Foodborne infection by E.coli linked to lethal toxin from virus invasion
deadly food pathogen E coli, scientists in the UK identify the key
event that originally transformed a harmless bacteria into a
transporter of foodborne infection.
Ongoing growth in the global €3.2 trillion food production, processing, distribution and preparation industries has led to growing pressure on the food chain to minimise outbreaks of food borne diseases.
In industrialised countries, the percentage of people suffering from foodborne diseases each year has been reported to be up to 30 per cent.
In the US for example, sixty-one deaths and 73,000 illnesses - such as bloody diarrhoea and haemorrhagic colitis - are blamed on eating foods contaminated with E. coli each year, according to the US Centers for Disease Control and Prevention.
Twenty-three years ago a harmless gut bacterium called E. coli developed the ability to kill people through food poisoning, bloody diarrhoea and kidney failure.
Normally E. coli bacteria live in the intestine and do not pose any danger, but some varieties can cause fatal food poisoning. The most serious in the UK is E. coli O157, which is carried by livestock (mainly cattle), and can enter the human food chain through contaminated meat and inadequate food processing.
According to Dr Heather Allison, from the University of Liverpool's school of biological sciences, this is due to a lethal poison that entered the bacteria over 20 years ago.
"Sometime before 1982 an unknown virus that attacks bacteria passed on a part of genetic coding to E. coli that allows some strains to make Shiga toxin," she says.
This lethal poison causes the notorious food-borne infection that results in bloody diarrhoea and sometimes kidney failure in people, she adds.
The team in Liverpool has now discovered how the virus can infect E. coli, by recognising a newly identified but common receptor on the surface of E. coli cells, which allows the viruses to gain entry into the bacteria.
Once inside, the virus gives new genetic material to the bacterium, providing it with the ability to produce Shiga toxin.
Echoing standard understanding in the food industry, the UK scientists re-ierated that the risk of E.coli poisoning can be reduced: by avoiding undercooked minced beef; foodstuffs in general that have come into contact with livestock faeces and have not been cooked or properly washed; untreated water contaminated with livestock faeces; and cooked foodstuffs that have come into contact with contaminated, uncooked meat products.