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PubMed2004

Occurrence of Vibrio vulnificus in fish and shellfish available from markets in China.

Vibrio vulnificus is a naturally occurring estuarine bacterium often associated with disease such as septicemia in humans following consumption of raw and lightly cooked seafood. In China and neighboring countries, rapid economic growth has encouraged increased consumption of seafood, and dietary habits are changing, with more people eating raw fish. In this study, the prevalence of V. vulnificus was investigated in 48 samples from 11 species of live seafood available from markets in coastal cities of China. The bacterium was detected in four of four razor clam samples, in seven of seven giant tiger prawn samples, and in five of nine mantis shrimp samples. The bacterium was also found in water samples of the prawn aquaria at the markets. The maximum level of V. vulnificus was 3.4 log CFU/g in the razor clam samples and 4.9 log CFU/g in the prawn samples by a direct spreading method. Differential bacterial counts on the prawn body revealed that most of the bacteria were found on the shells (exoskeletons), with very few in the edible muscle. However, dense populations can be found in the intestines. Biochemical tests indicated that the isolates of V. vulnificus were biotype 1 strain, which is pathogenic to humans. These isolates were susceptible to ampicillin, penicillin, kanamycin, streptomycin, and erythromycin. These results suggest that V. vulnificus is a potential health hazard to humans in cities consuming and handling live shellfish, especially giant tiger prawns.

Animals↗

PubMed2005

Development of a quantitative real-time PCR method for estimation of the total number of Vibrio parahaemolyticus in contaminated shellfish and seawater.

A real-time PCR method targeting the toxR gene of Vibrio parahaemolyticus was developed to quantify the number of V. parahaemolyticus cells, including those of both the hemolysin-producing and nonproducing strains. The specificity of the primer and probe set was confirmed using 25 strains of V. parahaemolyticus and 30 strains of other microbial species. We determined the threshold cycle number using the real-time PCR and the number of V. parahaemolyticus cells by plate count using serially diluted pure culture and developed a standard curve for quantification. Standard curves for V. parahaemolyticus in seawater and seafood were established using artificially inoculated samples. The threshold cycle number and the number of V. parahaemolyticus cells were correlated with 10(1) to 10(7) CFU/ml in pure culture, seawater, and shellfish homogenate. The real-time PCR method developed in this study was compared with the most-probable-number method in seafood samples that were naturally contaminated. The differences in the number of V. parahaemolyticus cells as determined by the culture method and the PCR method were less than 10-fold.

Animals↗

PubMed2001

Paralytic shellfish poisoning: a potential public health problem.

Paralytic shellfish poisoning (PSP) is a serious illness in which neurological symptoms predominate. Recovery is usually complete and uncomplicated, but in severe cases there may be respiratory paralysis and death. Most cases follow consumption of bivalve molluscs that have filter-fed on toxic marine microalgae (phytoplankton). Microalgae capable of causing the intoxication have been recorded in all States of Australia, and major toxic blooms have occurred in Tasmania, Victoria and South Australia.

Adult↗

PubMed1976

A simplified method for the gas-liquid chromatographic determination of methyl mercury in fish and shellfish.

A simple acetone wash of the fish sample which removes lipids and other organic materials replaces the cystein cleanup specified in other methods. Methyl mercury is freed by hydrochloric acid, extracted into benzene, and determined with a gas-liquid chromatograph equipped with an electron capture detector. The method is quantitative for methyl mercury levels as low as 0.10 ppm in fish and shellfish. Ethyl mercury chloride may be used as an internal standard to detect unsuspected error or instrumental parameter variation.

Animals↗

PubMed2000

[Neurological features after consumption of a variety of neo-caledonian shellfish].

A few days after a seafood meal a patient suffered ataxia and stupor. His examination revealed a confused patient with cerebellar signs and ocular disturbances (hypotropia). Blood results, cerebrospinal fluid and brain CT scan were unremarkable. The patient developed a septic shock and died 4 weeks after admission. No necropsy was performed. Questioning his family confirmed that he had eaten a shellfish meal a few hours before onset of the digestive signs. Trocas (Tectus pyramis) were definitely identified. The clinical picture strongly suggested a seafood poisoning, namely ciguatera. However, no toxicologic assay was performed. To our knowledge, this poisoning has never been reported with trocas. Nevertheless, the feeding habits of trocas would suggest similarity with ciguatera poisoning.

Adult↗

PubMed2001

General outbreaks of infectious intestinal disease associated with fish and shellfish, England and Wales, 1992-1999.

