05.09.16 Global Superbugs

Antibiotic resistant E.coli found in one in four samples of supermarket chicken

One in four samples of chicken from the UK’s largest supermarkets contains antibiotic-resistant E.Coli bacteria, new research has revealed.

The bacterium was found in meat from Asda, Aldi, Co-op, Morrisons, Sainsbury’s, Tesco and Waitrose, Cambridge University researchers found.

They tested whole chickens, breast meat, legs, drumsticks, thighs and chicken sausages – and found 24% contained types of E. Coli resistant to antibiotics.

And 51% of E. Coli found in pork and chicken from the supermarkets were resistant to the antibiotic trimethoprim, a drug used to treat more than half of bladder infections.

The findings illustrate how antibiotic use in farm animals – and not simply doctors overprescribing the drugs to patients as many believe – is contributing to growing levels of drug resistance, which is why the Bureau of Investigative Journalism (TBIJ) has been probing this under-reported topic for six months.

The problem of antimicrobial resistance is now so severe NHS England’s chief medical officer Dame Sally Davies said it remains a ‘bigger threat than terrorism’ – despite commissioning a report five years ago to tackle the issue.

In fact, this year a Government-backed report by economist Professor Jim O’Neill predicted the problem would kill 10 million people worldwide by 2050 – more deaths than cancer.

Figures published earlier this year by the Vetinary Medicines Directorate and analysed by the Bureau revealed an increase in sales of some critically important antibiotics – those that doctors now rely on to treat infections because drug resistance has left others medicines less effective – for veterinary use.

This is despite the fact it is now known that resistant forms of certain food poisoning illnesses, including campylobacter, and some variations of the superbug MRSA, are directly linked to antibiotic use on farms.

In April, the Bureau revealed growing levels of resistance among Campylobacter bacteria – which reports show is commonly found in supermarket chickens.

Previously unpublished data collated by Public Health England showed almost one in two of all human campylobacter cases tested in England was resistant to ciprofloxacin.

Ciproflaxin is one of several drugs doctors can turn to when victims of food poisoning develop complications.

An earlier Bureau investigation had uncovered how UK poultry producers were continuing to use significant quantities of fluroquinolones, a class of antibiotics banned in poultry production in the US, despite concerns over the health risks to humans.

Fluroquinolones are feared to be fuelling drug resistant forms of superbugs causing food poisoning in humans, including campylobacter, salmonella and E. Coli.

Figures compiled by the British Poultry Council (BPC) – previously unpublished and obtained by the Bureau – revealed its members increased their use of the drugs, using 1.126 tonnes of fluoroquinolones in 2014 compared with 0.71 tonnes in 2013.

Industry data released after the investigation showed a 48% drop in 2015 compared to the British Poultry Council, which says it is committed to reducing antibiotic use.

In response to the new research by Cambridge University, the Alliance to Save our Antibiotics, who commissioned the new study, called on supermarkets to take urgent action to reduce antibiotic use in their supply chains.

Cóilín Nunan, the group’s scientific advisor, said: ‘Scientific evidence is accumulating that the overuse of antibiotics on farms is an important contributor to antibiotic resistance in E.coli infections.

‘E.coli is now killing more than twice as many people as MRSA and Clostridium difficile combined, so the price of any further inaction will be measured in human lives.’

E.Coli kills more than 5,500 people a year in England. It is associated with deadly food poisoning, bloodstream infections and urinary tract infections.

If more bacterium become resistant to the drugs used to treat them thousands more people could become ill and die.

The researchers looked at 97 samples of pork and 92 sample of chicken.

They found E.Coli bacteria in 186 (98%) of samples.

The team found 24% of chicken samples tested positive for ESBL E. Coli (extended-spectrum beta-lactamase E. coli) which is resistant to cephalosporin antibiotics.

Cephalosporin drugs are considered ‘critically important’ as they are one of the last lines of defence against treating serious E.coli blood-poisoning and kidney infections.

