APA News

  • Edinburgh Food Examiners Find Cause of Salmonella Outbreak


    A little known function of Public Analysts is that they can act as Food Examiners under the Food Safety Act. Food examiners microbiologically check food to ensure its safety and quality by testing for indicator bacteria and human pathogens such as salmonella and E. coli O157.

    Recently food examiners at Edinburgh Scientific Services played a key role in solving a sporadic outbreak of Salmonella bareilly across the UK which affected at least 250 people. As the number of infections rose without any obvious source an outbreak team was set-up by the HPA in Lancashire after a number of cases at a wedding in Manchester. There was no obvious pattern to the outbreak until a further cluster of six infections were reported in and around Edinburgh. Investigation of meal histories by local Environmental Health Officers narrowed the search to two suppliers of prepared salad and bean sprouts.

    Microbiology staff at Edinburgh Scientific Services isolated Salmonella bareilly from one of the samples of bean sprouts. This isolate was found to be indistinguishable from the hospital clinical isolate and so helped solve the mystery of what the source of the outbreak had been. The level of salmonella in the sample at 2 colonies per 25 gram of food was extremely low, but was detected by the sensitive methods used by Edinburgh Scientific Services. Further investigation found that the bean sprouts were sold wholesale across the UK via a number of suppliers including fruit markets which explained why it had been difficult to pinpoint the source. The contaminated bean sprouts were also marked cook before use. However in the Edinburgh cases they had been mixed into a salad without prior cooking. No action was taken against the supplier.

    Staff at Edinburgh Scientific Services are shown preparing microbiology plates.