Consumption Of Oysters Research Articles

Effects of oxidation reduction potential levels on bacterial density in Portuguese oysters (Crassostrea angulata) utilising a sonoelectrochemical depuration system

ABSTRACT The consumption of raw oysters is on the rise and poses a significant health risk because of the presence of bacteria such as Escherichia coli, Salmonella spp., and Vibrio spp. Sonoelectrochemical technology offers a promising solution by creating nanobubbles charged with negative ions, which effectively kill bacteria in oysters without affecting human health, and is also environmentally friendly. This study evaluated the bacterial reduction capability of this technology on Portuguese oysters (Crassostrea angulata) using different oxidation redox potential (ORP) levels of 450, 600 and 750 mV compared with clean seawater (control) after 8, 16 and 24 hours. The results showed that extended exposure time did not significantly decrease E. coli and Salmonella spp. densities, except for the 750 mV treatment. The ORP level of 750 mV for 16 hours was the most effective in reducing bacterial population in oysters with total Vibrio, E. coli and Salmonella spp. reduced by 1.14, 0.95, and 0.85 logCFU/g, respectively. Further research is needed to optimise oyster depuration using sonoelectrochemical technology to enhance its efficiency and practical application.

Inhibition of Norovirus GII.4 binding to HBGAs by Sargassum fusiforme polysaccharide.

Norovirus (NoV) is the main pathogen that causes acute gastroenteritis and brings a heavy socio-economic burden worldwide. In this study, five polysaccharide fractions, labeled pSFP-1-5, were isolated and purified from Sargassum fusiforme (S. fusiforme). In vitro experiments demonstrated that pSFP-5 significantly prevented the binding of type A, B and H histo-blood group antigens (HBGAs) to NoV GII.4 virus-like particles (NoV GII.4 VLPs). In addition, in vivo experiments revealed that pSFP-5 was effective in reducing the accumulation of NoV in oysters, indicating that pSFP-5 could reduce the risk of NoV infection from oyster consumption. The results of transmission electron microscopy showed that the appearance of NoV GII.4 VLPs changed after pSFP-5 treatment, indicating that pSFP-5 may achieve antiviral ability by altering the morphological structure of the viral particles so that they could not bind to HBGAs. The results of the present study indicate that pSFP-5 may be an effective anti-NoV substance and can be used as a potential anti-NoV drug component.

Analysis of Cadmium, Mercury and Lead in oysters (Crassostrea virginica) in a protected area of southeastern Mexico associated with the risk to human health

BackgroundMetal pollution is a problem in many parts of the world. These metals can be harmful when they exceed the recommended limits. This study aimed to assess the levels of cadmium (Cd), mercury (Hg), and lead (Pb) in the tissues of oysters (Crassostrea virginica) within a protected area in southeastern Mexico. Additionally, the study aimed to conduct a risk analysis for human health associated with these metals. It is anticipated that the observed metal levels will be lower compared to prior studies, thereby not posing a significant risk to the local population. MethodsThe tissue of oyster samples was treated under the techniques of the Official Mexican Standards and analyzed using atomic absorption spectroscopy. The metal concentrations were used to calculate the estimated daily intakes (EDI), target hazard quotients (THQ), hazard index (HI), and target cancer risks (TR), for children and adults. ResultsMaximum values of Cd (1.99 μg g−1), exceeded the permissible limits of the Official Mexican Standards. Pb (0.99 μg g−1) and Hg (0.64 μg g−1) are within the recommended limits. The THQ and HI for Cd, Pb, and Hg were lower than the United States Environmental Protection Agency (US-EPA) criteria. ConclusionsBased on our results, whether oyster (Crassostrea virginica) consumption is recommended in adults and reducing consumption in children; to diminish the risk of exposure to Cd, Pb, and Hg.

Pharmaceutical Residues in Edible Oysters along the Coasts of the East and South China Seas and Associated Health Risks to Humans and Wildlife.

