Newswise — Antibiotics are common tools for fighting pathogenic bacteria in swine production. Iowa State University researchers have found that certain antibiotics encounter more resistance from Campylobacter coli than other antibiotics, with some variation of resistance levels between farms. Researchers are still looking for more clues to determine the significance of the variations.
"If we can eventually figure out what the actual risk factors are associated with resistance we'll be able to manage that and reduce the risk," said Qijing Zhang, an ISU professor of veterinary microbiology who managed the project for the Food Safety Consortium.
Zhang's team, in collaboration with Irene Wesley at the U.S. Department of Agriculture National Animal Disease Center, gathered C. coli isolates from different production stages at two Iowa swine farms and tested their ability to resist five different antibiotics. The pathogens were unable to resist two antibiotics " gentamicin and meropenem -- but there were varying levels of resistance to three other antibiotics.
Those three antibiotics' abilities to stave off C. coli varied among each other and between the farms. The levels ranged from 65 percent of C. coli isolates on one farm resisting one antibiotic to 7.3 percent on the other farm. The antibiotic doxycycline encountered the most resistance, with the antibiotics erythromcin and ciprofloxacin encountering lower resistance rates.
"Two of the three antibiotics to which we noticed Campylobacter developed a resistance were those that are used fairly often in swine production," Zhang said.
The researchers also noticed that Campylobacter is prevalent within both swine and poultry production systems. "That has nothing to do with the production management," Zhang noted. "It's just that Campylobacter is naturally associated with swine and poultry."
The ISU researchers are considering following with another phase of research into the subject. "We're not going to abandon this project," Zhang said. "This is a long-term interest for our research."
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