Prevalence and pathogenic potential of Arcobacter spp. isolated from edible bivalve molluscs in Sardinia

Abstract

In recent years, Arcobacter spp. has emerged as an important food-borne pathogen. Members of the genus Arcobacter are frequently isolated from foods of various origin, with particular regard of fish and shellfish. However, little epidemiological information is available on the occurrence of the Arcobacter genus and on the virulence potential of strains recovered from edible bivalve molluscs. The present study was aimed to assess the prevalence of Arcobacter spp. in 86 pool samples (59 mussels, 17 oyster and 10 clams) collected from production farms and retail market of Sardinia (Italy). Species identification was conducted by multiplex PCR and PCR-RFLP. In addition, the presence of 9 putative virulence genes (cadF, hecB, pldA, tlyA, cj1349, irgA, mviN, ciaB and hecA) was assessed by PCR assay. The overall prevalence of Arcobacter spp. was 28.8% in mussels, 35.3% in oyster and 40.0% in clams. The most prevalent species were A. cryaerophilus and A. skirrowii detected each in 12.8% of the samples, followed by A. butzleri detected in 10.5% of the samples. The presence of at least one virulence gene was detected in 58.1% of the strains. A. butzleri isolates harbored 8 out of the 9 putative virulence genes (hecB was never detected) while A. cryaerophilus carried 6 virulence genes (cj1349, hecA, mviN, tlyA, hecB and pldA) and A. skirrowii carried 2 virulence genes (cadF and mviN).The present study indicates the potential risk for human health associated to the consumption of edible bivalve molluscs, especially when eaten raw or undercooked. Considered that the bacterial indicator of fecal contamination E. coli is not always a good predictor of the presence of Arcobacter spp. in bivalve molluscs, a specific and continuous surveillance programme should be conducted on these type of shellfish farmed in Sardinia.