All things considered, urinary tract infections (UTIs) ought not be as prevalent as they are (about 150 million people develop UTIs each year, and they are the most common of bacterial infections).  This is because the bladder is actually a very hostile environment for E. coli bacteria – the most common cause of the infection – to grow. Thebacteria that do thrive in your bladder are the ones that have figured out how to scavenge iron from their hosts.

These E. coli draw upon small iron-grabbing molecules, called siderophores, to stay alive in your bladder. But what if a battalion of those same thieving molecules could be put to work against the E. coli, robbing them of what they need to survive?

Scientists from the University of Michigan Medical School came up with that idea and have turned it into what is essentially a vaccine against UTIs. It currently works in mice, and a human vaccine is likely several years away, but the groundwork for success has been laid out.

The same research team at UMichigan had success in preventing UTIs using a vaccine made of proteins from the bacteria, called uropathogenic Escherichia coli or UPEC. Neither the protein approach nor the siderophore approach provided complete protection, but the scientists are hopeful that the two approaches together might.

UPEC is responsible for more than three-quarters of UTIs in otherwise healthy women, and the bacteria produce “stealth” siderophores that evade the host immune system and are unique to them. The researchers believe that makes these molecules good candidates for a vaccine without unintended consequences.

UTI care in the United States costs more than $3.5 billion a year, and UTIs will affect half of all women at one point in their lives. In half of those, the infection will recur inside of a year. About 4 million women suffer continuous UTIs. Women suffering recurrent UTIs are the most likely candidates for a vaccine, says first author and research fellow Laura Mike, PhD.

“We saw efficacy more in the kidney than in the bladder, suggesting that this approach may be most useful in preventing advanced UTIs,” says Mike. “Our next challenge is creating a combination vaccine that also employs proteins that UPEC bacteria use to bind their iron-laden siderophores, and test other adjuvants to increase the response.”

The research has been published in the Proceedings of the National Academy of Sciences.