May 31, 2005

Study reveals link between poultry antibiotics and bacterial resistance

According to a study by the Johns Hopkins Bloomberg School of Public Health, various factors that encourage Campylobacter bacterial resistance to poultry antibiotics have been highlighted. Other food-borne bacteria that infect humans were also observed to develop antibiotic resistance.

There was also evidence suggesting that chickens raised without antibiotics are less likely to carry antibiotic-resistant strains of Campylobacter. Furthermore, the study found that Campylobacter can persist in poultry populations and products long after poultry farmers stop using the antibiotics.

Fluoroquinolones (FQs), a class of antimicrobials used to control the bacterium Escherichia coli in broiler chickens was the focus of the study. The study involves examining and comparing chicken products from a sample of poultry producers using antibiotics against those who do not.

Based on the study findings, the researchers concluded that conventional products were up to 460 times more likely to carry resistant strains than their antibiotic-free counterparts, and abstinence from FQ use by poultry producers did not increase the likelihood of Campylobacter contamination. FQ resistance in conventional products also persisted for one year after the producers stopped using them.

However, even without antibiotics, resistant Campylobacter may stay in the chicken over time as a result of residual contamination in poultry houses. Biofilms in water distribution systems could serve as breeding grounds for resistant Campylobacter populations. The researchers suggest the need to further improve poultry house cleaning and disinfection.

Other measures suggested by the researchers include monitoring the levels of FQ-resistant strains in the food supply. Supplemented agar may be preferred in detecting resistant strains of Campylobacter than conventional methods because it is much more sensitive.