Cockle Samples Research Articles

Rapid on-site authentication of three cockle species using real-time loop-mediated isothermal amplification (LAMP) assay

Cockles, crucial for commercial fishing and aquaculture, emerge as highly marketable shellfish. However, the morphological similarities among various cockle species are frequently exploited for shellfish fraud. In this study, we developed LAMP assays (end-point LAMP and real-time LAMP) to detect three commercially important cockle species: Tegillarca granosa, Anadara broughtonii, and Anadara kagoshimensis. The primers were designed based on mitochondrial DNA and used to develop LAMP assays. Exclusivity was assessed using 17 shellfish species, and no cross-reactivity was confirmed. The estimate of the detection limit was determined to be 0.0001 ng. The established assays were further refined to create an on-site real-time LAMP assay by combining fast DNA isolation with a real-time fluorometer for field application. The effectiveness of the on-site real-time LAMP assay was successfully verified using 38 commercial samples, with analysis accuracy confirmed using a DNA extraction kit. Consequently, the on-site real-time LAMP assay can complete the whole procedure, including DNA extraction, real-time LAMP reaction, and data analysis within a 45 min timeframe, maintaining the accuracy of detecting three cockle species from processed cockle samples in the field. Our method proves valuable for detecting shellfish fraud by identifying cockle species using samples of both raw and processed products in the field.

Investigation of microplastic contamination in blood cockles and green mussels from selected aquaculture farms and markets in Thailand.

Recent studies have indicated that bivalves are bioindicators for microplastic pollution since they are filter feeders and accumulate microplastics (MPs) during their feeding process. This study focused on the investigation of MPs in blood cockles (Tegillarca granosa) and green mussels (Perna viridis) from selected aquaculture farms and markets in Thailand. The abundance of MPs was identified by fluorescence microscopy with Nile Red tagging and the polymer detection by micro-Fourier Transform Infrared Spectroscopy (micro-FTIR). The number of MPs in blood cockle samples from the Khlong Dan market and the BangBo aquaculture farm was 11±5 and 6±1 particles/individual, respectively. For green mussel samples, the number of MPs from the Talaad Thai market and the Sriracha fisheries research station was 96±19 and 11±7 particles/individual, respectively. The results of the study indicate that the number of MPs in bivalve samples from the markets is much higher than in the aquaculture farms. This probably is due to the contamination of MPs in bivalves during the packaging and transportation processes. However, further studies are needed to confirm this. The predominant MPs were fragments and fibres with a size range of 0.05-0.3mm. Most polymers were polypropylene, polyethylene, copolymer, polyester, and nylon. In brief, this study showed the contamination of MPs in bivalves cultivated for human consumption. The accumulation of MPs in these marine bivalves can lead to the biomagnification of MPs along the food chain. This can impact food safety and human health.

Lead and Copper Concentration in Sediment and Blood Cockle (Anadara granosa) in the Coastal Waters of Panipahan, Rokan Hilir, Riau Province

This research was conducted in March 2020 with the aim of evaluating the heavy metal content of Pb and Cu in sediment and blood cockle (Anadara granosa). The sediment and blood cockle samples were taken from Panipahan coastal waters, Panipahan Village and Teluk Pulai Village, Rokan Hilir Regency, Riau Province. The results of this study showed that the highest content of Pb and Cu in sediments was found in the surrounding area of residential areas (47.4570 µg / g and 104.1320 µg / g), while in blood cockle, the highest content was found around areas far from anthropogenic activity. The Pb content in the sediments did not show a significant effect on the Pb content in blood cockles, as well as the Cu. The results of the calculation of the MPI (Metal Pollution Index) value showed that Panipahan coastal waters are still classified as low pollution level.

