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Listen to this siteFriday 30 April 2004
This research project intends to establish optimum methods for the detection of C. parvum , E. coli and campylobacter in UK shellfish and evaluate the effectiveness of commercial purification.
Study Duration : September 2000 to December 2002
Contractor : University of Aberdeen
Shellfish, specifically bivalve molluscan shellfish, such as oysters and mussels, are filter feeders which have the ability to concentrate and retain micro-organisms. Some of these are pathogenic to humans and are of particular concern if the shellfish is consumed either raw or undercooked. Monitoring the hygienic status of UK shellfish is currently limited to Salmonella spp. and E. coli . However, the presence of other specific pathogens (e.g. Vibrio parahaemolyticus , Cryptosporidium parvum and E. coli O157) is unknown due to the limited sensitivity and specificity of conventional methods used in present surveillance exercises.
New methods for the presence and enumeration of several pathogenic micro-organisms are now available, in particular for Vibrio parahaemolyticus , Cryptosporidium parvum and E. coli O157. Their use will allow the shellfish industry and consumers to better assess product safety. While Vibrio parahaemolyticus is sometimes implicated in UK food poisoning, the true pathogenic status of isolates is unknown and requires verification. Prior to consumption, numbers of micro-organisms in shellfish from class B harvesting areas can be reduced by a process called depuration which involves placing the shellfish in a tank through which seawater is continually re-circulated via an integral UV lamp that kills the bacteria washed free from the shellfish. The effectiveness of this commercial process on removal of C. parvum , E. coli O157 and campylobacter was assessed.
This project established optimum methods for the isolation and detection of Vibrio parahaemolyticus , Cryptosporidium parvum and E. coli O157 in shellfish.
A 12 month survey was conducted to estimate the prevalence of E. coli O157 in UK grown shellfish using the optimum isolation method. The results of the survey revealed that E. coli O157 was not found in any of the 236 samples of UK shellfish tested.
Depuration is the process where contaminated shellfish can be purified by placing them in tanks of clean seawater under controlled conditions. The shellfish are able to continue the natural filter-feeding process and flush out any micro-organisms. Depuration studies revealed that depuration for 42 hours is effective in reducing V. parahaemolyticus 100-fold, however studies on C. parvum and Campylobacter spp. require further validation.
Final report is available from the FSA Library and Information centre. To obtain a copy, please contact the Enquiry Desk, Dr Elsie Widdowson Library and Information Services, Food Standards Agency ( Tel: +44 (0) 20 7276 8181/8182 or by e-mail to: library&info@foodstandards.gsi.gov.uk ).
Contact
:
Email
: science@foodstandards.gsi.gov.uk
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