Antibiotics have long served as a foundation of modern veterinary medicine, especially in livestock animals. Yet a growing public health threat looms as bacteria evolve to these resistant vital drugs.  

A new study from the University of Kentucky’s Martin-Gatton College of Agriculture, Food and Environment published in Antibiotics titled “Multidrug Resistance and Virulence Traits of Salmonella enterica Isolated from Cattle: Genotypic and Phenotypic Insights” reveals that antibiotic resistance in cattle-associated bacteria could have far-reaching implications for human, animal and environmental health. 

Addressing this challenge benefits from a One Health approach, which integrates the health of people, animals and ecosystems into a unified framework. This is the heart of the One Health Center Initiative, one of The Bill Gatton Foundation Grand Challenges, which advances multidisciplinary solutions through education, research and extension. Yosra Helmy, associate professor in the Department of Veterinary Science and One Health Center researcher, led the study in collaboration with lead veterinary microbiologist Erdal Erol. 

Researchers uncovered Salmonella enterica strains isolated from cattle that were resistant to multiple classes of antibiotics and, importantly, carried virulence traits that enhanced their ability to persist and multiply.  

“UK researchers are now working to better understand the mechanisms behind these traits, to develop new strategies to halt their transmission and identify more effective treatments,” Helmy said. “Antibiotic resistance isn’t just a clinical problem; it’s an ecological one. Our findings highlight that the farm, food supply and environment are all part of the same resistance puzzle. What happens in animals does not stay in animals.” 

Impact on One Health 

Grounded in a One Health framework, the study emphasizes that protecting public health requires coordinated action across interdependent sectors. 

“One Health is not just a concept; it’s a necessity,” Helmy said. “Safeguarding public health demands collaboration at the intersection of veterinary science, human medicine, agriculture and environmental management.” 

Over two years, samples from more than a thousand necropsied cattle were tested in this study, and a small, but important share, carried bacteria resistant to at least three different classes of antibiotics. Several strains showed resistance to carbapenems, powerful antibiotics reserved for life-threatening human infections.  

Although Salmonella enterica was the main focus of the study, many findings point to a broader problem that could affect public health, veterinary care and the environment. 

“The detection of carbapenem-resistant genes in animal isolates is particularly worrisome,” Helmy said. “These are drugs we use only when others fail, and their effectiveness is now under threat from resistance traits emerging outside hospital walls.” 

Beyond resistance, the study also revealed that these Salmonella enterica strains possessed genes related to biofilm formation, adhesion and motility, factors that enable bacteria to survive disinfection, cling to surfaces and spread between environments. This means they can persist on farm equipment, evade sanitation in processing plants and travel through soil or water runoff. 

“These bacteria are stealthy and resilient,” Helmy said. “Biofilms are like a biological armor, once these pathogens form them, they’re incredibly hard to eliminate.” 

Helmy emphasizes that resistant bacteria emerging in livestock are not isolated threats, but they can move through ecosystems and eventually affect people. 

Helmy said the research team stressed that rapid, farm-side diagnostic tests can help veterinarians target the right drug quickly, while stricter sanitation and waste management plans can block escape routes that let resistant germs flow from barns to waterways.  

The research team have begun sequencing the full genomes of the most worrisome strains to map how resistance genes spread among animals, wildlife, environment and human populations in the region. 

“This work underscores why keeping antibiotics effective demands cooperation across medicine, agriculture and environmental science,” Helmy said. “While Salmonella remains a familiar headline in food safety discussions, it serves here as a clear example of how drug-defiant microbes can emerge quietly in one corner of the food chain and threaten the rest of it. By monitoring these pathogens and tightening control measures now, the One Health community hopes to safeguard treatments that people, pets and livestock all depend on.” 

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Writer: Jordan Strickler, jstrickler@uky.edu              

University of Kentucky alum and former trustee Carol Martin “Bill” Gatton bestowed a transformational $100 million gift to the college through The Bill Gatton Foundation. It is the largest gift to the university in its history. 

Four Pillars of The Bill Gatton Foundation’s gift are (1) Scholarships and other initiatives for Student Success, (2) Companion Animal Program, (3) 21st Century Capital Projects and New Initiatives Fund and (4) Faculty Research and Innovation/Research Challenge Trust Fund Program. 

The Martin-Gatton College of Agriculture, Food and Environment is an Equal Opportunity Organization with respect to education and employment and authorization to provide research, education information and other services to individuals and institutions that provide equal opportunities for qualified persons in all aspects of institutional operations and do not discriminate on the basis of race, color, national origin, ethnic origin, religion, creed, age, physical or mental disability, veteran status, uniformed service, political belief, sex, sexual orientation, gender identity, gender expression, pregnancy, marital status, genetic information or social or economic status.