Determination of Salmonella spp., E. coli VTEC, Vibrio spp., and Norovirus GI-GII in Bivalve Molluscs Collected from Growing Natural Beds in Sardinia (Italy).

Marta Marceddu,Sonia Lamon,Domenico Meloni,Sara Ciulli,Simonetta G Consolati,Roberta Mazza,Anna Mureddu

doi:10.3390/foods6100088

Marta Marceddu, Sonia Lamon + Show 5 more

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https://doi.org/10.3390/foods6100088

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Abstract

The aim of the present study was to evaluate the presence of Salmonella spp., verotoxigenic E. coli (VTEC), Vibrio spp., and Norovirus GI-GII in bivalve molluscs, cockles, and European grooved carpet shells (Cerastoderma spp. and Ruditapes decussatus) collected from a class B growing natural bed in Sardinia (Italy). All of the samples were analysed for Salmonella spp. detection according to European Commission Regulation (EC) 2285/2015. Detection and enumeration of Vibrio spp. were performed according to previously published methods. Presumptive identification of Vibrio spp. isolates was performed by means of conventional biochemical tests. E. coli VTEC was isolated following a direct multiplex polymerase chain reaction (PCR) screening test. Norovirus GI and GII were determined by reverse transcriptase-polymerase chain reaction (RT-PCR). No Salmonella spp. were detected. The prevalence of Vibrio spp. was 90%, and the average contamination levels were 3.19 ± 1.07 and 2.84 ± 0.31 Log10 cfu/g in cockles and European grooved carpet shells, respectively. The prevalence of E. coli VTEC was 6.6%. All of the isolates showed a complete pathogenicity profile. The presence of Norovirus was highlighted in 25% of European grooved carpet shells samples. Results showed the typical microbiological profile of bivalve molluscs collected from backwaters and confirmed the capability of shellfish to accumulate E. coli VTEC, pathogenic vibrios, and Norovirus. The presence of such pathogens in shellfish is of major concern for the safety of consumers.

Highlights

Foodborne zoonoses associated with the consumption of bivalve molluscs are reported worldwide [1,2,3,4]
The results of the present study showed the typical microbiological profile of bivalve molluscs collected from backwaters and confirmed the capability of shellfish to accumulate E. coli verotoxigenic E. coli (VTEC), Norovirus, and pathogenic vibrios
Shellfish harvested from coastal areas near agricultural environments are at high risk of pollution of agro-zootechnical origin and may be contaminated by E. coli VTEC transferred from contaminated animals to watercourses [21]

Summary

Introduction

Foodborne zoonoses associated with the consumption of bivalve molluscs are reported worldwide [1,2,3,4]. Shellfish contamination occurs because they are suspension feeders that selectively filter and concentrate small particles of phytoplankton, zooplankton, and the contaminant substances associated with them: bacteria of faecal origin and pathogens adapted to the marine environment, viruses, algal biotoxins, and chemicals [5,6,7,8]. Viruses and naturally occurring vibrios are the most often cited causative agents of disease and death related to shellfish consumption [1,5,9]. Salmonella spp. is considered one of the most common causes of human gastroenteritis [10], the risk of foodborne diseases associated with mollusc consumption is low compared to viruses and naturally occurring vibrios [11]. The incidence of foodborne outbreaks associated with the consumption of shellfish contaminated with Norovirus and pathogenic vibrios is increasing, in many European.

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