Treating C. difficile with antibiotics could actually increase a person’s risk of transmitting the bacteria, even weeks after physical symptoms have disappeared, according to recently published research.

To determine the risk of spreading the infection across healthcare settings, researchers at the Wellcome Trust Sanger Institute created a “mouse hospital,” which replicates many human environmental conditions. When C. difficile-infected mice were treated with antibiotics, the number of infectious spores they shed and the rate at which they shed them dramatically increased, according to researchers. What’s more, when those mice were treated over a long period of time, they continued to shed those spores at an accelerated rate, despite showing no physical symptoms. In some cases, shedding occurred for weeks after treatment stopped.

The implications of the report could affect infection control measures in healthcare settings, with researchers recommending widening the scope of infection control efforts to include all those receiving a course of antibiotics. The report appears in the journal Infection and Immunity.