Additionally, 20% of chicken samples and 18% of pork samples tested positive for bacterium resistant to gentamicin.

Gentamicin is widely used to treat serious upper urinary-tract infections (those of the kidney or the ureters (the tubes connecting the kidneys to the bladder).

And 52% of pork and 50% of E. Coli was resistant to trimethoprim, used to treat more than half of bladder infections.

Finally, 36% of chicken samples and 23% of pork samples contained bacteria resistant to amoxicillin, a drug which was commonly used to treat urinary tract infections until the strain of bacteria became resistance.

The Bureau contacted the supermarkets involved but most declined to comment – adding it is an ‘industry-wide’ problem.

Co-op was the only supermarket to respond. In a statement, it said: ‘Animal welfare and food safety are priorities for our business.

‘We don’t allow the use of antibiotics in any of our meat and poultry, unless there is written approval of a vet to help treat a specific health issue with an animal, and their use as a preventive measure is not permitted.’

A Food Standards Agency spokesperson said the health risk from drug resistant bacteria in meat is low if it is handled and cooked properly.

He said: “Poultry, pork, and minced beef and lamb products should be cooked thoroughly so that the meat is steaming hot throughout, there is no pinkness and any juices run clear.

“AMR is a significant threat to public health in the future and consumer safety is a priority for the FSA. Working with others across Government, and with food producers, we aim to reduce the use of antimicrobials in food production animals.

“An important part of that will be work with food manufacturers, assurance schemes and retailers to develop standards for the responsible use of antibiotics in poultry, pig and dairy sectors.”



Modern cephalosporins are classified by the World Health Organisation as critically important in human medicine and are used for treating human E. Coli blood-poisoning infections and upper kidney infections.

Coli resistant to modern cephalosporins are called ESBL E. coli (extended spectrum beta-lactamase E. coli).

Of the 92 chicken samples, 22 tested positive for ESBL E. coli (24%).

ESBL-positive samples were found from all supermarkets:

  • 5 from Asda
  • 4 each from the Co-op and Sainsbury’s
  • 3 from Aldi
  • 2 each from Morrisons, Tesco and Waitrose.

ESBL-positive samples included chicken thighs, legs, drumsticks, diced breasts, wings and sausages.


Gentamicin is very widely used for treating E. coli upper urinary-tract infections in humans.

In total 35 meat samples (19%) were positive for gentamicin-resistant E. coli.

This included 18 of 92 (20%) chicken-meat samples and 17 of 97 (18%) pork samples.

Gentamicin-resistant E. coli was found on meat from all supermarkets:

  • 9 from Tesco
  • 7 from Aldi
  • 6 from Waitrose
  • 4 each from ASDA and the Coop
  • 3 from Morrisons
  • 2 from Sainsbury’s.


Trimethoprim is the most common treatment for lower E. Coli urinary-tract infections in humans, used in over 50% of cases.

In total 97 (51%) meat samples were positive for trimethoprim-resistant E. coli.

This included 50 of 97 (52%) pork samples and 47 of 92 (51%) chicken-meat samples.

Trimethoprim-resistant E. coli was found on meat from all supermarkets:

  • 16 from Asda and Morrisons
  • 14 each from the Co-op and Tesco
  • 13 each from Aldi and Sainsbury’s
  • 11 from Waitrose.


Ampicillin used to be routinely used for treating human urinary-tract infections, but is no longer used because of high levels of resistance.

Similarly, amoxycillin is being undermined as a suitable treatment for urinary infections due to resistance.

As a result, amoxicillin is often given in combination with clavulanic acid which helps combat the bacterial resistance.

In total 54 (29%) meat samples were positive for ampicillin-resistant E. coli.

This included 33 of 92 (36%) chicken-meat samples and 22 of 97 (23%) of pork samples.

Just one chicken-meat sample was fully resistant to amoxicillin/clavulanic acid, and one further chicken-meat sample showed intermediate-level resistance.