Perhaps one of the most alarming findings in the recently-concluded European Congress of Clinical Microbiology & Infectious Diseases (ECCMID) is that raw dog food contains significant amounts of antibiotic-resistant bacteria, making them a public health risk to Europe and the rest of the world.

The new study, led by researchers from the University of Port in Portugal, additionally reveals that some of the antibiotic-resistant bacteria from industrial dog food are similar to those that are found in hospitals.  This makes feeding dogs the new vehicle for transmitting diseases brought about by these superbugs. Researchers presented their study in the report "Industrial dog food is a vehicle of multidrug-resistant enterococci carrying virulence genes often linked to human infections," published in the International Journal of Food Microbiology.

Novosibirsk Domestic and Stray Animal Centre
(Photo : Photo by Kirill Kukhmar\TASS via Getty Images)
NOVOSIBIRSK, RUSSIA - MARCH 17, 2021: A woman brings food for dogs kept in a shelter at the Novosibirsk Domestic and Stray Animal Centre.

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Rising Health Risk from Antibiotic-Resistant Bacteria

According to the Centers for Disease Control and Prevention (CDC), antibiotic-resistant bacteria is now one of the "biggest public health challenges of our time," citing that in the US alone, at least 2.8 million people get infected with it and more than 35,000 people die each year. The WHO adds that it kills about 70,000 people globally and is expected to grow to as much as 10 million by the year 2050 if no significant steps are taken against antibiotic-resistant bacteria.

The CDC explains that antibiotic-resistant bacteria emerge when common strains develop the ability to fight off the drugs intended to eliminate them. When a population is exposed to an antibiotic, the surviving part continues to grow and start developing resistance to the particular medicine.

To find out whether pet food actually carries these superbugs, Dr. Ana R. Freitas, Dr. Carla Novais, Dr. Luísa Peixe — together with their colleagues from the UCIBIO, Faculty of Pharmacy, University of Porto, Portugal - analyzed samples from commercially available dog foods, checking them for Enterococci. These are "opportunistic" bacteria that are usually found among the guts of both humans and animals. However, enterococci can cause severe diseases when spread to other parts of the body.

The samples include 55 different dog food specimens: 22 wet, 4 semi-wet, 8 dry, 7 treats, and 14 raw-frozen samples. Raw frozen foods included materials from duck, turkey, chicken, salmon, lamb, goose, beef, and vegetables. These are distributed among 25 brands that were available in supermarkets and pet shops internationally.

Finding Superbugs, Both in Patients and in Dog Food

An analysis of the samples showed that thirty samples out of 55 contained Enterococci, with about 40 percent of this sample being resistant to different antibiotics — erythromycin, quinupristin-dalfopristin, streptomycin, tetracycline, gentamicin, ampicillin, ciprofloxacin, or chloramphenicol. Other samples exhibited resistance to teicoplanin and vancomycin, with about a quarter (23 percent) being resistant to linezolid. Linezolid, in particular, is a last-resort antibiotic used when others have failed - a critically important treatment recognized by the WHO.

After conducting genetic sequencing of the superbugs found in the dog food, it was proven to be similar to those found in samples isolated from hospital patients in Europe. It led researchers to conclude that dog food is a source of antibiotic-resistant bacteria, and could have been an overlooked factor in the increase of antibiotic resistance around the world.

 

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