Dr. Johny E. Elkahwaji, with the University of Wisconsin, Madison, and colleagues, reported phase II data on the vaccine, a formulation containing ten different types of heat-killed uropathogenic bacteria.

Dr. Elkahwaji told Reuters Health that the vaccine was previously tested in Switzerland about 10 years ago in an injection form. "But its use was discontinued because of the side effects," he said.

To test the suppository form of the vaccine, researchers assigned 54 women with recurrent UTIs to one of three treatment groups. One group received six placebo treatments. Another group received six active treatments, one at the beginning of the study and then one at weeks 1, 2, 6, 10 and 14. The third group received three active and three placebo treatments over a similar time frame.

All the women were followed for five months to record side effects and to measure UTI recurrence. The researchers found that 45% of patients in the group receiving six active immunizations experienced repeat infections compared with 89% of placebo-treated women.

Time to re-infection was significantly longer in women receiving initial and booster immunizations compared with those receiving placebo (p=0.02). Specifically, the median time to re-infection for the placebo-only group was 35 days, for the vaccine/placebo group it was 59 days, and for the group that received all six active treatments, longer greater than 160 days.

"No women had significant adverse effects," the investigators found. A few patients experienced "brief vaginal irritation within one day of immunization or bad transient diarrhea."

"The lack of significant adverse effects in over 100 women confirms the safety of the vaccine itself and the immunization method," they conclude.

According to Dr. Elkahwaji, this is the only vaginal vaccine currently being tested for recurrent UTI. "We have FDA approval to continue the commercialization of this vaccine, and we plan to start a multicenter phase III clinical trial," he said.