The investigation of pharmaceuticals as emerging contaminants in marine biota has been insufficient. In this study, we examined the presence of 51 pharmaceuticals in edible oysters along the coasts of the East and South China Seas. Only nine pharmaceuticals were detected. The mean concentrations of all measured pharmaceuticals in oysters per site ranged from 0.804 to 15.1 ng g-1 of dry weight, with antihistamines being the most common. Brompheniramine and promethazine were identified in biota samples for the first time. Although no significant health risks to humans were identified through consumption of oysters, 100-1000 times higher health risks were observed for wildlife like water birds, seasnails, and starfishes. Specifically, sea snails that primarily feed on oysters were found to be at risk of exposure to ciprofloxacin, brompheniramine, and promethazine. These high risks could be attributed to the monotonous diet habits and relatively limited food sources of these organisms. Furthermore, taking chirality into consideration, chlorpheniramine in the oysters was enriched by the S-enantiomer, with a relative potency 1.1-1.3 times higher when chlorpheniramine was considered as a racemate. Overall, this study highlights the prevalence of antihistamines in seafood and underscores the importance of studying enantioselectivities of pharmaceuticals in health risk assessments.

The Usage of an AMCA-Modified Aptamer Facilitates the Rapid Detection of Vibrio vulnificus

Background: Vibrio vulnificus can cause serious infections in human beings associated with the consumption of raw oysters or cuts exposed to seawater. The traditional method for culturing V. vulnificus is time-consuming and has a high failure rate. Objectives: This study aims to detect V. vulnificus using an AMCA-modified specific DNA aptamer. Methods: Common pathogenic microorganisms present in the seawater of the Fujian Sea area were collected, cultured, and identified. The samples were found to contain mainly V. vulnificus, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, V. alginolyticus, V. parahaemolyticus, and V. cholerae. AMCA was conjugated with 5’ ends of the aptamer using N-hydroxysuccinimide ester (NHS ester) to target V. vulnificus and produce a fluorescent signal upon binding. The aptamer was screened and optimized for rapid detection of V. vulnificus. We collected the 50 bacterial strains isolated from clinical secretion samples and used a fluorescence microscope to determine whether the sample contained V. vulnificus or not. We compared these results with those obtained from VITEK MS (considered the gold standard) to test the sensitivity and specificity of the AMCA-modified aptamer using IBM SPSS Statistics 22. Results: In this experiment, the sensitivity and specificity of the modified aptamer for detecting V. vulnificus were determined to be 100% [95% CI (0.39, 1)] and 93.4% [95% CI (0.81, 0.98)], respectively. The positive predictive value was 57% [95% CI (0.20, 0.88)], and the negative predictive value was 100% [95% CI (0.89, 1)]. These findings indicate that V. vulnificus specimens can be rapidly detected via fluorescence reaction within 30 minutes. Conclusions: Our results suggest that this modified DNA aptamer has the potential to be used for diagnosing V. vulnificus. Further research is needed to explore the application of aptamers in pathogen infections.

The archaeology of 19th century oyster consumption in Melbourne

ABSTRACTThis paper presents comparative research on marine shell from four 19th century historical archaeological sites in Melbourne. The shell derives predominantly from Mud Oyster (Ostrea angasi) and Sydney Rock Oyster (Saccostrea glomerata) commercially harvested from natural reefs along the south‐east Australian coastline. The research collects quantitative data that informs on the 19th century oyster industry and investigates inter‐site shell variability and its implications for processing, consumption and discard. Dredging of subtidal reefs provides an explanation for the numerical dominance of oyster, the presence of subfossil cultch (Anadara) and the wide range of minor shellfish. Mud oyster and Sydney rock oyster comparisons in valve size, sided counts and preservation record significant differences within and between sites due to the origins, depositional conditions and the processing of the shell. These data form the basis of two models. The first predicts the archaeological representation of reef dredging and ranks shellfish according to categories, from live oysters to dead shell sampled from the reef substrate. Based on oyster shell anatomy and the separate uses of the right (lid) and left (dish) valves, the second model considers how oyster processing and consumption is characterised archaeologically in differential valve counts and pairing rates.

