Public health risk from multidrug-resistant bacteria in dog food
European Society of
Clinical Microbiology and Infectious Diseases
Research presented by
Dr Ana R. Freitas, and colleagues from UCIBIO, Faculty of Pharmacy, University
of Porto, Portugal, showed that dog food from supermarkets and pet shops was a
major source of antibiotic-resistant bacteria, making it an international
public health risk.
With some of the
multidrug-resistant bacteria in raw dog food identical to those found in
hospital patients in several different European countries, the researchers say
the trend for feeding dogs raw food may be fuelling the spread of antibiotic
resistant-bacteria.
Drug-resistant
infections kill an estimated 700,000 people a year globally and, with the
figure projected to rise to 10 million by 2050 if no action is taken, the World
Health Organisation (WHO) classes antibiotic resistance as one of the greatest
public health threats facing humanity.
A total of 55
samples of dog food (22 wet, 8 dry, 4 semi-wet, 7 treats and 14 raw-frozen)
from 25 brands available nationally and internationally were included in the
study. The raw-frozen foods included duck, salmon, turkey, chicken, lamb,
goose, beef and vegetables.
Thirty samples
(54%) contained Enterococci. More than 40% of the Enterococci were resistant to
the antibiotics erythromycin, tetracycline, quinupristin-dalfopristin,
streptomycin, gentamicin, chloramphenicol, ampicillin or ciprofloxacin. There
was also resistance to vancomycin and teicoplanin (2% each) and 23% of the
enterococci were resistant to linezolid, a last-resort antibiotic. All of the
raw dog food samples contained multidrug-resistant Enterococci, including
bacteria resistant to linezolid. In contrast, only three of the non-raw samples
contained multidrug- resistant bacteria.
Genetic sequencing
revealed that some of the multi-drug resistant bacteria in the raw dog food
were identical to bacteria isolated from hospital patients in the UK, Germany
and the Netherlands. Genetically identical bacteria have also been found in
farm animals and wastewater in the UK.
The researchers
concluded that dog food is a source of bacteria that are resistant to
last-resort antibiotics and could potentially spread to humans. Dog food, they
add, could be an overlooked driver of antibiotic resistance globally.
Dr Freitas said:
“The close contact of humans with dogs and the commercialisation of the
studied brands in different countries poses an international public health
risk. European authorities must raise
awareness about the potential health risks when feeding raw diets to pets and
the manufacture of dog food, including ingredient selection and hygiene
practices, must be reviewed. Dog owners should always wash their hands with
soap and water right after handling pet food and after picking up faeces.”