Recurrent UTIs may be caused by self-infection

San Francisco-One of the most frustrating problems for women with urinary tract infections is to complete apparently successful antibiotic treatment, only to have the infection reoccur.

"Every urologist and every woman who has ever had recurrent UTIs knows how vexing it can be," said Birgit Norinder, a pharmacist in the division of clinical bacteriology, Karolinska University Hospital, Stockholm, Sweden. "The question has always been where the reinfection comes from."

The answer, according to results of a study by Norinder and colleagues, is that "you are likely to be your own reservoir," she said, who reported her group's findings at the annual Interscience Conference on Antimicrobial Agents and Chemotherapy here.

Samples from urine, periurethra, and vagina again were taken from the patients between days 12 and 14 after treatment and again at 28 to 35 days after treatment. All samples were frozen, then analyzed for genetic variation using pulsed-field gel electrophoresis.

Genotyping revealed 73 strains of E. coli in the samples, and electrophoresis showed that the bacterial strains isolated from the three sample sites were identical for 12 of the 17 women on visit one, visit two, and/or visit three. Two patients had two different strains of E. coli on the first visit. Both strains still were present at the second visit for one woman, however only one clone remained at her third visit.

Three other patients had a different strain of E. coli at visit two or at visit three compared with the strain found at their initial pre-treatment visit. Four women had recurrent UTIs during the course of the study, all caused by the same strain as that which was found at their first visit.

"Reinfection is a significant problem for women with recurrent UTIs," Norinder said.