Food safety: Europe’s worst case of e.coli confounds science

Jon Condon, 21/06/2011

Europe’s recent outbreak of e.coli poisoning, which killed 39 people, left 826 stricken with Hemolytic-Uremic Syndrome (HUS), and hospitalised another 3406 is now regarded as the second worst such food safety incident in history.

As recently as two months ago, it was unlikely that people outside the food safety science field had ever heard of E. coli O104:H4 bacteria. That was before the most recent outbreak in Europe, currently linked to contaminated Organic sprouts.

The only larger e.coli event recorded was an O157:H7 strain outbreak in Japan that sickened 12,000 people, according to US industry journal, Food Chemical News.

The World Health Organisation claimed on June 2 that Europe’s recent incident represented a brand new strain of E. coli. However, O104:H4 has been associated with diarrhoea, especially in infants for some years. Usually, it is associated with human-to-human transmission rather than animal-to-human, and it uses a different mechanism to attach to the intestinal tract.

That fact alone makes detection and identification more complicated, according to the US National Meat Association. In fact, none of the currently used commercial testing methodologies could have detected it, NMA said this week.

The big difference in the European outbreak was that in this case, the O104 bacteria picked-up a powerful toxin gene.

Current evidence suggested that the toxin produced by the O104 is the same as that of pathogenic e.coli O157, according to Dane Bernard, vice president of food safety for Keystone Foods. Keystone is one of the world’s largest manufacturers of beef patties, a major supplier to McDonalds Restaurants and other global customers.

Genes that code for toxin were actually encoded on viruses that infect e.coli and become part of the bacterial genome, Dr Bernard said. Under certain conditions these viruses once again took the form of an active virus and could infect other e.coli.

Dr Mohammad Koohmaraie, chief executive of the meat division of IEH Laboratories, told the NMA’s Lean Trimmings report that active research was being undertaken into why the European bug was causing more severe illness at such an increased rate over earlier e.coli outbreaks.

He said the answer may have to do with the efficiency of the attachment mechanism that this strain used.

“It has become increasingly more challenging to tell the pathogens from the non-pathogens and the aspiring pathogens, especially when they seem to trade genes so easily,” Dr Koohmaraie said.


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