( nd similar genes may be present in othe...)One bacteria stops another on contact

Low said that one possible interpretation is that bacteria use this system to eliminate competition in the environments they grow in. "Another possibility is that the bacteria use the CDI system to shut themselves off inside a host, going into a dormant state where they may go undetected by the immune system," he said.

Thousands of women in this country have chronic urinary tract infections, noted the scientists. The disease seems to go away for awhile, then something triggers recurrence of the disease.

Work by Scott Hultrgen at Washington University has indicated that E. coli cells may hide in the walls of the bladder and urinary tract in a dormant state, explained Low. It is possible that the newly discovered CDI system contributes to this process.

"By studying the CDI system, we hope to understand more about how bacteria interact with each other and with their hosts, and how these interactions contribute to disease," said Aoki.

The findings may have repercussions outside of better understanding of urinary tract infections. Other diseases may have similar mechanisms, according to the scientists. "This research is in its infancy, but opens the door for exploration of the roles of contact-dependent growth inhibition in urinary tract infections and possibly other diseases," said Low.

"Aoki has discovered an entirely new phenomenon," explained Low, who has studied E. coli for over 20 years. "It is fascinating that bacteria have developed a system by which one cell can contact another and inhibit its growth."