Presence of Potentially Infectious Human Enteric Viruses and Antibiotic Resistance Genes in Mussels from the Campania Region, Italy: Implications for Consumer's Safety

Abstract

This study presents a comprehensive assessment of viral contamination and antibiotic resistance genes (ARGs) presence in mussels (Mytilus galloprovincialis) (n = 60) collected from retail stores in the Campania region (Italy). High prevalence of human noroviruses (HuNoV) genogroup I (GI) (77%) and genogroup II (GII) (40%), rotaviruses (RV) (60%), and astroviruses (HAstV) (25%) was found, with average levels of 4.34, 5.09, 5.05, and 4.00 Log genome copies (GC)/g, respectively. All samples tested negative for hepatitis A and E viruses. Viral faecal contamination indicators, including somatic coliphages (88%, 3.62 mean Log plaque forming units (PFU)/100 g) and crAssphage (50%, 3.72 mean Log GC/g), showed strong correlations (ρ > 0.65, p-value < 0.05) with HuNoV GII, HAstV, and RV concentrations in mussels. The study also investigated the presence of respiratory viruses, with all samples testing negative for SARS-CoV-2, respiratory syncytial virus, and influenza A virus.Furthermore, a capsid-integrity RT-qPCR assay was applied to selected positive samples, confirming the presence of potentially infectious viruses and underscoring the associated risks to consumers.Additionally, ARGs were detected by qPCR, targeting beta-lactams, quinolones, and chloramphenicol resistance genes in both the total and the bacteriophage fractions of selected samples.Overall, this study emphasizes the importance of continued surveillance and strategic interventions to mitigate public health risks associated with the consumption of contaminated bivalve molluscan shellfish (BMS), which may imply the dissemination of infectious enteric viruses and ARGs within communities.

Keywords: ARGs; Food safety; Foodborne viruses; Viability RT-qPCR.

Fig. 1

Geographical map of bivalve molluscan shellfish production areas linked to retail samples in the Campania Region, Italy

Fig. 2

Workflow followed to analyse human enteric viruses, respiratory viruses, viral faecal indicators and antibiotic resistance genes (ARGs) in mussel samples. The somatic coliphage count assay was performed using whole mussel homogenates, whereas virus isolation and capsid-integrity assays were conducted on the digestive glands (hepatopancreas) of the mussels

Fig. 3

Spearman rank correlation between levels of human enteric viruses and viral faecal contamination indicators in mussels collected in Italy. HuNoV GI, human norovirus genotype I; HuNoV GII, human norovirus GII; HAstV, human astroviruses; RV, rotavirus

Fig. 4

Performance of viability PCR to discriminate between infectious and thermally inactivated viruses in mussels. S1→S8 samples correspond to M21, M27, M28, M29, M38, M41, M42, and M43 samples, respectively. S1→S8 Ø: samples without PMAxx pretreatment; S1→S8 PMAxx: samples with PMAxx pretreatment. HuNoV GI, human norovirus genotype I; HuNoV GII, human norovirus GII; HAstV, human astroviruses; RV, rotavirus

Fig. 5

Levels of antibiotic resistance genes (ARGs) in the total and the bacteriophage purified fraction of mussels (n = 8) expressed in Log GC/g. Each line represents the median value of each gene