Application and evaluation of digital PCR platforms for same-day detection of Vibrio parahaemolyticus in mussel samples

V. paraha emolyticus infection is a major cause of disease associated with the consumption of raw or undercooked seafood. Given the short shelf life of this type of foods, rapid detection methods are of high interest. To reach this goal, this study compared three different molecular techniques for detecting V. parahaemolyticus from the primary enrichment described in the ISO standard 21872-1:2017. To do so, three different DNA amplification techniques were tested: digital PCR (three different platforms), real-time PCR, and LAMP, with its real-time and colorimetric version. The analysis of spiked mussel samples, following the specific workflows considering target multiplexing capacities of the different platforms, returned an LOD50 of 15.0 CFU/ 25 g after the primary enrichment for qPCR; however, they were all considered negative by digital PCR even though a few positive partitions were observed. This value was improved after the secondary enrichment, allowing to reach 3.3 CFU/ 25 g for qPCR and LAMP strategies. The analysis of natural samples returned minor differences among the different molecular methods. In parallel to the previous study, different chromogenic agars were compared, with Chromagar Vibrio the best one, with the highest specificity, whereas HardyCHROM had the lowest, making it unsuitable when high concentrations of interfering bacteria are expected. This study highlights the importance of appropriate sample processing/ preparation for sensitive and successful performance of molecular methods, as, by itself, the sole sensitivity associated with any given detection technology is not enough for pathogen detection in food matrices.