American scientists say they are a step close to a vaccine that could prevent majority of urinary tract infections.

UTI is caused by E.coli bacteria and the vaccine could potentially save billions of dollars in health care costs globally. It costs $ 3.5 billion to treat UTI every year and nearly 40% of women will experience UTI in their lifetime. E.coli bacteria cause over 80% of UTI infections.

Researchers from the University of Michigan discovered key differences on how the E.coli bacteria behave in women and mice in experiments. They found specific surface structures in the bacteria, found in mouse infections were not found in the human samples. The study is published in PLoS Pathogens.

“If we want to prevent infections in humans, we need to look at what’s going on with the bacteria while it’s in humans,” said Harry L.T. Mobley, Ph.D., the study’s senior investigator and the Frederick G. Novy Professor and chair of the U-M Department of Microbiology and Immunology. “We’re not looking to make the world safer for mice."

“That tells us it’s more complicated than we thought and that there are some important differences we need to study in human infections,” said research fellow Erin C. Hagan, one of the study’s two first authors.