Between 1992 and 1999 1425 foodborne general outbreaks of Infectious Intestinal Disease (IID) were reported to the PHLS Communicable Disease Surveillance Centre. Of these, 148 (10%) were associated with the consumption of fish and shellfish. Three main aetiologies were identified. Outbreaks associated with fish (47%) occurred more frequently in the summer months, and were linked with Scombrotoxic fish poisoning caused by the consumption of tuna that was improperly stored. Outbreaks associated with molluscs (36%) were associated with the consumption of oysters contaminated with viral pathogens, particularly in February. Outbreaks associated with the consumption of crustaceans (11%) often involved eating prawns that contained either salmonellas or viral pathogens. The maintenance of microbial quality from prior to capture/harvesting until the moment of consumption, based on a Hazard Analysis and Critical Control Point style approach, is essential if gastrointestinal illness associated with such produce is to be avoided.

Adolescent↗

PubMedDate not supplied

Development of reference materials for paralytic shellfish poisoning toxins.

A project was undertaken to develop mussel reference materials that were certified for their mass fractions of saxitoxin and decarbamoyl-saxitoxin. Fifteen laboratories from various European countries participated. Three of these had major responsibility for substantial parts of the work and overall coordination of the project. The project involved 4 main activities: (1) procurement and characterization of calibrants; (2) improvement of analytical methodology; (3) preparation of reference materials, including homogeneity and stability studies; (4) 2 interlaboratory studies and a certification exercise. The joint activities resulted in 3 homogeneous and stable reference materials: 2 lyophilized mussel materials with and without naturally incurred paralytic shellfish poisoning (PSP) toxins, and a saxitoxin enrichment solution. The reference materials were certified with respect to their saxitoxin and decarbamoyl-saxitoxin content. The lyophilized mussel material with PSP toxins (CRM 542) contained <0.07 mg saxitoxin x 2HCl/kg and 1.59 +/- 0.20 mg decarbamoyl-saxitoxin x 2HCl/kg. The lyophilized mussel material without PSP toxins (CRM 543) contained <0.07 mg saxitoxin x 2HCl/kg and <0.04 mg decarbamoyl-saxitoxin x 2HCl/kg. The certified value of the saxitoxin mass fraction in the saxitoxin enrichment solution (CRM 663) was 9.8 +/- 1.2 microg/g.

Animals↗

PubMed2001

[High performance liquid chromatographic determination of domoic acid in shellfish samples].

Domoic acid in shellfish samples was determined by HPLC with DAD/UV detector at 242 nm. Samples were extracted with methanol-water followed by clean-up of the extracts with strong anion exchange solid phase extraction cartridge(3 mL LC-SAX). Zorbax SB-C18 column, 150 mm x 4.6 mm i.d., and mobile phase of acetonitrile-0.1% aqueous trifluoroacetic acid(13:87, V/V) were used for the assay. The quantitative analysis was performed with external standard. The calibration curve of domoic acid was linear in the range of 1.0 m/L-25.0 mg/L and the detection limit was ca. 0.2 microgram/g.

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PubMed2003

Environmental factors influencing the microbiological contamination of commercially harvested shellfish.

Filter-feeding bivalve molluscs (such as oysters, clams, mussels and cockles) can concentrate contaminants from the water column. The extent of faecal contamination in shellfish is usually estimated by determining the concentration of faecal coliforms and/or Escherichia coli. Three sample points in each of three geographically separate commercial shellfisheries were selected for analysis for the effect of season, spring/neap and high/low tidal cycles, rainfall and wind direction on the results of routine E. coli monitoring. General linear modelling was used for the analyses. The principle factors affecting the contamination of shellfisheries were season, high/low tidal cycle and rainfall. The effects varied between harvesting areas and between individual sampling points within harvesting areas. Undertaking such analyses for all harvesting areas would contribute to the management of monitoring programmes and assist in the evaluation of potentially contaminating sources, such as sewage discharges. The type of analyses undertaken on E. coli monitoring data would also be pertinent for the analysis of putative viral indicators, such as F+ coliphage, and could be extended to data on bacterial and viral pathogens.

Animals↗

PubMed2003

[Neurological manifestations of fish, mollusk and shellfish poisoning].

Sea-food poisoning is observed in several areas of the world. Intoxication results from ingestion of fresh fish, mollusks, or shellfish contaminated by toxins produced by microorganisms (dinoflagellates). Neurological manifestations are sometimes associated with signs and may be life-threatening. We describe here the principle toxins, their geographic distribution, clinical manifestations, therapeutic management, and possible prevention measures.

