The images reveal for the first time that E. coli, which are responsible for 80 to 90 percent of all UTIs, pass through at least four distinct developmental stages during the course of an infection. Researchers hope to further define these stages and use them as guides in the search for new drugs.
The study, to be published this week in the early online edition of the Proceedings of the National Academy of Sciences, also reveals that bacteria will sometimes shift into an inactive state, creating reservoirs of infection within the bladder that might be responsible for some of the recurrent UTIs that plague many women.
To image the bacteria in action through a videomicroscope, researchers made the bacteria glow by adding a phosphorescent green protein. The movies show the bacteria rapidly changing themselves and their interactions with each other to collectively hijack bladder cells and use them as safe havens for replication.
"It just boggles the mind what these bacteria can do, in terms of sensing and responding to their environment and each other," says Scott J. Hultgren, Ph.D., the Helen Lehbrink Stoever Professor of Molecular Microbiology and lead investigator of the study. "This has never been seen before in live host tissue, and parts of this process are probably present in a multitude of different kinds of pathogens."
UTIs, which mainly occur in women, are the second most common type of bacterial infection. Linked to poor hygiene, sexual behavior and migration of intestinal flora, they are believed to cause around $1.6 billion in medical expenses every year in the United States. Scientists estimate half of
Contact: Michael C. Purdy
Washington University School of Medicine