Retail survey of Listeria monocytogenes in smoked fish

Between July and November 2006, 3,226 samples of ready-to-eat hot and cold smoked fish were sampled from over 1,000 retail premises within the UK, of which 3,222 samples were acceptable for testing. The prevalence of L. monocytogenes in ready-to-eat smoked fish sold in retail premises in the United Kingdom was measured. The presence of Listeria spp., Salmonella spp., Escherichia coli, coagulase positive staphylococci and Enterobacteriaceae was also investigated and salt, pH and water activity were measured.

Of the 1,344 samples of cold smoked fish tested, 282 (20.5%) contained Listeria spp.; 236 (17.4%) were L. monocytogenes which was present below the 100 cfu/g legal limit.

Of the 1,878 samples of hot smoked fish tested, 96 (5.2%) contained Listeriaspp.; 66 (3.4%) were L. monocytogenes. Three of these samples (0.06%) were in breach of the limits (>100 cfu/g) for L. monocytogenes as laid down in the Microbiological Criteria Regulations. The Agency took appropriate action as soon as the results for these samples were reported and the product was withdrawn from retail sale.

Salmonella was not detected in any of the samples tested. Only 7 samples contained E. coli (threshold for detection was 10 cfu/g); 13 samples contained coagulase positive staphylococci (threshold for detection was 10 cfu/g). Of the 3,222 samples taken, 587 samples contained levels of Enterobacteriaceae ranging from 10cfu/g to 106cfu/g. There was a significant correlation between the detection of Enterobacteriaceae and detection of Listeria spp. (p<0.001).

• Prepacked and loose ready-to-eat smoked fish were sampled at retail.
• 378 samples contained Listeria spp. Most of the listeria species detected were L. monocytogenes.
• 302 samples contained L. monocytogenes of which 99.3% were within legislative limits.
• Three hot smoked fish samples (0.06%) breached the limits for L. monocytogenes laid down in the Microbiological Criteria Regulations. Immediate action was taken by FSA to withdraw the products from retail.
• No salmonella was detected in any of the samples tested.
• Variations were found in storage temperatures at retail ranging from -14°C to 13.3°C.

The full technical report is available on foodbase at the link below.