In a statement, the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) said that the research will be presented at its Global Congress in Barcelona (Spain) from 27 to 30 April. Having found "evidence of transmission of multidrug-resistant bacteria between diseased dogs and cats and their healthy owners in Portugal and the United Kingdom", the study raises concerns "that companion animals may act as reservoirs of resistance and thus contribute to the spread of resistance to essential medicines".

In this sense, it draws attention to the importance of including families with pets in antibiotic resistance surveillance programmes, the statement said.

The World Health Organization (WHO) classifies antibiotic resistance as one of the greatest threats to public health facing humanity.

Drug-resistant infections kill more than 1.2 million people worldwide each year and are expected to kill 10 million by 2050 if no action is taken.

"Recent studies indicate that transmission of antimicrobial resistance (AMR) bacteria between humans and animals, including companion animals, is crucial in maintaining resistance levels, challenging the traditional belief that humans are the main carriers of AMR bacteria in the community," says Juliana Menezes, a PhD student at the Antibiotic Resistance Laboratory of the Interdisciplinary Centre for Animal Health Research at the Faculty of Veterinary Medicine of the University of Lisbon, who is working on the project led by Constança Pomba.

"Analysing and understanding the transmission of AMR bacteria from pets to humans is essential to effectively combat antimicrobial resistance" in humans and animals, adds the PhD student.

The study involved five cats, 38 dogs and 78 people in 43 homes in Portugal and 22 dogs and 56 people in 22 homes in the United Kingdom. All humans were healthy and all pets had skin and soft tissue infections or urinary tract infections.

The scientists tested stool and urine samples and skin swabs from the animals and their owners for Enterobacterales (a family of bacteria that includes Escherichia coli and Klebsiella pneumoniae) resistant to common antibiotics.

The focus was on bacteria resistant "to third-generation cephalosporins" (one of the most important antibiotics, according to the WHO) and "to carbapenems (part of the last line of defence when other antibiotics fail)".

According to the statement, "it was not possible to prove the direction of transmission", but "in three of the Portuguese households, the timing of the positive tests for ESBL/AmpC-producing bacteria strongly suggests that, at least in these cases, the bacteria had passed from the pet to the human".

Juliana Menezes believes that "learning more about resistance in pets would help in the development of evidence-based and targeted interventions to protect animal and human health".

Caresses, touches or kisses and touching the animal's faeces allow the bacteria to pass between dogs and cats and their owners, so the researchers ask for attention to hand washing after petting animals or handling their waste.

"When your pet is unwell, consider isolating it in one room to avoid the spread of bacteria around the house and clean the rest of the house thoroughly," advises the researcher.

All dogs and cats were infection-free after treatment.

Read Also: More than 40,500 mosquitoes detected, none with dengue or Nile fever (Portuguese version)