Microplastic abundance in blood cockle Anadara granosa (linnaeus, 1758) at Lada Bay, Pandeglang, Banten

Microplastic in the marine ecosystem has become a growing global concern over the past decades. This research analyzed the abundance and type of microplastic in the blood cockle anadara granosa, water, and sediment from Lada Bay, Pandeglang, Banten, Indonesia. The sampling of the blood cockle, water and sediment were collected from 3 different stations. Digestive tracts and respiratory organs from blood cockle were destructed with HNO3 65 %, water and sediment samples were mixed into the concentrated NaCl solution. The results showed a microplastic abundance of 248.5 ± 3.81 particle/L in water, 169.200 ± 5.184 particle/kg in sediment and 618.8 ± 121.4 particles/individuals in the cockle. Besides, in blood cockle from the traditional markets, it was found 566.7 ± 133.1 particle/individuals microplastic. Fiber is the type of microplastic that was most commonly found in the samples of cockles (58.06 %), waters (61.23 %) and sediments (57.82 %). The river was indicated as a microplastic source to the sea. The station 3 in ± 60 m near the river mouth has a higher microplastic concentration with an average of 86.17 ± 2.36 particle/l.62666.67 ± 1803.7 particle/Kg and 720 ± 131.1 particle/individual, compared to station 1 and 2 which is further away from the river.

Booster Biocides Levels in the Major Blood Cockle (Tegillarca granosa L., 1758) Cultivation Areas along the Coastal Area of Peninsular Malaysia

Booster biocides have been rapidly growing in use, mainly in the shipping industry and in agricultural activities. The use of booster biocides is known to cause adverse effects on marine ecosystems, such as by inhibiting the photosynthesis process in marine plants, and they have the potential to accumulate in marine organisms. In the present study, booster biocides of Irgarol 1051, diuron, 3,4-dichloroaniline (3,4-DCA) and chlorothalonil were measured in the major blood cockle (Tegillarca granosa) cultivation areas along the west coast of Peninsular Malaysia. The highest Irgarol 1051 mean was found in the blood cockle with a value of 98.92 ± 13.65 µg/kg in Kapar, Selangor, while the means of diuron and its metabolites and 3,4-DCA showed the highest values of 40.31 ± 7.61 and 41.42 ± 21.58 µg/kg in Kapar, Selangor and Sungai Ayam, Johor, respectively. Sungai Ayam, Johor also exhibited the highest amount of chlorothalonil of 29.76 ± 8.80 µg/kg. By referring to sediment quality guidelines, about 72% and more than 90% of sediment samples exceeded the environmental risk limits (ERLs) and maximum permissible concentration (MPC) for Irgarol 1051 and diuron, respectively. However, referring to the risk characterization ratio (RCR), none of the blood cockle samples exceeded 1, which means that there is no potential for adverse effects to occur. Thus, the contaminants in the marine ecosystem caused by booster biocides are highlighted as a serious issue, mainly in sediment.

Microplastic contamination on Anadara granosa Linnaeus 1758 in Pangkal Babu mangrove forest area, Tanjung Jabung Barat district, Jambi

Anadara granosa is an important food source for people in Tanjung Jabung Barat District, Jambi. This study uses samples of cockle, sediment and water. The results showed a 100% sample containing microplastic. The types of microplastic found are fiber, fragments and films. The average microplastic amount in A. granosa individuals was 434 ± 97.05 particles/individuals. Fiber is the type of microplastic that is most commonly found in samples of cockles, sediments and water. In the blood cockles sample, fiber was found as much as 180.6 ± 21.22 particles/individual and 4.1 ± 0.43 particles/g cockle. Fiber is also found with high concentration in water samples of 128.3 ± 0.15 particles/L. The river is indicated as a microplastic source to the sea. The station sample 1 in 100 m near the river mouth has a higher microplastic concentration with an average of 448.3 ± 53.92 microplastic/individual, compared to station sample 3 which is only 420.3 ± 42.66 microplastic/individual.

Legacy and emerging pollutants in marine bivalves from the Galician coast (NW Spain)

