The E.coli bacteria is more likely to be spread through poor toilet hygiene than undercooked meat or other food, according to new research.
Scientists, including a team from the University of East Anglia, have found a majority of superbug infections associated with E.coli are caused by harmful strains found in human faeces rather than ones present in chicken, pork or other types of meat.
The researchers looked at a particular E.coli strain which produces an enzyme known as the Extended Spectrum Beta-Lactamase (ESBL) that makes it resistant to antibiotics.
Analysis showed there was “little crossover” of ESBL-producing E.coli from animals to humans.
The team says their findings, published in the journal The Lancet Infectious Diseases, suggest these superbugs “are spread through poor toilet hygiene, not undercooked chicken or other food”.
Professor David Livermore, from the University of East Anglia’s Norwich Medical School, who is the study’s main author, said: “The great majority of strains of ESBL-E.coli causing human infections aren’t coming from eating chicken, or anything else in the food chain.
“Rather – and unpalatably – the likeliest route of transmission for ESBL-E.coli is directly from human to human, with faecal particles from one person reaching the mouth of another.”
E.coli is the most common cause of blood poisoning, with more than 40,000 cases each year in England alone, according to Prof Livermore.
Around 10% of these cases are caused by highly resistant strains with ESBLs, he said.
These bacteria often normally live in the intestines of healthy people and animals and while most varieties are harmless, some strains can cause food poisoning, urinary tract infections and, in worst case scenario, bloodstream infections.
To find out how these superbugs are spread, the researchers sequenced the genomes of ESBL-producing E.coli from humans, extracted from human bloodstream infections, human faeces and human sewerage, as well as meat, taken from beef, pork and chicken.
They found that ESBL-E.coli strains extracted from the human samples were similar to one another but differed to the strains present in animals.
This meant there was little crossover of ESBL-E.coli from animals to humans, the researchers said.
But, they added, it is important to follow good hygiene practices while cooking food as “there are plenty of important food-poisoning bacteria, including other strains of E.coli” that can be picked up through food.
Prof Livermore added: “Here – in the case of ESBL-E.coli – it’s much more important to wash your hands after going to the toilet.”
Commenting on the research, professor Neil Woodford, of Public Health England, said: “In order to tackle antibiotic resistance, we not only need to drive down inappropriate prescribing, but reduce infections in the first place.
“In order to limit serious, antibiotic resistant E.coli bloodstream infections, we must focus on thorough hand washing and good infection control, as well as the effective management of urinary tract infections.
“Prudent use of antibiotics is essential in both animals and humans. Antibiotics are a finite resource. We need them to continue to work when we get sick.”