An ESBL-producing E.coli strain, which is said to be harder to treat than MRSA, now infects about 30,000 people annually in England and Wales, according to a TV Tonight Programme. It is thought imported chicken is closely linked to the presence of this resistant strain.

This E.coli strain produces Extended-Spectrum Beta Lactamase (ESBL), an enzyme which makes it such that infections become resistant to several antibiotic drugs. Patients develop urinary tract infections, which can develop into dangerous septicemia (blood poisoning).

The first case of ESBL E.coli appeared about four years ago and seemed to infect elderly women. As it has spread, so has the age and type of patient who gets infected. It is spreading rapidly throughout England and Wales, according to the program.

Tests carried out recently by the Health Protection Agency found that one quarter of foreign chickens sold in British supermarkets carry ESBL E.coli. Out of hundreds of birds tested, only one chicken farmed in Great Britain was infected. Recent tests carried out in Spain and the USA have also revealed a link between ESBL E.coli and chicken.

The Health Protection Agency (HPA) issued a statement on 22 September, stating that in light of increased media and public interest in ESBL-producing E.coli, it felt it might be helpful to provide some background information about these infections, and also explain what work is being carried out in this area.

What are ESBL-producing E.coli?

ESBL-producing E.coli are antibiotic-resistant strains of E.coli. E.coli are common bacteria which will normally exist innocuously in the gut (intestines). The ESBL-producing strains manufacture an enzyme called extended-spectrum beta lactamase (ESBL). ESBL makes them resistant to cephalosporin antibiotics, as well as a number of other classes of antibiotics – making these infections much more challenging to treat.

ESBL-producing E.coli can cause a wide range of infections, ranging from urinary tract infections to severe blood poisoning. Infections with ESBL-producing E.coli most commonly hit the elderly, people who have recently been in hospital, and people who receive or have received antibiotic treatment. ESBL-producing E. coli are exceptionally uncommon in simple cystitis.

The HPA emphasizes that ESBL-producing E.coli infections are growing globally, and not just in the United Kingdom. The HPA says it is one of the world’s foremost institutions in terms of research into this area.

Since 2003, along with NHS hospital microbiologists, the HPA has been working hard to advise and provide information to GPs and hospitals regarding the treatment and diagnosis of these infections.

The HPA stresses that a great deal of further research is needed to pinpoint the origin of E.coli that cause infections. Even though chicken has been put forward as the reason they have entered the UK, it must be noted that the ESBLs produced in tested chickens are different from the ones found in infected humans. E.coli with ESBLs CTX-M-1; CTX-M-2 and CTX-M-14 have been found in imported chicken meat in the UK. However, most of the ESBL-producing E.coli found in human infections contain the CTX-M-15 ESBL which is not present in chicken samples.

Another suggested source has been migration. The HPA says further research is needed to be able to comment on this. More research is required to find out how many people carry ESBL-producing E.coli in their gut (even though, it must be pointed out that these people will be carrying it harmlessly).

The HPA says the 30,000 per year human infection figure is an estimate, which needs to be verified.

Further information on Extended-Spectrum Beta-Lactamases (ESBLs) (resource no longer available at

Extended Spectrum Beta Lactamases – Frequently Asked Questions (resource no longer available at

Written by: Christian Nordqvist