The presence of pollutants in estuary and oceanic systems is a global problem and a serious concern to human and environmental health. Usually, environmental monitoring studies consider classical persistent organic pollutants (POPs). However, the lists of POPs keep continuously growing and new POPs and other emerging pollutants should be considered in new monitoring programs. So, this study aimed to investigate the distribution and profile of classical POPs (polychlorinated biphenyl (PCBs), organochlorine pesticides (OCPs), and polycyclic aromatic hydrocarbons (PAHs)), new POPs and emerging pollutants (polybrominated diphenyl ethers (PBDEs), perfluorinated compounds (PFCs), novel halogenated flame retardants (NFRs) and UV filters) in bivalve mollusc samples (both raft-cultivated and wild mussel, Mytilus galloprovincialis; cockle, Cerestoderma edule; and clam, Ruditapes descussatus) collected in nine Galician Rias during the period February 2012 to February 2013. A predominance of PAHs (6.8–317 ng/g dry weight (dw)) followed by PCBs (0.47–261 ng/g dw), UV filters (1.4–157 ng/g dw), PFCs (0.53–62 ng/g dw), OCPs (0.07–29 ng/g dw), PBDEs (0.31–6.6 ng/g dw) and NFRs (0.07–3.2 ng/g dw) was found in the studied bivalves, being the UV filter octocrylene the compound found at the highest concentration (141 ng/g dw in a cockle sample), while the PAHs chrysene and benzo(b)fluoranthene were the compounds with the highest average concentration (20 and 14 ng/g dw, respectively). Inter-species, temporal and geographical variations on pollutants concentration were assessed by multifactorial analysis of variance. Statistically significant differences among the type of mollusc were observed for levels of organochlorinated and organobrominated pollutants considered (PCBs, OCPs and PBDEs), which were detected at higher concentrations in wild mussel. On the other hand, the main PFCs and UV filters showed a higher detection frequency in cockle samples. Location played significant role for PAHs, PCBs and the main PBDEs, being the most polluted rias those more industrialized and populated, i.e. A Coruña, Ferrol and/or Vigo. Finally, sampling timepoint was also a significant factor for most of the families considered but with different profiles. Thus, PAHs and PCBs showed higher concentrations in both February 2012 and 2013 and lower in August 2012, while the main PBDEs were measured at higher concentrations in November 2012 and lower in February 2012; and the main NFRs, PFCs and UV filters were present at lower levels in February 2013.

Occurrence of methicillin-resistant Staphylococcus aureus in raw shellfish at retail markets in Malaysia and antibacterial efficacies of black seed (Nigella sativa) oil against MRSA

Methicillin-resistant Staphylococcus aureus (MRSA) is a remarkable pathogen which causes nosocomial diseases worldwide. In this study, raw green mussel and cockle samples in Malaysia were collected and investigated for the occurrence of MRSA. A total of 80 samples were analyzed using phenotypic and molecular approaches. A assembling of the most probable number (MPN) with multiplex polymerase chain reaction (mPCR) technique was used to identify MRSA in the samples. The occurrences of S. aureus and MRSA in shellfish samples were 15% and 8.75%, respectively, with the microbial load from <3 to 12.2 MPN/g. MRSA isolates were tested for their sensitivity to 17 generally used antibiotic agents by using disc diffusion assay. All the isolates were resistant to amikacin and penicillin. However, sensitivity was recorded for cefoxitin, ceftaroline, chloramphenicol, ciprofloxacin, clarithromycin levofloxacin, linezolid, ofloxacin, quinupristin/dalfopristin, tetracycline and trimethoprim-sulfamethoxazole. Moreover, the antimicrobial activities against MRSA were evaluated using minimum inhibited concentration (MIC) and minimum bactericidal concentration (MBC). The findings revealed that the black seed oil acted as a potent inhibitor of MRSA. The lowest value of MIC and MBC of black seed oil against MRSA was 32.8 and 42.2 mg/mL, respectively. The detection of MRSA in this study deserves a public attention because shellfish are commonly eaten raw or partially cooked in Malaysia.

Evaluating health risks posed by heavy metals to humans consuming blood cockles (Anadara granosa) from the Upper Gulf of Thailand.

There is global concern about heavy metal contamination in the environment. Adverse health effects can be caused by heavy metals in contaminated food and water. Therefore, environmental monitoring studies and risk assessments should be conducted periodically. In this study, we measured levels of Cd, Cr, Cu, Hg, Mn, Ni, Pb, and Zn in blood cockles (Anadara granosa) collected from three locations in the Upper Gulf of Thailand. Hazard quotients and hazard indices were calculated to evaluate the health risks posed by heavy metals in consumed blood cockles. Heavy metal concentrations in all of the blood cockle samples were lower than the relevant food standards. The hazard quotients and hazard indices were <1 in all three sampling areas, indicating that adverse health effects were not likely to be caused by exposure to heavy metals in blood cockles over a human lifetime.

