Antibiotic-resistant ‘superbugs’ are being passed between dogs and cats and their owners

[Apr. 16, 2023: JD Shavit, The Brighter Side of News]

Antibiotic resistance is becoming increasingly prevalent worldwide, with drug-resistant infections estimated to kill around 700,000 people annually. The World Health Organisation (WHO) has classified antibiotic resistance as one of the most significant public health threats facing humanity, with the number of projected deaths estimated to rise to 10 million by 2050 if no action is taken.

The overuse and misuse of antibiotics in both human and veterinary medicine are major contributors to the development and spread of antibiotic-resistant bacteria.

In response to the threat, the WHO has launched a global campaign to promote the responsible use of antibiotics in both human and animal medicine. The campaign aims to raise awareness of the risks of antibiotic resistance, promote the appropriate use of antibiotics, and encourage the development of new antibiotics and alternative treatments.

According to a new study presented at the European Congress of Clinical Microbiology & Infectious Diseases (ECCMID), multidrug-resistant bacteria are being transmitted between pets and their owners. The study shows that dogs and cats carrying antibiotic-resistant bacteria are sharing them with their owners, highlighting the importance of including pet-owning households in programs to reduce the spread of antimicrobial resistance.

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Pets, including dogs and cats, are known to contribute to the spread of antibiotic-resistant pathogens that can cause human disease. The study, conducted by Juliana Menezes and colleagues from the Antibiotic Resistance Lab at the Centre of Interdisciplinary Research in Animal Health, Faculty of Veterinary Medicine, University of Lisbon, Portugal, aimed to find out whether pets treated with antibiotics for infections are sharing such pathogens with their owners.

The researchers tested faecal samples from dogs and cats and their owners for Enterobacterales, a family of bacteria that includes E. coli and Klebsiella pneumoniae that are resistant to common antibiotics. They focused on bacteria resistant to third-generation cephalosporins, which are used to treat a broad range of conditions, including meningitis, pneumonia, and sepsis.

These antibiotics are classified among the most critically important antibiotics for human medicine by the WHO, as well as carbapenems, which are part of the last line of defense when other antibiotics have failed.

The longitudinal study involved 5 cats, 38 dogs, and 78 humans from 43 households in Portugal and 7 dogs and 8 humans from 7 households in the UK. In Portugal, one dog (1/43 pets, 2.3%) was colonized by a strain of multidrug-resistant OXA-181-producing Escherichia coli. OXA-181 is an enzyme that confers resistance to carbapenems. Three cats and 21 dogs (24/43 pets, 55.8%) and 28 owners (28/78, 35.9%) harbored ESBL/Amp-C producing Enterobacterales. These are resistant to third-generation cephalosporins.

In eight households, two houses with cats and six with dogs, both pets and owners were carrying ESBL/AmpC-producing bacteria. In six of these homes, the DNA of the bacteria isolated from the pets (one cat and five dogs) and their owners was similar, meaning these bacteria were probably passed between the animals and humans. It is not known whether they were transferred from pet to human or vice versa.

In the UK, one dog (1/7,14.3%) was colonized by multidrug-resistant E. coli producing NDM-5 and CTX-M-15 beta-lactamases. These E. coli are resistant to third-generation cephalosporins, carbapenems, and several other families of antibiotics. ESBL/AmpC-producing Enterobacterales were isolated from five dogs (5/7, 71.4%) and three owners (3/8, 37.5%).

In two households with dogs, both pets and owners were carrying ESBL/AmpC-producing bacteria. In one of these homes, the DNA of the bacteria isolated from the dog and owner was similar, suggesting that the bacteria probably passed from one to the other. The direction of transfer is unclear.

All of the pets in the study were successfully treated for their infections. However, the findings of this study suggest that pet animals can be a potential source of multidrug-resistant bacteria that can spread to humans.

The study's authors warn that the overuse of antibiotics in veterinary medicine may contribute to the development of drug-resistant bacteria in pets. Antibiotics are often prescribed to treat bacterial infections in pets, but they may not be necessary or effective in some cases. The researchers emphasize the importance of using antibiotics judiciously in veterinary medicine to prevent the development of antibiotic-resistant bacteria in pets.

The findings also highlight the need to include pet-owning households in programs to reduce the spread of antimicrobial resistance. The researchers suggest that pet owners should practice good hygiene, including washing their hands after handling their pets, especially after cleaning up their pets' waste, and even after petting them. Pet owners should also ensure that their pets receive appropriate veterinary care and follow their veterinarian's instructions for administering antibiotics.

The European Congress of Clinical Microbiology & Infectious Diseases (ECCMID) is an annual event that brings together leading experts in the field of infectious diseases. The conference provides a platform for researchers and clinicians to present their latest findings and discuss strategies for preventing and treating infectious diseases.

The findings of this study are significant because they suggest that pet animals can be a potential source of multidrug-resistant bacteria that can spread to humans. The study's authors call for further research to investigate the extent of the problem and to develop strategies for preventing the spread of antibiotic-resistant bacteria from pets to humans.

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