Investigations into multi-drug resistant ESBL-producing Escherichia coli strains causing Infections in England

1. Executive summary and recommendations

1.1  Since 2003, new highly resistant strains of the bacterium Escherichia coli have become widespread in England and parts of Northern Ireland . These strains of E. coli are able to destroy a large number of common antibiotics, making the infections they cause very difficult to treat. The bacteria produce enzymes called extended-spectrum β-lactamases (ESBLs) that destroy, and confer resistance to, antibiotics. ESBL-producing microbes are not new, having first been recognised in the 1980s. But the new strains produce a particular type of ESBL, the CTX-M type, which is able to break down a wider range of antibiotics. These strains were unrecorded in the UK prior to 2000. They have spread rapidly since 2003, causing infections such as urinary tract infections (UTIs) in hospital patients as well as those treated in the community. The emergence of CTX-M types is a concern for several reasons, outlined below. This report describes investigations carried out by the Health Protection Agency and recommends further action.

1.2  Infections with ESBL-producing E. coli are occurring in both community and hospital patients. Earlier ESBLs-not belonging to the CTX-M family-were largely identified in another bacterium, Klebsiella, and were almost exclusively associated with hospitalised patients, mostly in specialised care.

1.3  CTX-M β-lactamases have spread extensively in E. coli in England in a short period of time.

1.4  Most CTX-M-producing E. coli are exceptionally resistant to multiple antibiotics. These include penicillins and cephalosporins, two of the most important and widely used classes of antibiotics. As a result, there are very limited options for oral treatment for mild to moderate infections. One option, fosfomycin, is not readily available in the UK. Serious infections require the use of very powerful antibiotics, such as carbapenems.

1.5  Early epidemiological studies revealed that a number of patients (often elderly and with serious illness) who became infected with CTX-M-producing E. coli had subsequently died. An independent clinical analysis of 54 patients who died in hospital, and who had a history of infection or colonization with ESBL-producing E. coli, concluded that these organisms had contributed directly to the death of 10 patients (19 per cent). In a further four cases there was some evidence that infection may have contributed to death, but it was not conclusive. Most of the patients were elderly and had one or more potentially fatal diseases.

1.6  An Agency survey in 2004 found that many diagnostic laboratories were using methods that would not detect CTX-M-producing E. coli and would result in inappropriate advice being given to doctors. In addition, only half of the laboratories that had investigated ESBL producers had submitted samples to the Agency's Reference Laboratory for further characterisation. Just two of these laboratories had reported these as 'serious untoward incidents'. Guidelines issued by the Agency in 2004 have substantially rectified the testing/detection issues, as confirmed by a follow-up survey in 2005.

1.7  There is evidence that ESBL-producing bacteria are carried in faecal matter, which may imply spread via the food chain, thereby producing a reservoir of multi-resistant bacteria in the gut that may then cause urinary infections in vulnerable patients.

1.8  Summary recommendations