Healthy pets can transmit dangerous microbes to humans and vice versa- study

Healthy pets could be passing on multidrug-resistant organisms (MDROs; bacteria that resist treatment with multiple antibiotics) to their hospitalized owners, and furthermore, humans could be transferring these dangerous microbes to their dogs and cats, according to new research published in the peer-reviewed journal The Lancet. 

What is antimicrobial resistance?

Antimicrobial resistant infections caused an estimated 1.3 million deaths and were associated with nearly 5 million deaths around the world in 2019. The resistance occurs when infection-causing microbes (such as bacteria, viruses or fungi) evolve to become resistant to the drug designed to defeat them. 

Curious whether cats and dogs play a role in the infection of hospital patients with multidrug-resistant organisms, researchers examined over 2,800 hospital patients and their furry friends. 

The team used genetic sequencing to identify both the species of bacteria and the presence of drug resistance genes in all provided samples. Whole genome sequencing was used to confirm the possible sharing of resistant bacteria.

Participants were also asked about well-known risk factors for MDROs such as a recent MDRO infections or use of antibiotics, recent hospital stays, presence of urinary or central venous catheters), as well as information about the number of pets in the household, the closeness of contact and pet health.

Overall, 30% of hospital patients tested positive for MDROs. In those patients, 11% owned a dog and 9% owned a cat. 

All 626 pet owners were instructed to provide throat and stool swab samples of their animal companions. Swabs were taken by the owners themselves, a possible study limitation, researchers noted. Overall, 300 pet owners sent back samples from 400 pets. Of these samples, 15% of dogs and 5%  of cats tested positive for at least one MDRO.

Researchers noted that the observational study only applies to patients in an urban area and therefore may not be applicable to the general population or MDRO high risk groups such as livestock farmers.

"Our findings verify that the sharing of multidrug-resistant organisms between companion animals and their owners is possible," said Carolin Hackmann from Charite University Hospital Berlin, Germany.

"However, we identified only a handful of cases suggesting that neither cat nor dog ownership is an important risk factor for multidrug-resistant organism colonisation in hospital patients," he added.

“Although the level of sharing between hospital patients and their pets in our study is very low, carriers can shed bacteria into their environment for months, and they can be a source of infection for other more vulnerable people in hospital such as those with a weak immune system and the very young or old,” Hackmann continued.