Explainable machine learning for predicting the geographical origin of Chinese Oysters via mineral elements analysis

The traceability of geographic origin is essential for guaranteeing the quality, safety, and protection of oyster brands. However, the current outcomes of traceability lack credibility as they do not adequately explain the model's predictions. Consequently, we conducted a study to evaluate the efficacy of utilizing explainable machine learning combined with mineral elements analysis. The study findings revealed that 18 elements have the ability to determine regional orientation. Simultaneously, individuals should pay closer attention to the potential risks associated with oyster consumption due to the regional differences in essential and toxic elements they contain. Light gradient boosting machine (LightGBM) model exhibited indistinguishable performance, achieving flawless accuracy, precision, recall, F1 score and AUC, with values of 96.77%, 96.43%, 98.53%, 97.32% and 0.998, respectively. The SHapley Additive exPlanations (SHAP) method was used to evaluate the output of the LightGBM model, revealing differences in feature interactions among oysters from different provinces. Specifically, the features Na, Zn, V, Mg, and K were found to have a significant impact on the predictive process of the model. Consistent with existing research, the use of explainable machine learning techniques can provide insights into the complex connections between important product attributes and relevant geographical information.

Spatial Distribution and Enrichment Dynamics of Foodborne Norovirus in Oyster Tissues.

The prevalence of norovirus in oysters poses a significant threat to food safety, necessitating a comprehensive understanding of contamination patterns. This study explores the temporal dynamics of norovirus distribution in various oyster tissues over a contamination period ranging from 6 to 96 h. Four tissues-the gill, palp, digestive gland, and stomach-were subjected to systematic monitoring using RT-qPCR for absolute quantification. Results revealed rapid norovirus detection in all tissues six hours post-contamination, with subsequent variations in detection rates. Gill and digestive gland tissues exhibited a peak in detection at 12-24 h, aligning with the oyster's gastrointestinal circulatory system. The digestive gland, distinguished by specific enrichment and adsorption capabilities, demonstrated the highest virus concentration at 48 h. In contrast, the stomach displayed a reemergence of norovirus. Beyond 72 h, detection remained exclusive to the digestive gland, with Ct values comparable to earlier time points. At 96 h, a limited amount of norovirus was detected in the digestive gland, emphasizing the importance for timely monitoring. In addition to providing critical insights into optimal detection strategies, these findings highlight the time-related characteristics of norovirus contamination in oysters. The study identifies the digestive gland as a key target for reliable monitoring, providing valuable data to improve protocols for reducing hazards associated with oyster consumption and foodborne norovirus infections. This research contributes to the understanding of norovirus dynamics in oyster tissues and reinforces current efforts aimed at ensuring food safety and public health.

Evaluation of Heavy Metal Pollution in Commonly Consumed Mollusc (Crassostrea gasar) from Elechi Creek, River State, Nigeria and the Health Risk Implications

Marine biotas are used to assess potential adverse human health risks associated with consuming protein-rich aquatic organisms. Heavy metal content of Mangrove oysters (Crassostrea gasar) was evaluated between January and June 2022 in 3 stations. Six heavy metals (copper, cadmium, zinc, lead, arsenic and iron) were determined using standard methods. Target Hazard Quotient (THQ) and Hazard Index (HI) were used for the non-carcinogenic assessment while Target Cancer Risk (TR) was used for the carcinogenic assessment of the potential human health risk of consuming the oysters. The heavy metal values recorded were Cu (473.2 – 596.7 mg/kg), Cd (2.33 – 3.84 mg/kg), 209.02 – 246.41 mg/kg), Pb (6.16 – 12.07 mg/kg), As (0.012 – 0.016 mg/kg) and Fe (1609.0 – 1846.0 mg/kg). All the heavy metals were above the acceptable limits except arsenic. Stations 2 and 3 had relatively higher values; attributed to anthropogenic activities. The THQ and HI values were less than 1 in all the metals and stations while TR for Pb and arsenic were within the negligible range in all the stations. However, Cd was unacceptable among the children in station 2. Station 3 had relatively higher values while the children were more vulnerable to both non-carcinogenic and carcinogenic risks. In conclusion, the consumption of oysters from Elechi Creek is considered safe based on acceptable levels of the THQ, HI and TR; though Cd-TR for children (Station 2) was unacceptable.

