June 6, 2011

ongoing expert reaction to E. coli outbreak in Germany

Experts comment on the latest developments.

Dr Paul Wigley, from the University of Liverpool’s School of Veterinary Science, said:

“Beansprouts are not an uncommon cause of food poisoning. Both the CDC and the US Department for Agriculture have long been concerned about the risks of bacterial contamination of water used in their production. Both E. coli and Salmonella outbreaks have been linked to sprouts (Mung Bean and Alfalfa) in the US and in the UK (there was a significant Salmonella outbreak last October linked to beansprouts at a Jewish Wedding in Manchester).”

Prof Sally Bloomfield, Honorary Professor at the London School of Hygiene and Tropical Medicine, and Chair of the International Scientific Forum on Home Hygiene, said:

“For anyone who has not travelled recently to Germany, there is very little risk. For anyone returning from Germany who is infected or thinks they might be infected, it is important to make sure they do not infect other family members or contacts. This means good hygiene – the same as for any stomach bug. The most important thing is to wash hands thoroughly, particularly after visiting the toilet, and before eating or preparing food. Also make sure the toilet, and hand touch surfaces in the toilet, are kept cleaned and disinfected.”

[The IFH also has a factsheet on what people can do in their homes to minimise risk from E. coli, which is based around the related strain O157 – the factsheet is available at this link and the background to it is here.]

Dr Stephen Smith, Lecturer in Clinical Microbiology at Trinity College Dublin, said:

“E. coli that causes HUS has been shown to bind to Alfafa sprouts before in a laboratory situation. This requires a protein on the bacterial surface called OmpA. Indeed, sprouts were implicated in an outbreak in Michigan and Virginia in 2005. E. coli (and indeed Salmonella) can stick tightly to the surface of seeds needed to make sprouts and they can lay dormant on the seeds for months. During germination the population of bugs can expand 100,000 fold. However, and this is probably the key to the German outbreak, the bacteria are inside the sprout tube as well as outside. Thus washing probably had no effect. The bottom line is that it is crucial to source where the seeds came from and recall any stock. Furthermore, it would be essential in the future to test seeds sent to nurseries and indeed consumers.

“In 1997 there was an outbreak of E. coli causing bloody diarrhoea and HUS in Michigan. In common with the current outbreak, younger females were disproportionally affected (68% were female, and the median age was 31 years). Source: http://www.cdc.gov/ncidod/eid/vol7no6/breuer.htm#11.”

Prof Paul Hunter, Professor of Health Protection at the University of East Anglia, said:

“The big issue today is the claim that the outbreak can be traced back to bean sprouts. I do not know what the evidence base is behind this statement. I have also been told that the source farm has been identified, though again I do not know on what basis this has been done.

“Bean sprouts are a likely cause of food poisoning. There have been many outbreaks associated with bean sprouts reported in the literature, especially in the US. Hopefully over coming days we will find out how this farm, if confirmed, was implicated and what was the most likely cause of the contamination.”