FOOD SAFETY ASPECTS IN BLOOD COCKLES (Tegillarca granosa) CULTURED OFF SELANGOR, PENINSULAR MALAYSIA

This study evaluates some food safety aspects of the blood cockle (Tegillarca granosa) and its culture waters at Bagan Nakhoda Omar (BNO), Sungai Besar (SB) and Bagan Sungai Buloh (BSB) in Selangor. Samplings of cockles and seawater from the culture beds were carried out from Oct 2014 to Mar 2015 to analyse for fecal indicator bacteria, hepatitis A virus and saxitoxin in cockles and harmful phytoplankton and heavy metals in seawater. The results indicated that cockles from BNO, SB and BSB were of Class C category suggesting that the cockles could only be sold for human consumption after re-laying, followed by purification or heat treatment processes. Meanwhile, the cockle culture areas of BNO, SB and BSB were classified as ‘conditionally approved’. The saxitoxin levels in cockle samples from BNO, SB and BSB were 0.12-0.80, 0.05-0.25 and 0.05-0.18 nmol/g, respectively and hepatitis A virus was not detected in the cockels samples. Phytoplankton composition was dominated by the diatom group (>96%). Pseudo-nitzhia spp. and Dinophysis caudata were commonly found but at low cell counts. The levels of Cr, Zn, Cu, As and Hg were higher than the Malaysian standards while Se, Cd and Pb were within the safe limits. Further investigation should be carried out to identify the pattern and source of pollution throughout a year so that appropriate and cost-effective corrective actions could be taken to prevent future pollution and adverse effect to the public. Keywords: food safety, phytoplankton, cockles, culture waters, Selangor

Matrix solid-phase dispersion combined to liquid chromatography–tandem mass spectrometry for the determination of paraben preservatives in mollusks

A method for the extraction and determination of seven parabens, esters of 4-hydroxybenzoic acid, widely used as preservatives in personal care products, pharmaceuticals, etc., and two chlorinated derivatives (mono- and di-chloro methyl paraben) from mollusk samples was developed by combining matrix solid-phase dispersion (MSPD) and liquid chromatography–tandem mass spectrometry. MSPD parameters, such as solvent, solid support and clean-up sorbent, were optimized. Besides, since blank problems were observed for some parabens, these were investigated and blanks were tackled by precleaning all sorbents prior to use. Under final conditions, 0.5g of freeze-dried mollusk were dispersed with 1.2g of silica and packed into a cartridge containing 3g of C18, as on-line clean-up sorbent. This cartridge was eluted with 10mL of acetonitrile, evaporated and reconstituted in methanol for analysis. In the validation stage, successful linearity (R2>0.999), recoveries (between 71 and 117% for most analytes), precision (RSD lower than 21%) and limits of detection and quantification (LOD and LOQ, lower than 0.4 and 1.4ngg−1 dry weight respectively) levels were achieved. Finally, the new methodology was applied to mussel, clam and cockle samples. Methyl paraben was above the LOQ in five of the six samples (not found in one clam sample) at concentrations up to 7ngg−1 dry weight. Ethyl paraben was found above the LOQ in mussel and cockle samples at a concentration level around 0.3ngg−1. n-Propyl paraben was only above the LOQ in one mussel sample.

Serogroup, virulence, and molecular traits of Vibrio parahaemolyticus isolated from clinical and cockle sources in northeastern Thailand

