) genes in the V. parahaemolyticus isolates was also detected by PCR. Only 2 out of 47 isolates were tdh positive and one contained the trh gene. However, since V. cholerae, V. parahaemolyticus and V. vulnificus species are recognized as a major cause of seafood-borne illness, it is important to pay attention to post-harvest handling and adequate cooking.