Antibiotic-Resistant Bacteria Identified among Beef-Packing Workers.
Workers in the US cattle industry may be exposed to antibiotic-resistant bacteria from livestock, a finding that has broad implications for occupational health, according to a new study led by a School of Public Health researcher.
In the journal PLOS ONE a research team led by Jessica Leibler, assistant professor of environmental health, found that 3.5 percent of a sample group of beef slaughterhouse workers in the US were exposed to antibiotic-resistant Staphylococcus aureus with genetic markers of livestock adaptation.
While human exposure to pigs and poultry has been associated with livestock-associated S. aureus in workers, this study was the first to document human exposure in the context of beef workers in the US.
Leibler said the study implies a potential role of the beef-production chain in the transmission of antibiotic-resistant bacteria to humans, noting that, “while workers are at the front lines, our findings imply risk to workers’ families, communities, and consumers of beef products.”
Staphylococcus aureus is known to colonize many livestock species, including pigs, poultry, sheep, and cattle, and is also the cause of wide-ranging illness in humans, from skin and soft tissue infections to pneumonia and bacteremia.
Leibler and the research team enrolled 137 workers from an industrial beef-packing plant in Nebraska and tested them for the presence of nasal colonization of S. aureus with a genetic marker of adaptation to livestock. Five workers were colonized with antibiotic- resistant strains of S. aureus that had genetic markers of being from livestock. S. aureus is a normal part of the nasal microbiome in humans, but strains from animals are not typically found among individuals without livestock exposure.
Leibler said there is growing interest in whether the systems involved with industrial livestock production, including the use of antibiotics in the animal growth cycle, may contribute to the emergence of drug-resistant bacteria identified in clinical medicine.
“Studying the workforce in this industry is a way to identify at the source whether bacteria from animals are being transmitted to humans,” she said.
The researchers recommended a larger epidemiologic study to survey both beef-packing workers and community members who do not work in the industry, to determine the role of contact with beef products in the strains of S. aureus identified. They also called for studies that sample livestock for S. aureus during slaughter and production, as well as environmental sampling of slaughterhouse facilities.
Co-authors on the study are from the Milken Institute School of Public Health of The George Washington University; the College of Public Health, University of Nebraska Medical Center; and the Translational Genomics Research Institute.