A new study shows scientists are starting to understand how antibiotic resistance from open-air farms can travel through the air to spread to human populations. Share on Pinterest The researchers sampled feedlot dust in the air upwind and downwind of the cattle farms.

Image credit: Brett Blackwell/TTU. A team from the Institute of Environmental and Human Health at Texas Tech University (TTU) in Lubbock, TX, analyzed air samples around feedlots at cattle farms in the Southern High Plains that lie in northwestern Texas. In the journal Environmental Health Perspectives, they report how they found evidence of feedlot-derived bacteria, antibiotics and bits of DNA that code for antibiotic resistance, in the samples. The study is thought to be the first to document evidence of airborne transmission of antibiotic resistance from an open-air farm setting. The researchers accept that while they couldn’t assess whether the amounts of the materials they found were dangerous to humans, the results shed light on previously unanswered questions about which routes antibiotic-resistant bacteria could be using to travel long distances to places inhabited by humans.

70% of antibiotics are used in animal farming Senior author Phil Smith, an associate professor of terrestrial ecotoxicology at TTU, says we are all fairly sure that antibiotic resistance comes from extensive use of antibiotics in animal farming, where around 70% of all antibiotics are used. He says we also know bacteria are very “promiscuous” about swapping and sharing their genetic material, which crosses easily into other species. So we know the mechanism through which resistance develops. But what we don’t know so much about is how the resistant bacteria travel and move in the environment, says Prof. Smith. In an attempt to address some of the questions surrounding this mystery, the team analyzed air samples taken upwind and downwind of each feedlot.