Study finds poultry as a major source of drug-resistant Campylobacter infections in the U.S.

A new study has identified poultry as the primary source of human Campylobacter infections in the United States, and there are significant concerns about increasing antibiotic resistance.

Researchers from the Ineos Oxford Institute for Antimicrobial Research, using machine learning techniques and data from U.S. national surveillance, have found that 68 percent of Campylobacter cases between 2009 and 2019 originated from contaminated poultry. The findings were published in the Journal of Infection.

Campylobacter causes infections in the intestines of birds and mammals, often transmitted through undercooked meat or contaminated food. The study highlights growing concerns about the rise of antibiotic resistance in bacteria found in the food chain, particularly in poultry, the most consumed meat in the U.S.

Leveraging machine learning for source attribution
The research used genomic data from 8,856 human Campylobacter infection samples and compared them to 16,703 genomes from potential animal sources, including poultry, cattle, wild birds and pork. The study employed advanced machine learning techniques to identify genetic markers in the bacteria, allowing researchers to trace the likely origins of the infections.

The study found that poultry was the leading source of Campylobacter infections, accounting for 68 percent of cases. Cattle were the second-largest contributor at 28 percent, while wild birds and pork played a much smaller role, contributing 3 percent and 1 percent of infections, respectively.

Ben Pascoe, a research fellow at the Ineos Oxford Institute (IOI), emphasized the significance of the data-sharing collaboration.

“The study uses data collected by multiple U.S. public health agencies. By sharing data and expertise, we’ve been able to conduct the largest study of this kind and provide invaluable data on the source of human infections,” Pascoe said.

Antimicrobial resistance on the rise
One of the key concerns highlighted by the study is the growing prevalence of antimicrobial resistance (AMR) in Campylobacter, especially among poultry strains. Over the study period, researchers observed a noticeable increase in AMR genes, particularly among bacteria originating from chicken sources. This poses a significant threat to public health, as infections caused by antibiotic-resistant bacteria are more difficult to treat and can lead to more severe health outcomes.

Professor Samuel Sheppard, who led the research at IOI, warned of the urgent need to address this issue within the poultry industry.

“We’ve shown that not only is poultry a significant reservoir of Campylobacter infections, but that AMR is increasing in livestock, especially poultry. To protect ourselves and our antibiotics, the poultry industry must look to reduce the spread of infection among poultry as a matter of urgency,” Sheppard said.

Implications for food safety and public health
The study’s findings significantly affect public health and food safety policy. With poultry being a major contributor to Campylobacter infections in humans, the research suggests that targeted interventions in the poultry industry could be one of the most effective ways to reduce the incidence of campylobacteriosis and curb the spread of antimicrobial resistance.

Campylobacter infections are among the most common bacterial foodborne illnesses in the U.S., causing symptoms such as diarrhea, fever, and abdominal cramps. In some cases, especially among individuals with weakened immune systems, the infection can lead to severe complications and hospitalization. The rise of antibiotic resistance further exacerbates these risks.

As policymakers and industry leaders work to improve food safety standards, the study underscores the need for enhanced surveillance, better hygiene practices in food production, and reducing antibiotic use in agriculture to help protect public health.

The complete study can be found here.

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