Adult↗

PubMedDate not supplied

A study of ten toxins associated with paralytic shellfish poison using prechromatographic oxidation and liquid chromatography with fluorescence detection.

Ten paralytic shellfish toxins [saxitoxin, neosaxitoxin, B-1, B-2, gonyautoxin 1, 2, and 3 (i.e., GTX-1, GTX-2, and GTX-3), C-1, C-2, and C-3] were oxidized at room temperature under mildly basic conditions with hydrogen peroxide or periodic acid. The products were then analyzed by liquid chromatography (LC). The N-1-hydroxylated toxins (neosaxitoxin, B-2, GTX-1, and C-3) formed fluorescent products after periodate oxidation at ca pH 8.7, but did not form fluorescent derivatives with peroxide oxidation. The non-N-1-hydroxylated toxins (saxitoxin, B-1, GTX-2, GTX-3, C-1, and C-2) formed highly fluorescent derivatives with both peroxide and periodate oxidations. Individual toxins produced mainly single fluorescent peaks by reverse-phase LC. However, all GTX toxins eluted with the same retention time. Also, C-1 and C-2 eluted together, as did neosaxitoxin and B-2. The non-N-1-hydroxylated toxins could be detected in quantities as low as 20-50 pg/injection, while the N-1-hydroxy analogues could be detected at levels as low as 100-500 pg/injection. UV absorption and fluorescence emission spectra were similar for the oxidation products of all toxins examined (max. 333 +/- 2 nm absorption, 389 +/- 4 nm fluorescence emission).

Animals↗

PubMed1991

Occurrence of faecal bacteria, Salmonella and antigens associated with hepatitis A virus in shellfish.

An investigation was carried out over a one year period to examine jointly the occurrence of faecal bacteria, salmonella and the presence of antigens associated with the hepatitis A virus (HAV) in oysters (Crassostrea gigas), mussels (Mytilus edulis, Mytilus galloprovincialis) and cockles (Cerastoderma edule), taken from 8 shellfish farming areas or natural beds along the French coast. For the faecal coliforms (FC) and faecal streptococci (FS), statistical analysis of the 176 samples examined shows a statistically significant difference between sampling stations (F = 44.39 and F = 26.69 respectively, p less than 0.001): 4 of the 8 stations are more highly contaminated. Salmonella and antigens associated with HAV were detected in 5% and 1.7% respectively of the samples analysed. Frequency of isolation of salmonella is higher for the group of sampling stations where the mean levels of contamination by FC and FS are highest. The presence of HAV associated antigens was detected for the group of stations showing the lowest mean contamination levels. Taking all sample stations together, the percentage of isolation of salmonella differs significantly (chi 2 = 7.28, p less than 0.01) for the two classes of FC established on the basis of the threshold value (300 FC). There is no difference between the two classes of FS. For the HAV-associated antigens, detection percentages are similar for the two classes of results for FC and FS. Within each sampling station, considered independently, no particular correlation was found between the various viral and bacterial markers investigated.

Animals↗

PubMed2006

Total and inorganic arsenic in Mid-Atlantic marine fish and shellfish and implications for fish advisories.

Sampling was conducted in 2002 to determine the total concentration and chemical speciation of arsenic in several marine fish and shellfish species collected from the Delaware Inland Bays and the Delaware Estuary, both of which are important estuarine waterbodies in the US Mid-Atlantic region that support recreational and commercial fishing. Edible meats from summer flounder (Paralicthys dentatus), striped bass (Marone saxatilis), Atlantic croaker (Micropogonias undulates), and hard clam (Mercenaria mercenaria) were tested. Total arsenic was highest in summer flounder, followed by hard clam, then striped bass, and finally, Atlantic croaker. Total arsenic was higher in summer flounder collected during the spring, as these fish migrated into the Inland Bays from the continental shelf, compared with levels in summer flounder collected during the fall, after these fish had spent the summer in the Inland Bays. Similarly, striped bass collected in the early spring close to the ocean had higher total arsenic levels compared with levels detected in striped bass collected later during the year in waters with lower salinity. Speciation of arsenic revealed low concentrations (0.00048-0.02 microg/g wet wt) of toxic inorganic arsenic. Dimethylarsinic acid was more than an order of magnitude greater in hard clam meats than in the other species tested, a finding that was attributed to arsenic uptake by phytoplankton and subsequent dietary uptake by the clam. Risk assessment using the inorganic arsenic concentrations was used to conclude that a fish consumption advisory is not warranted.

Animals↗

PubMed1991

[11 cases of anaphylaxis caused by grand keyhole limpet (abalone like shellfish)].

