Photo credit: Nick Saltmarsh

A study published in the scientific journal PLOS ONE  tested swine from four different European countries—Denmark, France, Italy, and Sweden—and found that those raised on organic farms consistently harbored less antibiotic resistant E. coli than swine raised on conventional farms. Samples were taken from the colon or manure from 300 organic pigs from 112 conventional herds and 300 conventional pigs from 112 conventional herds. E. coli was isolated from each sample and tested for resistance against 10 common antibiotics. Researchers also quantified the proportion of E. coli collected that were resistant to tetracycline. In all four countries, organic pigs were significantly less likely to harbor E. coli resistant to the antibiotics ampicillin, streptomycin, sulphonamides or trimethoprim. In addition, in France and Italy, organic pigs were significantly less likely to harbor E. coli resistant to the antibiotics chloramphenicol, ciprofloxacin, nalidixic acid, and gentamicin. No E. coli were found to be resistant to the final antibiotic, cefotaxime. The proportion of E. coli that exhibited resistance to tetracycline was lower in organic farms as well with the exception of Sweden, where tetracycline resistance was low across the board. “For all four countries, resistance was substantially lower in organic than conventional pigs…This knowledge, together with a continued effort to improve animal health and thereby reduce the overall need for antibiotics, would be valuable to reduce antibiotic resistance without compromising animal welfare,” the authors concluded.