Seafood products are widely consumed all around the world and play a significant role on the economic market. Bacteria of the Vibrio genus can contaminate seafood and thus pose a risk to human health. Three main Vibrio species, V. cholerae, V. parahaemolyticus and V. vulnificus, are potentially pathogenic to humans. These species are responsible for a dramatic increase of seafood-borne infections worldwide. Hence, early detection of total and pathogenic Vibrio is needed and should rely on quick and effective methods. This review aims to present the standard methods FDA-BAM, ISO/TS 21872-1:2007 and TS 21872-2:2007 and compare them to recent molecular biology methods including endpoint PCR, quantitative real-time PCR (qPCR) and PCR-derived methods with a focus on LAMP (loop-mediated isothermal amplification). The available methods presented here are dedicated to the detection and identification of the Vibrio species of interest in seafood.

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Aim:  To assess the effect of different foods, which have been implicated or not in cases of listeriosis, on the in vitro virulence‐associated phenotype level of different Listeria monocytogenes strains. Methods and Results:  The virulence‐associated phenotype level of L. monocytogenes was studied with the in vitro cell test based on a plaque‐forming assay with a human adenocarcinoma cell line (HT‐29) monolayer. Three strains of L. monocytogenes were grown in preparations (homogenate, 1‐μm filtrate or 0·2‐μm filtrate) of different food extracts [‘rillettes’ (potted minced pork), milk, raw salmon and cold‐smoked salmon] or in a control medium, brain heart infusion (BHI). The bacterial suspensions grown in food extracts or in BHI at 37°C were diluted with their growth medium (food extract or BHI) or with minimum essential medium before seeding on confluent HT‐29 cell monolayers. Filtration of food extracts had no significant effect on the plaque numbers formed by the bacteria. A significant decrease in the plaque numbers was noted for the three strains when they grew in the rillettes extracts, compared with the other food extracts and BHI. The levels of in vitro virulence‐associated phenotype of the strains after growth in the rillettes extract were similar to or lower than that of the hypovirulent internal reference strain L. monocytogenes 442. After growth in milk and cold‐smoked salmon, the impact on virulence‐associated phenotype depended on the strain. In contrast, plaque‐forming assay indicated increased virulence‐associated phenotype when the strains were switched from a nutrient‐rich medium (food extract or BHI) to a minimum essential medium. Conclusions:  In vitro virulence‐associated phenotype level of the studied strains grown in BHI or cold‐smoked salmon was the same as the control virulent strain EGD. In contrast, the nutrients present in rillettes may therefore substantially reduce the number of plaques but not the growth of L. monocytogenes. The utilization of minimum essential medium as diluent attenuates changes the effect of the food extract on virulence‐associated phenotype in vitro. Significance and Impact of the Study:  In the experimental design of this study, we showed that the nature of the food could affect the in vitro virulence‐associated phenotype level of L. monocytogenes.

Globally, vibrios represent an important and well-established group of bacterial foodborne pathogens. The European Commission (EC) mandated the Comite de European Normalisation (CEN) to undertake work to provide validation data for 15 methods in microbiology to support EC legislation. As part of this mandated work programme, merging of ISO/TS 21872-1:2007, which specifies a horizontal method for the detection of V. parahaemolyticus and V. cholerae, and ISO/TS 21872-2:2007, a similar horizontal method for the detection of potentially pathogenic vibrios other than V. cholerae and V. parahaemolyticus was proposed. Both parts of ISO/TS 21872 utilized classical culture-based isolation techniques coupled with biochemical confirmation steps. The work also considered simplification of the biochemical confirmation steps. In addition, because of advances in molecular based methods for identification of human pathogenic Vibrio spp. classical and real-time PCR options were also included within the scope of the validation. These considerations formed the basis of a multi-laboratory validation study with the aim of improving the precision of this ISO technical specification and providing a single ISO standard method to enable detection of these important foodborne Vibrio spp.. To achieve this aim, an international validation study involving 13 laboratories from 9 countries in Europe was conducted in 2013. The results of this validation have enabled integration of the two existing technical specifications targeting the detection of the major foodborne Vibrio spp., simplification of the suite of recommended biochemical identification tests and the introduction of molecular procedures that provide both species level identification and discrimination of putatively pathogenic strains of V. parahaemolyticus by the determination of the presence of theromostable direct and direct related haemolysins. The method performance characteristics generated in this have been included in revised international standard, ISO 21872:2017, published in July 2017.