Vibrio parahaemolyticus is responsible for seafood-borne gastroenteritis worldwide. Isolates of V. parahaemolyticus from clinical samples (n=74) and cockles (Anadara granosa) (n=74) in Thailand were analyzed by serotyping, determination of virulence and related marker genes present, response to antimicrobial agents, and genetic relatedness. Serological analysis revealed 31 different serotypes, 10 of which occurred among both clinical and cockle samples. The clinical isolates commonly included the pandemic serogroup O3:K6, while a few of the cockle isolates exhibited likely pandemic serovariants such as O3:KUT and O4:KUT, but not O3:K6. The pandemic (orf8 gene-positive) strains were more frequently found among clinical isolates (78.4%) than cockle isolates (28.4%) (p<0.001). Likewise, the virulence and related marker genes were more commonly detected among clinical than cockle isolates; i.e., tdh gene (93.2% versus 29.7%), vcrD2 (97.3% versus 23.0%), vopB2 (89.2% versus 13.5%), vopT (98.6% versus 36.5%) (all p<0.001) and trh (10.8% versus 1.4%) (p<0.05). Pulsed-field gel electrophoresis of NotI-digested genomic DNA of 41 randomly selected V. parahaemolyticus isolates representing different serotypes produced 33 pulsotypes that formed 5 different clusters (clonal complexes) (A-E) in a dendrogram. Vibrio parahaemolyticus O3:K6 and likely related pandemic serotypes were especially common among the numerous clinical isolates in cluster C, suggesting a close clonal link among many of these isolates. Most clinical and cockle isolates were resistant to ampicillin. This study indicates that O3:K6 and its likely serovariants based on the PFGE clusters, are causative agents. Seafoods such as cockles potentially serve as a source of virulent V. parahaemolyticus, but further work is required to identify possible additional sources.

Concentration of Mercury in Cockles (Anadara granosa and A. antiquata) Harvested from Estuaries of Western Lombok, Indonesia, and Potential Risks to Human Health.

This study measured the levels of total mercury (tHg) in the whole tissues of cockles (Anadara granosa and A. antiquata) harvested from three estuaries of Western Lombok Island (WLI), Indonesia. This paper also evaluated the hazard level posed by the mercury in relation to the maximum residual limit for human consumption and to estimate the weekly intake and compare it with the provisional tolerable weekly intake (PTWI). The tHg concentrations in A. granosa ranged from 0.020 to 0.070 mg kg(-1), and those in A. antiquata were between 0.032 and 0.077 mg kg(-1) at all locations. All samples of cockles harvested from WLI contain tHg below the permissible limit for human consumption. The maximum weekly intakes for total mercury by coastal people range from 0.28 to 1.08 µg kg(-1) b.w., and they are below the recommended values of PTWI (5.6 µg kg(-1) b.w.). If it is assumed that 100% of the Hg in cockles is methyl mercury (MeHg), consumption of the indicated amounts at the measured values wouldn't exceed the MeHg PTWI (1.6 µg kg(-1) b.w.).

Mass mortality event of the blood cockle, Anadara granosa, in aquaculture ground along Selangor coast, Peninsular Malaysia

A mass mortality event of blood cockles, Anadara granosa, occurred in aquaculture ground in Selangor in mid-February 2012. To identify factors contributing to this event, we estimated the changes in survival rate and population density of the blood cockles using data from field surveys carried out in late-January and mid-March, 2012. In addition, blood cockle samples were used for histological observation of various tissues with a light microscope. Furthermore, we examined the environmental factors that seemed to be involved in this mass mortality event using environmental data obtained in two surveys and weather data for the Selangor region from late-January to mid-March 2012. As a result of the field surveys and the histological observation, the mortality was estimated to be 30 % over, and the blood cockles were shown to be in the spawning season at this time of year. In addition, numerous individuals collected in mid-March had no food in the digestive duct, which suggested low food availability. Precipitation data for the Selangor region showed rainfall of 30 mm/day over four days in mid-February, which suggested an impact of freshwater flooding from rivers on the aquaculture ground. Normally, the blood cockles are tolerant to low-salinity environments. However, the fact that the flooding and associated environmental changes occurred, when the population was debilitated by reproductive activity, may have led to the mass mortality event in association with low food availability.