Comparative Description and Analysis of Oyster Aquaculture in Selected Atlantic Regions: Production, Market Dynamics, and Consumption Patterns

In the face of an increasing world population and a subsequent need for an increase in sustainable and healthy food production, low trophic species, such as oysters, emerge as a promising alternative. However, regional variations in oyster production techniques, market dynamics, and consumption patterns create challenges for both the global and local industry’s growth. In this study, a descriptive qualitative analysis of oyster markets across seven Atlantic regions was carried out. The Pacific oyster (Crassostrea gigas) was found to be farmed in most Atlantic regions except the US but is classified as invasive in Sweden and potentially invasive in South Africa. Other farmed and/or harvested species include native species (C. gasar and C. rhizophorae) in Brazil, the American cupped oyster (C. virginica) in the US, and the European flat oyster (Ostrea edulis) in France, Sweden, and the US. In Irish farms, Pacific oysters are primarily for export to European markets. The marine aquaculture sectors of Sweden, South Africa, and Namibia, as well as Brazil’s farming for C. gasar, were found to be underdeveloped. This study also observed a variation in licensing, property rights, and regulatory frameworks. Financial challenges for small businesses, ecological implications of seed production techniques, biosecurity risks, and public health considerations are emphasized as critical areas for attention. This study offers valuable insights into the selected markets and can serve as a useful resource for policymakers, aquaculture practitioners, and stakeholders in optimizing global shellfish industry strategies.

Pathogenetic detection, retrospective and pathogenicity analysis of a fatal case of Vibrio vulnificus in Shenzhen, China

We report a 36-year-old male patient died of V. vulnificus-induced septicaemia and multiple organ failure syndrome after oyster consumption at a restaurant. We isolated and identified V. vulnificus vv16015 from the patient’s blood sample and antibiotic susceptibility tests indicated sensitivity to all 21 antibiotics. Oyster samples were subsequently collected from the restaurant’s supplier and three strains of V. vulnificus were isolated. Whole genome sequencing and analysis revealed vv16015 to be distantly related to these strains and confirmed that V. vulnificus contamination was present in the seafood of the restaurant and supplier. Using a Galleria mellonella larvae infection model, the virulence of vv16015 was determined to be higher than that of comparison strains isolated from a surviving patient (vv15018) and an oyster (vv220015). The human and environment distribution of V. vulnificus in Shenzhen is sporadic and heterogeneous, and vv16015 is highly virulent compared to other strains.

Research Progress on Biological Accumulation, Detection and Inactivation Technologies of Norovirus in Oysters.

Noroviruses (NoVs) are major foodborne pathogens that cause acute gastroenteritis. Oysters are significant carriers of this pathogen, and disease transmission from the consumption of NoVs-infected oysters occurs worldwide. The review discusses the mechanism of NoVs bioaccumulation in oysters, particularly the binding of histo-blood group antigen-like (HBGA-like) molecules to NoVs in oysters. The review explores the factors that influence NoVs bioaccumulation in oysters, including temperature, precipitation and water contamination. The review also discusses the detection methods of NoVs in live oysters and analyzes the inactivation effects of high hydrostatic pressure, irradiation treatment and plasma treatment on NoVs. These non-thermal processing treatments can remove NoVs efficiently while retaining the original flavor of oysters. However, further research is needed to reduce the cost of these technologies to achieve large-scale commercial applications. The review aims to provide novel insights to reduce the bioaccumulation of NoVs in oysters and serve as a reference for the development of new, rapid and effective methods for detecting and inactivating NoVs in live oysters.

An overview of microplastics in oysters: Analysis, hazards, and depuration.

Microplastic pollution has become an emergent global environmental issue because of its ubiquitous nature and everlasting ecological impacts. In marine ecosystems, microplastics can serve as carriers to absorb various contaminants and the ingestion of microplastics in oysters is of concern because they can induce several adverse effects. The analytical process of microplastics in oysters commonly consists of separation, quantification, and identification. Quantification of microplastics is difficult since information regarding the analytical methods is incoherent, therefore, standard microplastic analytical methods for shellfish should be established in the future. The depuration process can be used to reduce the level of microplastics in oysters to ensure safe consumption of oysters and longer depuration time facilitates improved depuration efficacy. In summary, this review aims to help better understand microplastic pollution in oysters and provide useful suggestions and guidance for future research.

