Antibiotic-resistant “superbugs” – identified by the World Health Organization as one of the greatest global public health threats – typically conjure up images of hospital environments. However, research may point to a less obvious source: the family dog.
Researchers warned of “an international public health risk” after finding antibiotic-resistant bacteria in a number of different types of raw dog foods.
“The trend to feed dogs raw food could encourage the spread of antibiotic-resistant bacteria,” said the researchers in a press release on their study, which will be presented at the European Congress on Clinical Microbiology and Infectious Diseases.
A separate study presented at the same conference found that resistance to a last resort antibiotic could be transmitted between domestic dogs and their owners.
Antibiotic-resistant bugs can make minor injuries and frequent infections potentially fatal.
Resistance has increased in recent years due to the overuse of such drugs in humans and farm animals.
In the dog food study, a team from the University of Porto analyzed 55 dog food samples from 25 brands – including 14 raw frozen varieties – for enterococcal bacteria.
The bacteria can live harmlessly in the human and animal intestines, but they can also be dangerous and resistant to antibiotics in other parts of the body.
The researchers found that all raw dog food samples contained antibiotic-resistant enterococci, including bacteria resistant to the final antibiotic, linezolid.
Genetic sequencing found that some of these antibiotic-resistant bacteria in raw dog food were of the same type found in hospital patients in the UK, Germany and the Netherlands.
“The close contact between humans and dogs and the commercialization of the brands examined in different countries pose an international risk to public health,” said researcher Ana Freitas.
“The European authorities need to raise awareness of the potential health risks involved in feeding raw food to pets, and the production of dog food, including the choice of ingredients and hygiene practices, needs to be reviewed.”
She added that dog owners should wash their hands after handling pet food and disposing of feces.
In a separate study, which has not yet been submitted to a medical journal for publication, another team from Portugal tested pet owners and animals from 80 households for bacteria with the MCR-1 gene, which confers resistance to the last resort antibiotic colistin.
All 126 people were healthy, while half of the 102 pets examined had either skin or urinary tract infections.
Four people and eight dogs tested positive for bacteria carrying MCR-1, and the gene was found in both the dog and its owner in two households.
“Genetic analysis of the samples indicated that in either of these two cases the gene was transferred between the pet and the owner,” he said.
This raised concerns that pets could spread resistance to the last resort antibiotic.
The WHO classifies antibiotic resistance as one of the greatest threats to public health.
An estimated 700,000 people die from drug-resistant infections worldwide each year, and the United Nations has warned that if no action is taken, they could rise to 10 million by 2050.