Study Finds Pets Not a Substantial Reservoir for Human Multidrug-Resistant Infections

An abstract due to be presented at the 2020 European Congress of Clinical Microbiology and Infectious Diseases (ECCMID) genetically matched multidrug-resistant organisms (MDRO) in humans and their pets, suggesting zoonotic transfer of MDROs is possible in this context. But importantly, only a small number of cases were found, suggesting this is not a major source of resistant infections in humans.

“So far, the preliminary data does not indicate pet husbandry as a significant factor for MDRO colonization in hospital patients,” the abstract authors wrote.

In light of the coronavirus disease 2019 pandemic, ECCMID was cancelled. However, a book containing the abstracts that would have been presented has been released by conference organisers.

The study was motivated by a broader need to understand the role of pet care in the infection of hospital patients with MDROs, since the potential for mediation has been unclear.

The study focused on the MDROs most commonly found among pet owners: methicillin-resistant Staphylococcus aureus (MRSA), third-generation cephalosporin-resistant Enterobacterales, vancomycin-resistant enterococci (VRE), and carbapenem-resistant Enterobacterales (CRE).

The authors of the study assessed risk factors for colonization by asking pet owners questions related to their contact with dogs and cats. Information such as the number of pets in the home, closeness of contact, and medical history of pets were established.

Genetic analysis was performed on nasal and rectal swabs in order to determine the relationship between human and pet MDROs. When MDROs in the samples collected were a phenotypic match, they were tested for a genetic relationship via whole genome sequencing.

Among an initial 1500 participants, 495 (33%) tested positive for MDROs.

In total, 296 participants (20%) owned at least 1 pet, and 38% of these owners (112) tested positive for MDROs. This did not establish a significant difference in the proportion of pet owners between cases and controls.

Secondary analysis of information gathered from owners such as closeness of contact or pet health also revealed no significant differences between cases and controls.

Among samples of 77 dogs and 71 cats from 112 pet owners, 14% of pets (23 dogs and 1 cat) tested positive for 1 MDRO each. In 2 cases, MDROs were phenotypically matching between a dog and its owner.

The matching pathogens were VR Enterococcus faecium and third-generation cephalosporin-resistant Escherichia coli. Whole genome sequencing confirmed the relation between the organisms.

“This analysis of preliminary data showed no significant difference in pet care or closeness of contact to pets between MDRO-positive and MDRO-negative hospital patients. A transmission of MDROs between human and animal was confirmed in only 1.8% of 112 pet owners and their respective pets. So far, the preliminary data does not indicate pet care as a significant risk factor for MDRO colonisation in hospital patients,” the abstract authors concluded.

The abstract, “The transmission risk of multidrug-resistant organisms between pets and humans: an exploratory case control study protocol,” was published in a collection of abstracts which were due to be presented at ECCMID2020.