Researchers at Worcester Polytechnic Institute in Massachusetts have found that compounds in cranberries are able to alter E. coli bacteria. Associate professor Terri Camesano and graduate students Yatao Liu and Paola Pinzon-Arango have used the atomic force microscope and other sophisticated tools to study how a group of tannins found primarily in cranberries interact with bacteria at the molecular level.

The cranberry compounds prevent E. coli from adhering to cells in the body -- a necessary first step in infections such as urinary tract infections -- because:

-- The chemical changes caused by cranberry juice create an energy barrier that keeps the bacteria from getting close to the urinary tract lining.

-- The adhesive forces between E. coli and cells of the urinary tract are greatly reduced when at least a 5 percent solution of cranberry juice cocktail is present.

-- E. coli grown in cranberry juice are unable to form biofilms. Biofilms, clusters containing high concentrations of bacteria, are required for infections to develop.