S3872 Vibrio vulnificus Septic Shock and Disseminated Intravascular Coagulation After Raw Oyster Consumption in a Patient With Cirrhosis

S3872 Vibrio vulnificus Septic Shock and Disseminated Intravascular Coagulation After Raw Oyster Consumption in a Patient With Cirrhosis

Duped by dumping syndrome: non-endemic Vibrio cholerae bacteremia in an immunocompetent host with gastric bypass surgery, a case report

Extra-intestinal infection with non-O1/non-O139 strains of Vibrio cholerae (NOVC) is rare, though bacteremia and hepatobiliary manifestations have been reported. Reduced stomach acid, or hypochlorhydria, can increase risk of V. cholerae infection. We describe a 42-year-old woman with hypochlorhydria due to untreated Helicobacter pylori infection, gastric-bypass surgery, and chronic proton pump inhibitors (PPI) exposure, who developed acute diarrhoea following raw oyster consumption. Her symptoms were attributed to rapid gastric emptying (dumping syndrome) after a negative limited stool work-up. She had persistent diarrhoea, weight loss, and after 5 months was admitted with acute cholecystitis and NOVC bacteremia, requiring cholecystectomy. This is the first reported case of NOVC bacteremia and cholecystitis in a patient with gastric bypass. This case highlights the potential for NOVC biliary carriage, the role of hypochlorhydria as a risk factor for Vibrio infection, and the importance of excluding infectious diarrhoea in patients with new onset of symptoms compatible with dumping syndrome and a relevant travel history.

Campylobacter jejuni Outbreak Linked to Raw Oysters in Rhode Island, 2021

Oysters and other shellfish are not a food that is commonly highlighted as high risk for Campylobacter contamination. The Rhode Island Department of Health (RIDOH) conducted a multiagency investigation of a Campylobacter jejuni outbreak that was linked to the consumption of raw oysters; the first such outbreak was detected in Rhode Island. The environmental investigation identified birds as the likely source of contamination of the aquacultured oysters. As a result of this outbreak response, several investigative processes and best practice recommendations are offered. 1) RIDOH will be including exposure to raw shellfish as a question on their case report forms to better identify future oyster-related Campylobacter clusters. 2) It is important that shellfish aquaculture farms be aware of the risks of using floating gear to hold oyster cages and of the importance of using bird abatement to keep birds off floating aquaculture gear to prevent contamination of oysters from bird feces. 3) It should be recognized that fecal coliform water samples collected near an oyster aquaculture farm may not act as an adequate indicator for the presence of Campylobacter. 4) For the first time, Rhode Island has developed guidelines for the closure and reopening of oyster harvest areas due to contamination with Campylobacter. It is hoped that increased awareness and mitigation of the described risk factors will help prevent future similar outbreaks of illness.

Mercury concentrations in sediments and oysters in a temperate coastal zone: a comparison of farmed and wild varieties.