Vibrio parahaemolyticus and Its Specific Bacteriophages as an Indicator in Cockles (Anadara granosa) for the Risk of V. parahaemolyticus Infection in Southern Thailand

Correlation between the numbers of Vibrio parahaemolyticus and its specific bacteriophages in cockles was investigated from June 2009 to May 2010 in Hat Yai, Songkhla, Thailand. Cockles obtained monthly from a local market were sampled to determine the numbers of V. parahaemolyticus and bacteriophages that could form plaques on ten strains of pandemic and nonpandemic V. parahaemolyticus. In addition, V. parahaemolyticus isolates from clinical samples from Hat Yai hospital over the same period were investigated. All 139 cockles sampled were positive for V. parahaemolyticus. However, only 76 of them were positive for bacteriophages. During the testing period, the number of bacteriophages was not significantly correlated with the incidence of V. parahaemolyticus-infected patients, but the numbers of V. parahaemolyticus isolates from the cockle samples were closely related to the number of infected patients. The bacteriophages isolated from V. parahaemolyticus also infected Vibrio alginolyticus and Vibrio mimicus, suggesting that the broad host range of phages may be a factor of providing the possibility of their participation in the processes of genetic exchange between V. parahaemolyticus and closely related Vibrio spp. In conclusion, this study indicated that the number of V. parahaemolyticus in cockles may be a useful tool for predicting the relative risk of infection by V. parahaemolyticus in this area of Thailand.

Occurrence and molecular identification of Vibrio parahaemolyticus in retail shellfish in Mansoura, Egypt

In the present work, we examined 120 shellfish samples (40 each of shrimp, crab and cockle) collected from different fish shops in Mansoura city, Egypt, for the presence of potentially pathogenic strains of Vibrio parahaemolyticus. The conventional method as exemplified by biochemical means indicated that 40 (33.3%) of samples were positive for V. parahaemolyticus. Molecular means as represented by PCR, however, verified that only 20 (16.7%) shellfish samples were positive for V. parahaemolyticus. These 20 positive samples were distributed as 9, 8 and 3 of shrimp, crab and cockle, respectively. Biochemical analyses of the recovered 143 presumptive V. parahaemolyticus colonies indicated that 89 isolates were identified as V. parahaemolyticus. PCR analysis, for the presence of the species-specific toxR gene, indicated that only 27 (30.34%) out of these 89 isolates were verified as V. parahaemolyticus. These molecularly verified 27 strains were distributed as 14, 10 and 3 isolates from the examined shrimp, crab and cockle samples, respectively. Out of the 27 molecularly identified isolates, three (11%) strains were verified to be potentially pathogenic based on detection of tdh and/or trh virulent genes. One of these 3 strains that derived from shrimp was positive for both tdh and trh. The second strain (derived from cockle) was positive for tdh only, while the third one (derived from shrimp) was positive for trh only. The two strains that were positive for tdh, were also verified to be positive for Kanagawa reaction. This study concluded that the examined shellfish may carry the potential human health risk associated with the presence of pathogenic V. parahaemolyticus and that the reliable molecular detection methods should be included in the routine seafood examination in addition to the conventional bacteriological methods.

Influence of disseminated neoplasia, trematode infections and gametogenesis on surfacing and mortality in the cockle Cerastoderma edule

Cerastoderma edule is a widely distributed bivalve mollusc, commercially exploited throughout Europe and is also an important food source for birds and crustaceans. Recently, mass surfacing and mortalities of cockles have been observed and reported at sites in Ireland and elsewhere, particularly in the summer months. One such site is Flaxfort Strand, Courtmacsherry Bay, County Cork, Ireland, an important feeding area used by many seabirds during the summer months. For the past few years large numbers of surfaced cockles have been observed at the site in a moribund condition. Samples of cockles from this area were collected over the summer months and their health status assessed. Cockles that had surfaced (moribund) and those still buried in the sediment were quantified and screened: sex, gonadal maturity and size class of cockles were also determined. Disseminated neoplasia and trematodes were observed in screened cockles. The most significant finding during the study was that mortalities and surfacing of cockles was related to a greater incidence of disseminated neoplasia. No neoplasia was observed in the smallest and largest size classes. There was a significantly higher prevalence of neoplasia in moribund cockles than in buried cockles, whereas in both groups a similar concentration of trematode metacercariae was observed in the screened tissues. Also, most of the cockles that had surfaced were either in the process of spawning or were spent. Overall a much larger percentage of moribund cockles exhibited both trematode infections plus neoplasia compared with buried cockles. A combination of the presence of neoplasia and trematodes, along with stress related to spawning, may immunocompromise the cockless, causing the animals to surface and become moribund.

