Enumeration of <em>Escherichia coli</em> and determination of <em>Salmonella</em> spp. and verotoxigenic <em>Escherichia coli</em> in shellfish (<em>Mytilus galloprovincialis</em> and <em>Ruditapes decussatus</em>) harvested in Sardinia, Italy

Abstract

The aim of the present study was to evaluate the occurrence of Salmonella spp., Verotoxigenic E. Coli (VTEC) and enumerate E. coli in shellfish (Mytilus galloprovincialis and Ruditapes decussatus) collected before and after depuration from two class B harvesting areas located in Sardinia (Italy). All the samples were analyzed for Salmonella spp. detection according to European Commission Regulation (EC) 2073/2005 and examined using the five tube Most-Probable-Number (MPN) method for enumeration of E. coli in accordance with the European Union reference method ISO 16649-3:2015. E. coli VTEC was investigated following a direct multiplex Polymerase Chain Reaction (PCR) screening test. The enumeration of E. coli met the European law limit for Class A areas of 230 MPN/100g. The averaged enumeration of E. coli in samples of M. galloprovincialis and R. decussatus collected at the harvesting time was 39 and 37 MPN/100 g respectively. The average contamination levels in samples collected after purification were 58 MPN/100g (M. galloprovincialis) and 32 MPN/100 g (R. decussatus). E. coli VTEC was not detected, on the contrary, Salmonella ser. Typhimurium was detected in one sample of M. galloprovincialis and in one sample of R. decussatus collected at the harvesting time. No significant associations were observed between E. coli levels in shellfish and environmental parameters of water or with the detection of Salmonella ser. Typhimurium in M. galloprovincialis and R. decussatus samples. Nevertheless, the occurrence of Salmonella ser. Typhimurium, involved in human infection outbreaks, should be considered a potential risk for consumers.

Serotyping and Evaluation of Antimicrobial Resistance of Salmonella Strains Detected in Wildlife and Natural Environments in Southern Italy

“…Enterica was the dominant subspecies and was isolated in all animals except frogs. Enterica was the only subspecies detected in shellfish, as already reported by [ 16 ], while in the other samples, five non- enterica subspecies were found. In contrast to the study in [ 6 ], the prevalence of enterica subspecies in mammals was higher than that of non- enterica subspecies.…”

Molecular Characterization and Antibacterial Resistance Determination of Escherichia coli Isolated from Fresh Raw Mussels and Ready-to-Eat Stuffed Mussels: A Major Public Health Concern

“…Similarly, Sferlazzo et al (2018) [39] mentioned that E. coli contamination tended to be lower during the summer season. In a study conducted in Italy, E. coli was detected in all samples of M. galloprovincialis and Ruditapes decussatus [40]. In another study conducted in Italy, which examined 600 raw mussels, E. coli was detected in 3.5% of the samples [41].…”