Researchers suggest that maintaining good hygiene can help reduce the risk of infections.
Antibiotic-resistant salmonella poses a growing threat to public health because the bacteria have evolved to resist antibiotic treatments. According to the U.S. Centers for Disease Control and Prevention (CDC), people can contract Salmonella by consuming contaminated food or through contact with infected people or animals, often through accidental exposure to feces via hand-to-mouth contact or while petting animals.
However, Penn State researchers have identified domestic dogs as an underestimated source of zoonotic pathogens, including non-typhoid salmonella. This strain can cause symptoms such as diarrhea, fever, and abdominal cramps, with some cases leading to serious, life-threatening complications.
Published in the journal Zoonoses and public healthThe study highlights how close human-dog interactions and the use of essential antibiotics in veterinary care increase the risk of spreading antimicrobial-resistant Salmonella. The researchers point out that greater awareness and good hygiene practices could help reduce the risk of cross-species transmission.
Salmonella infections in dogs can be clinical – showing signs or symptoms – or asymptomatic, with many studies reporting the isolation of Salmonella from clinically healthy dogs, according to team leader Erika Ganda, assistant professor of microbiomes of the Food Animals, Penn State College of Agricultural Sciences. A major concern, she explained, is the proximity of humans and pet dogs which creates many opportunities for Salmonella “zoonosis” – the disease transmitted to humans from animals – and animal management decisions of company involving food contamination, improper food handling, or both can increase the likelihood of infection.
Antimicrobial-Resistant Salmonella Investigation
To study antimicrobial-resistant Salmonella and the zoonotic potential of non-typhoidal Salmonella isolated from dogs and humans, researchers leveraged existing biomonitoring infrastructure. Using the U.S. Food & Drug Administration’s Veterinary Laboratory Investigation and Response Network, they identified all non-typhoidal Salmonella strains isolated from domestic dogs between May 2017 and March 2023.
Next, they compared the timing and location of these 87 cases with strains isolated from humans in the National Center for Biotechnology Information database maintained by the National Library of Medicine of
” data-gt-translate-attributes=”({“attribute=”” tabindex=”0″ role=”link”>National Institutes of Healthwhich provides access to biomedical and genomic information. They found 77 suspected cases of zoonosis – meaning the bacteria passed from a pet dog to a human – comprising 164 strains, collected from 17 states across the United States.
Strains isolated from dogs included various serotypes or distinct variations within the
” data-gt-translate-attributes=”({“attribute=”” tabindex=”0″ role=”link”>species of bacteria, most of which are clinically relevant to human health, the researchers reported. Although the datasets did not contain information on the severity of infection or treatments, the researchers found that all identified strains had antimicrobial resistance genes for drug classes deemed critical or very important by the World Health Organization.
“We identified 16 non-typhoidal Salmonella isolates from humans closely related to more than one of the six strains associated with dogs,” said Sophia Kenney, a student in the Molecular, Cellular and Integrative Biosciences doctoral program and the Department of animal sciences, who led the study. “Collectively, our data highlight the importance of antimicrobial stewardship and sustained biosurveillance beyond human and agriculture-associated veterinary medicine, using a One Health framework, which considers all points of transmission, including pets. One Health is an approach that recognizes that the health of people is closely linked to the health of animals and our shared environment.
Antimicrobial stewardship in companion animal veterinary medicine is crucial to mitigating antimicrobial resistance under the One Health model, Kenney explained.
“Especially in the case of Salmonella, we think about the role of agriculture and transmission – we think about eggs, beef. But the fact is, we don’t let cows sleep in our beds or lick our faces, but we do it with dogs,” she said. “We have this close connection with pets in general, and we have a very close interface with dogs. So we asked the question: what is the role of pets in the transmission of zoonotic diseases like salmonella, since they can catch it. Salmonella infections in dogs are not common, but we are aware of foodborne outbreaks linked to pet treats or contact with contaminated pet food and improper food handling.
Concrete examples and preventive measures
Study co-author Nkuchia M’ikanatha, senior epidemiologist for the Pennsylvania Department of Health and affiliated researcher with the Penn State Department of Food Sciences, referred to an outbreak of multidrug-resistant Salmonella infections in people linked to pig ear pet treats in the United States. A few years ago, it sickened 154 people in 34 states.
“It reminds us that simple hygiene practices such as hand washing are necessary to protect both our four-legged friends and ourselves: our dogs are part of the family, but even the healthiest puppy health can carry Salmonella,” he said. “Salmonella is a human microbe par excellence, its presence being closely linked to our history since the dawn of agriculture. New research suggests that this pathogen may have obscured humanity for around 10,000 years, coinciding with the rise of animal domestication. With nearly 40% of Pennsylvania households and more than half of U.S. households including dogs, we must respect the ongoing threat of Salmonella and remain vigilant to prevent its spread within our families.
Bacteria are never entirely “bad” or “good”: their role depends on the context, Ganda emphasized. While some bacteria, like salmonella, can pose serious health risks, others are essential to maintaining our health and that of our pets. It’s important to stay vigilant and informed about potential risks, especially when living closely with animals, she added.
“At the same time, several studies highlight the important physical and mental health benefits of owning a dog, including reduced stress and increased physical activity,” Ganda said. “Our goal is not to discourage pet ownership, but to ensure that people are aware of the potential risks and take simple steps, such as practicing good hygiene, to keep their families and loved ones safe. four-legged companions.”
Reference: “Antimicrobial resistance and zoonotic potential of non-typhoidal salmonella from domestic dogs” by Sophia M. Kenney, Nkuchia M. M’ikanatha and Erika Ganda, November 15, 2024, Zoonoses and public health.
DOI: 10.1111/zph.13174
This work was supported by funds from the U.S. Department of Agriculture, the U.S. Centers for Disease Control and Prevention, the National Institutes of Health, and the U.S. Food and Drug Administration.
