Study links pet and human antibiotic-resistant Klebsiella strains

Dogs and cats are carrying some of the same antibiotic-resistant Klebsiella pneumoniae lineages found in people, according to new research that pushes companion animals further into the center of the One Health AMR conversation. In the Bournemouth University-led study, published in Transboundary and Emerging Diseases, investigators compared 712 animal isolates from 25 countries with more than 38,000 human genomes and found extensive overlap in strain types, with 87.2% of companion-animal isolates belonging to sequence types also seen in humans. (eprints.bournemouth.ac.uk)

What makes the paper notable is its scale. Earlier work had linked resistant bacteria in pets and people within households, clinics, or single-country datasets, but Bournemouth said this is the first large-scale global map of the genetic structure of K. pneumoniae in domestic dogs and cats. The study found that 71.1% of companion-animal sequence types overlapped with those identified in humans, suggesting pets are participating in the same broader bacterial ecology, even if the study does not prove direct pet-to-person transmission. (eprints.bournemouth.ac.uk)

The resistance signal was also hard to ignore. Nearly half of the animal-derived isolates carried genes linked to resistance to clinically important antibiotics, and multidrug resistance was more common in cat-derived isolates than dog-derived isolates, 80.0% versus 56.3%. The paper highlighted ST147 as a particular concern: a cat-enriched multidrug-resistant cluster that also included dog-derived and closely related human comparator genomes, indicating this was not an animal-restricted lineage. (eprints.bournemouth.ac.uk)

That finding fits with a wider body of veterinary AMR research. In a separate 2026 Frontiers study of oral and oropharyngeal Enterobacterales carriage in people and companion animals seen through Mississippi State University’s veterinary setting, dogs had much higher carriage prevalence than humans or cats, and recent antibiotic administration and recent hospitalization were associated with increased odds of canine Klebsiella carriage. Whole-genome sequencing in that study also identified clinically important resistance determinants, including CTX-M-15 and NDM-5, in human and dog isolates. (frontiersin.org)

Researchers and sector groups are increasingly framing companion animals as an undercounted part of the AMR picture. The Bournemouth team said there is “no need” for pet parents to be alarmed, because shared genetic background alone doesn’t establish transmission, but lead author Stephen Fordham said the work shows why pets should be included in wider efforts to understand and tackle AMR. Separately, the World Organisation for Animal Health said earlier this year that AMR in companion animals is increasingly recognized as a threat to both animal and public health, while noting that surveillance in pets still lags behind that in humans and food animals. (bournemouth.ac.uk)

Why it matters: For veterinary professionals, this is less a call for alarm than a call for integration. Resistant Klebsiella and other Enterobacterales are no longer just a referral-hospital or human-health story. The practical implications touch prescribing decisions, culture and susceptibility testing, infection prevention in clinics, and discussions with pet parents after repeated antibiotic exposure or recent hospitalization. A recent systematic review found antimicrobial use, raw feeding, and hospitalization were the most consistent risk factors for AMR-Enterobacterales carriage in dogs, reinforcing the same stewardship and biosecurity themes emerging from the new studies. (frontiersin.org)

The bigger takeaway is that veterinary medicine may need better routine visibility into which lineages are circulating, not just whether an isolate is resistant. High-risk human-associated clones appearing in pets could influence empiric treatment success, outbreak recognition, and referral-hospital protocols over time. And because carbapenem-resistant Enterobacterales have been detected in companion animals despite carbapenems not being approved for routine veterinary use in most settings, some experts argue these strains are often introduced from human-associated ecosystems and then maintained or spread within animal or clinical networks. (woah.org)

What to watch: The next step is whether these genomic findings translate into broader surveillance programs, clearer veterinary stewardship guidance, and more studies that can distinguish shared reservoirs from actual transmission events between pets, people, and clinics. (woah.org)