Escherichia coli

What is Escherichia coli?

Escherichia coli

Escherichia coli is a gram negative bacterium that is a member of the normal gut flora of humans and animals.

However, many E. coli carry virulence factors which enable them to be pathogenic in target hosts. These pathogenic E. coli are implicated in a number of diseases including diarrhoea, septicaemia and urinary tract infections in humans and animals.

Of particular interest are E. coli with zoonotic potential such as VTEC O157:H7 which is carried mainly by ruminants as a commensal, but can cause severe disease in susceptible humans. Humans are usually infected from consumption of contaminated meat or via direct contact with infected farm animals and their environments.

Research

During the last ten years, VLA has been working with farmers, private veterinary practices and abattoirs all over England and Wales to investigate the epidemiology of VTEC O157 in cattle.

VLA's research focuses on the understanding of the pathogenesis of E. coli and to determine what virulence factors are essential for pathogenesis and how these factors interact with the host.

Surveillance

Surveillance for E. coli is carried out using endemic disease submissions. It is based on standardised and accredited testing criteria to:

  • investigate associations with specific disease syndromes
  • monitor and identify potential new and emerging zoonotic E. coli strains
  • provide effective year-on-year comparisons to identify trends of E. coli in farm animals.

VTEC O157 is still the most important human pathogen in England and Wales, but the zoonotic and endemic disease potential of other VTEC serogroups is monitored carefully.

VLA carries out investigations to trace sources of human VTEC outbreaks on request of the Health Protection Agency, if a link with farm animals is suspected. For example, the major outbreak of E. coli O157 in Surrey in 2009.

Antimicrobial resistance patterns are monitored regularly with a particular interest in detecting emerging extended-spectrum beta-lactamase enzymes (ESBLs).

VLA publications

Health & Safety Executive