Healthy pet dogs and cats could be transmitting both antibiotic-resistant bacteria and genes involved in bacterial resistance to their owners, according to new research from the UK and Portugal.
The preprint, but peer reviewed, study findings, to be presented at this year’s European Congress of Clinical Microbiology & Infectious Diseases in Lisbon, Portugal, later this month, "highlight the importance of contact between healthy companion animals and humans to the spread of resistant bugs that may lead to potentially untreatable infections in the community", said the authors.
The role of companion animals as potential reservoirs of antimicrobial-resistant bacteria is a growing concern worldwide. The researchers wanted to find out how these resistant bacteria are spread, and whether there is a cross-over between healthy cats and dogs and their owners.
They recruited owners and pets from those attending the Small Animal Veterinary Teaching Hospital at the University of Lisbon and the Royal Veterinary College Small Animal Veterinary Referral Service at the Royal Veterinary College in Hatfield in the UK between 2018 and 2020. Only animals and their owners who had not experienced bacterial infections or taken antibiotics in the 3 months prior to the start of the study were enrolled.
Stool samples were collected from both people and pets at monthly intervals for 4 months, and genetic sequencing was used to identify the species of bacteria in each sample, as well as the presence of drug resistance genes. Samples were tested with Rep-PCR, a molecular fingerprinting technique that helps to identify related strains of bacteria. The researchers also sequenced the strains to confirm possible sharing of resistant bacteria.
In the UK, samples were provided from 56 healthy people living in 42 households, along with their 45 dogs. In Portugal, stool samples were collected from 58 healthy people in 41 households, and from the 18 cats and 40 dogs that lived with them. The health of companion animals was evaluated by their vet when attending the clinics.
Of the 103 pets in the study, 15 (15%; 1 cat and 14 dogs) were found to be carrying ESBL/AmpC-producing Enterobacteriaceae, which are known to be resistant to multiple antibiotics including penicillin and cephalosporins. These were also found in 15 (13%) of the 114 household members from both countries. Of the total, almost half the cats and dogs (6 in Portugal and 1 in the UK), and a third of the household members (4 in Portugal and 1 in the UK), were colonised with at least one multidrug-resistant strain
In four Portuguese households, the ESBL/pAMPc resistance genes found in pets matched those found in their owner’s stool samples, although in three of these households matched resistance genes were only recovered at one timepoint. However, in one household, sharing strains were noted at two consecutive timepoints, suggesting a persistent colonisation of shared bacteria.
In addition, in two of the households, the microbes in pets matched Escherichia coli (E. coli) strains found in their owner’s stool sample.
Study Gives 'Snapshot Insight' to Pathogens Shared
Co-author Dr Sian Frosini, lecturer in Veterinary Clinical Microbiology at the Royal Veterinary College told Medscape UK: "This study gives a snapshot insight into the presence of some multidrug-resistant (MDR) pathogens within healthy pet-owning households. It is interesting to see sharing of both identical bacterial isolates and resistance genes in certain case; however no conclusions can be made about which direction transmission is occurring in. These pathogens have also been described previously in the environment (both inside and outside)."
She added: "As with any infection where there is a risk of contagion, rigorous hygiene measures such as handwashing and avoiding contact with faecal or infected material is paramount in all households, including those with pets. Although pets may contribute to spread of MDR pathogens, in the same way a contaminated door handle might, the benefits of pet ownership on human health should not be overlooked."
The British Veterinary Association (BVA) has for some years pressed for responsible antibiotic use to mitigate resistance, and has joined the 'One Heath' initiative for shared policies between human and veterinary medicines in a joint campaign supported by the British Medical Association and Public Health England.
Malcolm Morley, junior vice president of the BVA, told Medscape UK: "This abstract adds valuable insights into the evidence base for the close links between human and animal health, specifically the transmission of antibiotic-resistant bacteria and genes between human and animal populations. However, what's covered in the abstract doesn’t confirm or specify the direction of transmission of these bacteria, which is why it is important that pet owners don’t unnecessarily worry about close contact with healthy dogs and cats as a result.
"Antimicrobial resistance remains a huge concern for the veterinary profession, with 9 in 10 UK vets surveyed last year reporting that they are worried about their ability to treat infections in pets. Vets in the UK have taken the lead in promoting the responsible use of antimicrobials in companion animals as well as livestock, with the overall aim of promoting responsible prescribing and use across both sectors, in the wider context of One Health.
"Our advice for pet owners remains to use antibiotics responsibly and to follow their vet’s instructions in giving the recommended dose at the right time and for the duration prescribed. We’d also always advise animal owners to practise good hygiene if either they or their pet are unwell, including regular handwashing before and after handling if their pet requires care."
The paper abstract will be presented at the European Congress of Clinical Microbiology & Infectious Diseases being held in Lisbon on April 23-26. All accepted abstracts have been extensively peer reviewed by the congress selection committee. The full paper is not yet available, and has not yet been submitted for publication.
The work was supported by JPIAMR/0002/2016 Project—PET-Risk Consortium and by FCT – Fundação para a Ciência e Tecnologia IP (UIDB/00276/2020); JM and JMS were supported by a PhD fellowship.
The authors declare no conflicts of interest.
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