Selection of Antibiotic Resistance in Domestic and Farmed Animals and Implications for Transmission to Humans

Without antimicrobial drugs, the risk of bacterial infection would render many common medical procedures too dangerous to contemplate because of the risk of infections caused by "opportunistic bacteria". They can live on the patient's skin, or in their intestines, and infection occurs when bacteria get into parts of the body that are normally sterile. A perfect example is urinary tract infection (UTI) caused by faecal bacteria. E. coli is particularly abundant in human faeces so is perfectly placed to cause opportunistic infections. It is one of the most common causes of healthcare pneumonia, surgical site infection, bloodstream infection and UTI in the UK. In order to prevent against and treat opportunistic infections, patients are given antimicrobials.

In this project we will identify what drives acquisition of AMR in animals using E. coli as the exemplar bacterium and dairy cows and dogs as exemplar farmed and companion animals. We will test whether AMR bacteria encountered by an animal as it interacts with the environment influence the AMR profile in its faeces, and/or whether early life antimicrobial use plays a part in selection of AMR bacteria in animals. We will also test whether reducing antimicrobial use in dairy cows actually does reduce AMR in the near-farm environment that is contaminated with their faeces. We will test whether exercising in these contaminated near-farm environments influences the abundance of AMR bacteria in dogs, and whether there is any evidence of direct acquisition of AMR E. coli by dogs from near-farm environments, which might be brought into the home.

Finally, we will investigate whether AMR abundance in human UTI E. coli reduces as antimicrobial drug prescribing reduces in primary care; whether living close to a farm affects AMR abundance in UTI E. coli; whether there is direct evidence for E. coli carried by dogs or found in near-farm environments contaminated by cattle faeces also causing UTIs in humans.

These interlaced studies will provide much needed data about the management changes that might reduce AMR in animals and in humans, and are designed to address the fundamental question of whether zoonotic transmission is particularly significant as a driver of AMR in people relative to antimicrobial drug use by doctors.