Is your pet making you sick?

PROFESSOR NIGEL FRENCH - Director, Infectious Disease Research Centre

Basic hygiene around household pets could avoid the spread of multi-drug-resistant bacteria.

New Zealanders have a strong affection for household pets—studies show that 68% of households own at least one animal companion. But these animals are also a possible source of multi-drug-resistant bacterial infections, which the World Health Organization has identified as a major threat to human health, with numbers of infections on the rise.

There has also been an increase in infections from these bacteria in companion animals around the world, including New Zealand, plus there has been evidence of these antibiotic-resistant bacteria passing between people and animals, and vice versa, and the rates of infection in the community setting—that is, outside of hospitals and other institutions—have increased.

Public health specialists and clinical micro-biologists, in collaboration with veterinary researchers from Massey’s Molecular Epidemiology and Public Health Laboratory (mEpiLab), are conducting a study that aims to identify novel risk factors for the growing number of community-acquired infections in New Zealand. Massey researchers are working in collaboration with the Institute of Environmental Science and Research (ESR), Labtests Auckland and the University of Otago.

The researchers aim to investigate possible links between companion animals carrying resistant bacteria and human infection.

It underlines what most people already know—you shouldn’t let your dog lick your face.


Reducing transmission

“Strains of the resistant bugs are spread through communities. We want to understand the dynamics of a small community, a family, to ultimately inform public interventions to reduce transmission,” says Massey’s Dr Jackie Benschop, an epidemiologist with extensive field experience in clinical veterinary practice who is one of the lead investigators on the project.

The study investigates the members of the Enterobacteriaceae family that produce extended-spectrum beta-lactamases (ESBL-E) and plasmid-mediated AmpC beta-lactamases (PMACBL-E). These bacteria show resistance to the majority of beta-lactam drugs, such as penicillins, and other important classes of antibiotics.

The project also aims to assess risk factors for community bacterial infections which are not linked to healthcare facilities or residential homes, and to assess the population genetics, diversity and transmission of ESBL/PMACBL-E bacteria in humans and companion animals. The project begins with a case-control study of 175 cases of community-acquired ESBL/PMACBL-E infections and 525 randomly selected controls.

The study looks at how households interact with their pets, and how antibiotic use and lifestyle factors may contribute to the spread of drug-resistant bacteria between animals and humans. Researchers will carry out an assessment of the molecular epidemiology, virulence profile, transmissibility, population structure and phylodynamics of ESBL/PMACBL-E isolated from humans and household pets, using faecal samples from both human and animal subjects. Finally, a mathematical model will be created for evaluating generally considered interventions informed by data and information from the case study.

Lead researcher Professor Nigel French, Director of the Infectious Disease Research Centre and Executive Director of the Molecular Epidemiology and Public Health Laboratory in the Hopkirk Research Institute at Massey’s Palmerston North campus, says the resistant infections have been found in most household pets. The bacteria are spread in fluids and faeces, and as “animals clean their backside by licking it, they can get faecal contamination in their mouth and then lick humans. That’s how the infection could be transmitted.

“It underlines what most people already know—you shouldn’t let your dog lick your face. If the dog licks your hands, you should wash your hands afterwards. It’s basically hand hygiene and avoiding too intimate contact with your pet,” Professor French says.

The research project, which is being assisted by doctoral student Leah Toombs-Ruane, will provide new evidence of the risk factors for ESBL/PMACBL-E infections in humans in New Zealand. It will also contribute to collective knowledge that can be practically applied to effectively minimise potential risks of carrying resistant bacteria as well as other similar infections.

And while investigating these potential risks, the researchers noted that it isn’t something to get overly concerned about. “One of our key messages is that the benefits of pet ownership, in terms of social and physical health, far outweigh the risks,” Dr Benschop says.

Project details

Funders Health Research Council
Dates 2014 to 2017