1,721,043 research outputs found
Metodica di estrazione per il rilevamento del virus dell’Epatite A nei molluschi mediante RT-PCR
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Comparison between thiosulphate-citrate-bile salt sucrose (TCBS) agar and CHROMagar Vibrio
No full textConsidering its widespread distribution in marine environments, its fast replication times and low infectious doses and the rapid spread of its strains in recent years, intensive and continuous monitoring of potentially pathogenic Vibrio parahaemolyticus is strongly recommended in order to assess the human health risk arising from shellfish consumption. The lack of epidemiological data points to the need to develop specific methods for detectingV. parahaemolyticus. In this note, the authors compare two platingmedia currently available for isolating V. parahaemolyticus in shellfish. Both approaches involve pre-enrichment of V. parahaemolyticus. One uses thiosulphate-citrate-bile salt sucrose (TCBS) as the isolation medium, while the other uses a chromogenic medium (CHROMagar Vibrio). Next, biochemical identification of isolates was performed with API 20E, followed by PCR assay aimed at the
toxR gene to confirm the cultural and biochemical identification. Comparison of the two methods highlighted that CHRO-Magar Vibrio is more accurate and specific than TCBS. The analysis of data from 160 shellfish samples showed an accuracy and specificity of just 51% and 71% for TCBS compared with 88% and 95% for CA
Detection of potentially pathogenic Aeromonas isolates from Ready To Eat seafood products by PCR analysis
No full textThis study provides data on the prevalence of potentially pathogenic Aeromonas spp. in ready-to-eat (RTE) seafood products by evaluating the occurrence of Aeromonas spp. and the presence of virulence-associated genes. Aeromonas spp. was detected in 57 ⁄ 81 (70.3%) RTE seafood samples. Specifically, Aeromonas spp. was highlighted in 19 ⁄ 21 (90.5%) sushi, in 18 ⁄ 21 (85.7%) sea salad, 11 ⁄ 12 (91.7%) surimi and 9 ⁄ 12 (75%) peeled shrimp samples. Aeromonas spp. was not observed in marinated anchovies and octopus salad samples. Then, PCRs aimed at the hlyA, aerA, alt and ast genes, encoding, respectively, haemolysin A, aerolysin, aeromonas labile temperature cytotonic enterotoxin and aeromonas stable temperature cytotonic entero- toxin, demonstrated a widespread distribution of these genes among Aeromonas isolates. The results underline the need to implement an adequate control plan performing an intensive and continuous monitoring to guarantee the human health
Detection of Vibrio parahaemolyticus in Shellfish using Polymerase Chain Reaction-Enzyme-Linked ImmunoSorbant Assay (PCR-ELISA)
No full textAims: This study evaluated the application of polymerase chain reaction-enzyme-linked immunosorbent assay (PCR-ELISA) for the detection of Vibrio parahaemolyticus in shellfish. Methods and Results: The PCRs were selected to amplify a species-specific sequence region. In particular, internal tl biotin-labelled oligonucleotide probe was used to capture the DIG-labelled PCR products. Next, the probe PCR product hybrids, immobilized on a streptavidin-coated microtiter plate, were detected with peroxidase-conjugated anti-digoxigenin antibody (anti-DIG-POD) and the colorimetric peroxidase substrate ABTS [2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid)] using an ELISA plate reader. Conclusions: The PCR-ELISA system described is a feasible, sensitive method for the direct and specific detection of V. parahaemolyticus in shellfish samples. Compared with gel-based detection methods, PCR-ELISA in this study increased sensitivity by 100-fold for V. parahaemolyticus. Significance and Impact of the Study: The PCR-ELISA described may be used for potential rapid detection in routine shellfish analysis for the seafood industry. The sector requires simultaneous large-scale sample screenings to monitor contamination levels in processing plants and evaluate the performance of the hazard analysis and critical control point (HACCP) system. PCR-ELISA also proved to be economical, with a cost of about 9 Euros per sample, and the quick assay taking 8h to complete starting from DNA extraction. © 2012 The Authors. Letters in Applied Microbiology © 2012 The Society for Applied Microbiology
Occurrence of norovirus and hepatitis A virus in shellfish
No full textNorovirus (NoV) and hepatitis A virus (HAV) are a common cause of gastroenteritis outbreaks associated with consumption of raw shellfish. The majority of NoV infections worldwide are due to geno group II NoVs. The predominant HAV strains belong to sub -genotype IB. A total of 369 bivalve molluscs (294 mussels, 42 clams and 33 oysters) from several retail points and harvesting class -A areas of the Adriatic basin in South Italy, North Italy and Albania (Butrinti Lagoon) were sampled between 2008-2013. All the samples were screened by a
hemi-nested RT-PCR specific for NoV geno group II and by a nested RT-PCR for the VP1/2A region of HAV. NoV RNA was detected in 10,5% of samples and ranged from 3% in 2008 to 85% in 2013. HAV RNA was detected in 32,5% of samples and ranged from 90% in 2008 to 3,1% in 2013. The marked decrease in HAV prevalence may be the related to the vaccine-induced immunity, able to interrupt the ecological cycle of HAV. Monitoring the epidemiology of the virus strains circulating in the field is pivotal to develop and assess the
efficacy of new control strategies to reduce the risks for public healt
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