Researchers from The University of Texas at Austin have found that honeybees treated with a common antibiotic were half as likely to survive the week after treatment compared with a group of untreated bees, a finding that may have health implications for bees and people alike. The scientists found the antibiotics cleared out beneficial gut bacteria in the bees, making way for a harmful pathogen, which also occurs in humans, to get a foothold. The research is the latest discovery to indicate overuse of antibiotics can sometimes make living things, including people, sicker. The UT Austin team, led by professor Nancy Moran and postdoctoral researcher Kasie Raymann, found that after treatment with the common antibiotic tetracycline, the bees had dramatically fewer naturally occurring gut microbes — meaning healthy bacteria that can help to block pathogens, break down toxins, promote absorption of nutrients from food and more. They also found elevated levels of Serratia, a pathogenic bacterium that afflicts humans and other animals, in the bees treated with antibiotics, suggesting that the increased mortality might have been a result of losing the gut microbes that provide a natural defense against the dangerous bacteria. “Our study suggests that perturbing the gut microbiome of honeybees is a factor, perhaps one of many, that could make them more susceptible to declining and to the colony collapsing,” Moran said. “Antibiotics may have been an underappreciated factor in colony collapse.” The results are reported today in the online journal PLOS Biology.