Oyster aquaculture has progressively increased to meet growing demands for seafood worldwide; however, its effects on methylmercury (MeHg) production in sediment and accumulation in oysters are largely unknown. In this study, total Hg (THg) and MeHg in sediments collected from aquaculture and reference sites and in farmed and wild oysters were measured and compared to explore potential factors that regulate MeHg production and bioaccumulation at the aquaculture sites. The results showed that the mean concentrations of THg and MeHg in varying sediment depths at the aquaculture site were 34 ± 4.1 ng g-1 and 16 ± 12 pg g-1, respectively. In comparison, the mean concentrations of THg and MeHg in sediments at the reference site were 25 ± 2.5 ng g-1 and 63 ± 28 pg g-1, respectively. While the MeHg/THg in the aquaculture sediments increased with organic carbon content, the slope of MeHg/THg versus organic carbon content was suppressed by high concentrations of dissolved sulfide in the pore water. Multiple parameters (total sulfur, total nitrogen and acid volatile sulfide in sediment, and dissolved sulfide in pore water) showed significant negative relationships with MeHg/THg in the sediment, and the total sulfur content in the sediment showed the highest inverse correlation factor with MeHg/THg (r = - 0.83). The mean concentrations of THg and MeHg in farmed oysters (mean weight 3.2 ± 1.5 g) were 36 ± 10 ng g-1 and 15 ± 6.7 ng g-1, respectively, while those in wild oysters (mean weight 0.92 ± 0.32 g) were 47 ± 9.9 ng g-1 and 15 ± 6.7 ng g-1, respectively. Concerning oysters of the same size range, THg and MeHg levels were higher in farmed oysters than in wild oysters despite the faster growth rate of farmed oysters, suggesting that the Hg content of food sources is more important than growth dilution rates in the control of Hg levels. The mean hazardous quotient for MeHg in farmed oyster was calculated as 0.044 ± 0.020, suggesting no expected health risk from farmed oyster consumption.

Notes from the Field: Outbreak of Norovirus Illness Caused by Consumption of Oysters Harvested from Galveston Bay, Texas - November-December 2022.

Notes from the Field: Outbreak of Norovirus Illness Caused by Consumption of Oysters Harvested from Galveston Bay, Texas - November-December 2022.

Modelling norovirus dynamics within oysters emphasises potential food safety issues associated with current testing & depuration protocols

Norovirus is a significant global cause of viral gastroenteritis, with raw oyster consumption often linked to such outbreaks due to their filter-feeding in harvest waters. National water quality and depuration/relaying times are often classified using Escherichia coli, a poor proxy for norovirus levels in shellfish. The current norovirus assay is limited to only the digestive tracts of oysters, meaning the total norovirus load of an oyster may differ from reported results. These limitations motivated this work, building upon previous modelling by the authors, and considers the sequestration of norovirus into observed and cryptic (unobservable) compartments within each oyster. Results show that total norovirus levels in shellfish batches exhibit distinct peaks during the early depuration stages, with each peak's magnitude dependent on the proportion of cryptic norovirus. These results are supported by depuration trial data and other studies, where viral levels often exhibit multiphase decays. This work's significant result is that any future norovirus legislation needs to consider not only the harvest site's water classification but also the total viral load present in oysters entering the market. We show that 62 h of depuration should be undertaken before any norovirus testing is conducted on oyster samples, being the time required for cryptic viral loads to have transited into the digestive tracts where they can be detected by current assay, or have exited the oyster.

Integrating chemical and biological data by chemometrics to evaluate detoxification responses of a neotropical bivalve to metal and metalloid contamination

Mangroves represent a challenge in monitoring studies due to their physical and chemical conditions under constant marine and anthropogenic influences. This study investigated metals/metalloids whole-body bioaccumulation (soft tissues) and the risk associated with their uptake, biochemical and morphological detoxification processes in gills and metals/metalloids immobilisation in shells of the neotropical sentinel oyster Crassostrea rhizophorae from two Brazilian estuarine sites. Biochemical and morphological responses indicated three main mechanisms: (1) catalase, superoxide dismutase and glutathione played important roles as the first defence against reactive oxygen species; (2) antioxidant capacity against peroxyl radicals, glutathione S-transferase, metallothionein prevent protein damage and (3) metals/metalloids sequestration into oyster shells as a mechanism of oyster detoxification. However, the estimated daily intake, target hazard quotient, and hazard index showed that the human consumption of oysters would not represent a human health risk. Among 14 analysed metals/metalloids, chemometrics indicate that Mn, As, Pb, Zn and Fe overload the antioxidant system leading to morphological alterations in gills. Overall, results indicated cellular vacuolization and increases in mucous cell density as defence mechanisms to prevent metals/metalloids accumulation and the reduction in gill cilia; these have long-term implications in respiration and feeding and, consequently, for growth and development. The integration of data from different sites and environmental conditions using chemometrics highlights the main biological patterns of detoxification from a neotropical estuarine bivalve, indicating the way in which species can cope with metals/metalloids contamination and its ecological consequences.