Distribution of indicator bacteria and bacteriophages in shellfish and shellfish-growing waters

Abstract

Shellfish (mussels and clams) and shellfish‐growing waters were examined for indicator bacteria according to the EC regulations, Salmonella spp., coliphages and anti‐Salmonella phages. Samples were collected both from natural‐growing areas along the coast and from authorized shellfish‐harvesting beds. The coastal area was affected by organic pollution and extensive faecal contamination and, according to the legal requirements, was unsuitable for shellfish farming. The shellfish collected along the coast also showed faecal contamination at levels which did not conform to legal standards. No significant differences were observed between the frequency of isolation of somatic coliphages and indicator bacteria from sea water. In contrast, both the authorized and wild coastal shellfish were contaminated by coliphages at a significantly higher level than the corresponding bacterial indicators for faecal contamination (χ2 test, P < 0·01). Coliphage concentrations were significantly correlated with faecal indicators in marine waters (P < 0·001) and sediments (P < 0·05), but no correlation was found in shellfish, thus showing their low specificity as indicators of faecal pollution of human origin in shellfish of economic importance.

Microbial contamination and purification of bivalve shellfish: Crucial aspects in monitoring and future perspectives – A mini-review

“…However, coliphages are able to increase their initial effluent discharge number in marine environment and in shellfish. Furthermore, they are not a specific index for pollution with human enteric viruses, as they are found in both human and other animals (Legnani et al, 1998). Male-specific (Fþ) coliphage (group II and III) has been pointed out as providing an additional advantage in distinguishing animal and human fecal pollution (Cole et al, 2003;Scott et al, 2002).…”

Effect of processing and storage conditions on the microbiological quality of minimally processed vegetables

“…In addition to the total heterotrophic counts and the traditional faecal indicators, tests were also made to determine the presence of anti‐ E. coli bacteriophages as indicators of enteroviral contamination (Kott et al. , 1974; Legnani et al. , 1998) and pseudomonads as indicators of bacteria that could affect shelf‐life.…”

Preliminary Study on the Shelf-Life of Shelled Refrigerated Mussels

“…The observed decrease in faecal bacterial load could probably be related to the synergic effect of deep refrigeration and low pH as well as to the presumptive activity of coliphages, whose presence is well known in several bivalves (Legnani et al, 1998). The long shelf-life of shelled bivalves can also be explained by the decrease in sulphide-producing bacteria; this kind of micro-flora increased only for sub-samples Cd8 and Cd10 that exhibited some sensorial modification, demonstrating their spoilage activity also for the studied product.…”