We reported 11 cases of patients who developed moderate to severe anaphylactic reactions induced by the ingestion of grand keyhole limpet (GKL) and abalone. Specific IgE-mediated hypersensitivity to these shellfish was demonstrated by history, skin prick test, RAST and immunoblotting. The RAST inhibition technique revealed cross antigenicity between GKL, abalone and keyhole limpet hemocyanin. By immunoblotting analysis, the major antigens of GKL are shown in the MW range of about 38 Kd and 80 Kd.

Adolescent↗

PubMedDate not supplied

Comparison of microwave digestion with conventional wet ashing and dry ashing digestion for analysis of lead, cadmium, chromium, copper, and zinc in shellfish by flame atomic absorption spectroscopy.

A closed vessel microwave digestion procedure was developed for shellfish samples. This procedure was compared with wet and dry ash procedures for levels of lead, cadmium, chromium, copper, and zinc. Results obtained for microwave and conventional wet ash digestion were comparable. The dry ashing procedure produced results consistently lower than either of the other methods. Recoveries ranged from 80-92% for microwave and wet ashing procedures and 54-72% for the dry ashing procedure. Accuracy was also determined by analyzing lobster hepatopancreas marine reference material. Values for Pb, Cd, and Cr fell within the range specified for the reference material for all 3 digestion procedures; however, values were lower for Cu and Zn. Results of this study show that microwave digestion is comparable to wet ashing.

Animals↗

PubMedDate not supplied

Identification of Escherichia coli from shellfish and related environments by automicrobic system.

A total of 463 fecal coliform positive isolates obtained from shellfish and related samples gave typical Escherichia coli IMViC reactions. E. coli identifications for 458 (99%) of these isolates were confirmed using a combination of the Automicrobic System (AMS) and the API 20E system (reference system). The AMS (test system) identified 433 isolates as E. coli; the remaining 25 (5%) isolates were identified as E. hermanii by the test system and as E. coli by the reference system. Additional tests performed on the isolates identified as E. hermanii confirmed those AMS identifications to be incorrect.

Animals↗

PubMedDate not supplied

Rapid determination of methyl mercury in fish and shellfish: collaborative study.

A modification of the official AOAC method for determining methyl mercury in fish and shellfish was studied in 8 laboratories. Methyl mercury is isolated from homogenized, acetone-washed tissue by adding HCl and extracting into toluene the methyl mercuric chloride produced. The extract is analyzed for methyl mercuric chloride by electron capture gas chromatography. Collaborators determined methyl mercury in blind duplicate homogenates at 2 levels in tuna and at 1 level in swordfish and oysters. Collaborators also analyzed single homogenates of swordfish and oysters containing methyl mercury at a second level. Both fortified and unfortified tissues were analyzed. Methyl-bound mercury in the commodities ranged from 0.50 to 2.30 micrograms Hg/g. Reproducibility coefficients of variation ranged from 4 to 15%. Accuracy, measured by comparison to reference values, ranged from 92 to 101%. Recovery from fortified homogenates ranged from 86 to 98%. Reference values and unfortified levels were determined in the author's laboratory by replicate analysis of fortified and unfortified commodities. The method has been approved interim official first action.

Animals↗

PubMedDate not supplied

Rapid, semimicro method for determination of polycyclic aromatic hydrocarbons in shellfish by automated gel permeation/liquid chromatography.

A simple, rapid, easily automated method is described for the determination of polycyclic aromatic hydrocarbons (PAHs) in shellfish such as American lobster (Homarus americanus) and blue mussel (Mytilus edulis). PAHs are extracted from small amounts (1-8 g) of tissue by saponification in 1N ethanolic potassium hydroxide followed by partitioning into 2,2,4-trimethylpentane. This solution is evaporated just to dryness by rotary evaporation and the residue is dissolved in cyclohexane-dichloromethane (1 + 1) for gel permeation chromatography (GPC) on Bio-Beads SX-3. The GPC procedure is ideal as a screening method in the range 25-18 000 ng PAHs/g tissue. If individual PAH measurements are required, the appropriate GPC fraction is collected and PAHs are separated by reverse phase liquid chromatography (LC) with fluorometric detection. Individual PAHs at concentrations as low as 0.25-10 ng/g can be determined. Recoveries of added fluoranthene, pyrene, benz[a]anthracene, chrysene, benzo[e]pyrene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenz[a,h]anthracene, benzo[ghi]perylene, and indeno[1,2,3-cd]pyrene were quantitative, with relative standard deviations ranging from 0.0 to 16.9%.

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