Multi-drug resistant organisms can be transmitted between healthy dogs and cats and their hospitalized owners


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Healthy dogs and cats could transmit multi-drug resistant organisms (MDRO; bacteria that are resistant to treatment with more than one antibiotic) to their hospitalized owners, and similarly humans could transmit these dangerous microbes to their pets , according to new research presented at this year’s European Congress of Clinical Microbiology and Infectious Diseases (ECCMID) in Copenhagen, Denmark (April 15-18).

The study of more than 2,800 hospitalized patients and their pets is carried out by Dr. Carolin Hackmann of Charité University Hospital in Berlin, Germany, and her colleagues.

“Our results confirm that the sharing of multidrug-resistant organisms between pets and their owners is possible,” says Dr. Hackmann. “However, we have identified only a handful of cases suggesting that neither cat nor dog ownership is a significant risk factor for colonization of multidrug-resistant organisms in hospitalized patients.”

The role of companion animals as potential reservoirs of MDRO is of growing concern worldwide. Antimicrobial resistance occurs when microbes that cause infections (such as bacteria, viruses or fungi) evolve to become resistant to the drug designed to kill them. Estimates suggest that antimicrobial resistant infections caused nearly 1.3 million deaths and were associated with nearly 5 million deaths worldwide in 2019.

In this case-control study, the researchers wanted to know if companion animals (i.e. cats and dogs) played a role in infecting hospitalized patients with MDRO.

They focused on the most common superbugs in hospitalized patients – methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), 3rd generation cephalosporin-resistant Enterobacteriaceae (3GCRE) and resistant Enterobacteriaceae. to carbapenems (CRE), which are resistant to several antibiotics including penicillin and cephalosporins.

Between June 2019 and September 2022, nasal and rectal swabs were taken from 2,891 hospitalized patients at the Charité University Hospital in Berlin (1,184 patients who had already been colonized or colonized on admission and 1,707 newly admitted patients as witnesses), and on all the dogs and cats that lived in their households.

Genetic sequencing was used to identify both the species of bacteria in each sample and the presence of drug resistance genes. Whole genome sequencing was used to confirm the possible sharing of resistant bacteria.

Participants were also asked about well-known risk factors for MDRO (e.g., recent MDRO infections or use of antibiotics, recent hospital stays, presence of urinary or central venous catheters) , as well as information on the number of pets in the household, the proximity of contacts and the health of the animals.

Overall, 30% (871/2891) of hospitalized patients tested positive for MDRO and 70% (2020/2891) tested negative. The dog ownership rate was 11% (93/871) and 9% (80/871) among MDRO-positive people, and 13% (267/2,020 and 253/2,020 respectively) among MDRO-negative.


All 626 pet owners were asked to send throat and stool samples from their pets. A total of 300 animal owners returned samples from 400 animals. Of these samples, 15% (30/203) of dogs and 5% (9/197) of cats tested positive for at least one MDRO. In four cases, the MDROs matched phenotypically (the MDROs belonged to the same species and showed the same resistance to antibiotics) between the pets and their owners.

Whole genome sequencing confirmed that only one of the matched pairs was genetically identical in a dog and its owner. The corresponding pathogen was 3GCR Escherichia coli (common in the intestines of healthy people and animals).

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

This is an observational study and cannot prove that close contact with pets causes MDRO colonization, but only suggests the possibility of co-carriage, whereas the direction of transfer n is not clear. The authors point out several limitations, including possible under-reporting of MDRO colonization in pets due to issues with swab sample collection, which was done by pet owners themselves. Finally, the results of the study apply to the inpatient setting in an urban area and therefore may not be applicable to the general population or MDRO high-risk groups such as pastoralists.

Provided by the European Society for Clinical Microbiology and Infectious Diseases

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