Paralytic shellfish poisoning due to ingestion of Gymnodinium catenatum contaminated cockles – Application of the AOAC HPLC Official Method

The potent paralytic shellfish toxins (PSTs) produced by Gymnodinium catenatum have appeared irregularly since the onset in 1986 of a monitoring program aimed at preventing contaminated bivalves from the Portuguese coast to reaching the consumer. In years where high contamination levels were attained, sporadic episodes of human poisonings were also recorded, as in 1994. The reappearance of high contamination led to the appearance of new cases during 2007. This study reports details of toxin ingestion, symptomatology and toxin presence in the fluids of one of these victims, an adult male who ingested several kilograms of cockles.In cockle samples collected the week before and during the week when the intoxication took place, the major PSTs detected by the HPLC method based on AOAC Official Method 2005.06 belonged to the sulfamate (81–68 molar percent) and decarbamoyl groups (19–32 molar percent), comprising GTX5, GTX6, C1,2, C3,4, dcNeo, and dcSTX. In the patient urine sample sulfamate and decarbamoyl derivatives were also found, comprising by GTX5 (28%), GTX6 (25%), dcSTX (24%) and dcNeo (22%), but no C toxins and no dcGTX2,3 were detected. Compared to the cockle samples, there was an increase in the proportion of dcSTX, dcNeo and GTX5 (molar percentage) in the urine sample, but not of GTX6. Overall, compounds which had the presence of an O-sulfate at C11 were absent in urine while being relatively abundant in the bivalve (36.5–47.0 molar percent). In blood plasma PSTs were not detected.

Prevalence and Antimicrobial Susceptibilities of Vibrio, Salmonella, and Aeromonas Isolates from Various Uncooked Seafoods in Thailand

Uncooked seafood samples were collected from open markets and supermarkets in Bangkok, Thailand, and were examined for the presence of Vibrio, Salmonella, and Aeromonas species from January to February 2008. From 120 samples, 272 bacterial isolates were identified through biochemical testing. Of all sea bass, shrimp, oyster, and blood cockle samples (30 of each) that were processed for culture, 114 (95%) samples had at least one detectable isolate of Vibrio, Salmonella, or Aeromonas, leaving only 6 (5%) samples free of them. All oyster sample (100%) had at least one pathogen, followed by sea bass (97%), blood cockles (97%), and shrimp (90%). Overall, 111 (92%) of all samples had detectable Vibrio spp., 32 (27%) had detectable Aeromonas spp., and 25 (21%) had detectable Salmonella enterica. There was no overall difference between positive samples collected from fresh markets versus supermarkets (relative risk, 0.97; 95% CI, 0.89 to 1.05). Resistance to ampicillin among isolated pathogens was relatively high (56%), while resistance to 12 other antibiotics, including azithromycin, ciprofloxacin, and trimethoprim-sulfamethoxazole, was relatively low (0, 0, and 3%, respectively). Study results indicate that uncooked seafood in Bangkok, Thailand, commonly harbors enteric pathogens and that consumption of uncooked seafood should be avoided to reduce foodborne illnesses.

Large-scale ultrasonic cleaning system: Design of a multi-transducer device for boat cleaning (20 kHz)

The present study is part of a global project which consists in the development of an automatic cleaning station for immersed boats (cockle, ninepin, etc.) in a self-service mode, associating an innovative ultrasonic device for cleaning with a specific water treatment. The originality of the process is that cleaning is performed by three transducers operating simultaneously at low frequency and moving along the surface, thanks to programmable logic controllers, and that it includes a suction to collect the dirt removed. Therefore, the time required for boat maintenance is shortened, ensuring high quality cleaning without the need for dry docks and avoiding additional pollution in the harbor areas. One of the key points was the evaluation of washing efficiency, as it is really hard to give a quantitative estimation of the dirt removed. To obtain the first design laws, feasibility tests have been carried out on dirty cockle samples and on real boat hulls with a laboratory ultrasonic device. The influence of a large number of parameters was tested such as transducer-probe distance, displacement speed and transmitted power. The obtained data allowed us to design an optimized cleaning device combining high efficiency and speed.