Culture-confirmed Bacterial Species Causing Recurrent Urinary Tract Infection Among Adult Women.

IMPORTANCE

Approximately 60% of adult women experience at least 1 urinary tract infection, and more than 25% experience multiple recurrences. If persistent bacterial reservoirs in the urinary tract contribute to the high incidence of recurrent infections, then repeated episodes should be disproportionately caused by the same bacterial species.

OBJECTIVES

The obectives of this study were to estimate, among women with recurrent urinary tract infection, the proportion of recurrences due to the same bacterial species and to identify host characteristics associated with species consistency across episodes.

STUDY

DESIGN

This study was a retrospective observational study of adult women with recurrent urinary tract infections. Urinary tract infection was defined as a urine culture positive for ≥10,000 colony-forming units of a single bacterial species, plus a diagnosis related to relevant signs or symptoms. We calculated the proportion of infection pairs due to the same bacterial species. To identify host characteristics associated with species consistency across episodes and to account for repeated pairs, we used logistic regression with generalized estimated equations.

RESULTS

One hundred eighty-one women experienced 496 urinary tract infection episodes. The median age was 49 years, and the median interval between infections was 88 days. Among 315 episode pairs, the same bacterial species was identified in 239 pairs (75.9%). Women over age 65 years were significantly less likely to have the same bacterial species across episode pairs (relative odds 0.35, 95% CI: 0.17, 0.70). Race, ethnicity, body mass index, menopause status, diabetes, and time between infections were not significantly associated with species consistency.

CONCLUSIONS

Consistent bacterial species cause most sequential infections among women with recurrent urinary tract infections, especially in younger women. This observation would be consistent with the hypothesis that bacterial reservoirs may contribute to recurrent urinary tract infections.