ESBL attribution (looking for the sources of antibiotic resistance in humans)

Much information is needed to ensure that the right measures are taken and people in the Netherlands can still be treated with antibiotics to counter bacterial infections.

The bacteria themselves are not responsible for the fact that antibiotics are no longer working; this is down to particular enzymes that the bacteria produce. These so-called ESBLs (extended spectrum bata-lactamases) are able to break down antibiotics. The ESBLs are not only common in Dutch livestock farming, but also in humans, who can be carriers. The enzymes are also thought to occur in the environment.

ESBLs are becoming increasingly common in humans and animals. They have been identified in and outside various layers of the healthcare system since 2004. A fast and synchronous increase has also been noted among farm animals. Possible sources of these ESBLs will be explored on the basis of the genetic links between isolates in humans, animals and animal products. The part played by the livestock farming sector and animals in general in this public health problem is still unclear, as are the main transmission routes to humans.

Envisaged results:

  • To determine the part that various animal production chains (pigs, poultry, cattle, calves), and links within these chains, play in exposing humans to ESBLs.
  • To prioritise the part that these chains play in exposing humans to ESBLs. Exposure via other sources (human-human contact, pets, hospitals, travel, food imports, etc.) will also be included.
    • direct (via animal and plant-based foods, for example)
    • indirect (via contact with animals, products, environment)
  • To determine the effect of reductions (prevalence or numbers) of ESBLs in these chains on the pressure on the product, and therefore on the exposure and health effects for the human population.
  • Activities will be expanded in the future to obtain broader-based information about the molecular epidemiology of antibiotic resistance in general, to develop specific intervention possibilities and to set standards.

Various analyses will be used to determine which levels of infection in the sources can be accepted, without putting humans at risk.

Parties involved:

  • Wageningen Bioveterinary Research;
  • Utrecht University  - Institute for Risk Assessment Sciences (IRAS);
  • Utrecht University – Faculty of Veterinary Medicine, Department of Infectious Diseases and Immunology;
  • Utrecht University – Faculty of Science, Department of Information and Computer Sciences
  • Utrecht University – University Medical Centre Utrecht;
  • National Institute for Public Health and the Environment (RIVM), Centre for Infectious Disease Control (CIb);
  • Animal Health Service;
  • Vion Food Group;
  • Product Boards for Livestock, Meat and Eggs