From American Urologic Society (AUS) Best-Practice Statement: Recurrent UTI in Adult Women November 2023 - Volume 29 - Issue 11 Brubaker, L. et al.

You will see in this article that the AUS correctly recommends vaginal estrogen for Recurrent UTI’s  which FGI has long since advocated. Notice the study also looked at the presence of Lactobacilli. While they did not look at the concentration of Lactobacilli, there was a dramatic difference between the presence in vaginal treated women compared to those not receiving estrogen. Also notice that oral estrogen was not effective. All these findings are congruent with the Fowler Gyn Approach.

“Vaginal estrogen should be used whenever possible in hypoestrogenic women with recurrent UTI because it clearly decreases UTI recurrence. In a randomized, double-blind, placebo-controlled trial of 93 postmenopausal women assigned to topically applied intravaginal estriol cream (0.5 mg estriol in vaginal cream daily for 2 weeks, followed by twice weekly for 8 months) vs placebo, UTI incidence in the treatment group decreased significantly (0.5 vs 5.9 episodes per patient-year). In addition, after 1 month of treatment, lactobacillus appeared in 60% of the estrogen-treated group and none of the placebo group. In another multicenter randomized noncontrolled trial of 108 postmenopausal women with recurrent UTI randomized to vaginal estrogen ring (2 mg estradiol, 1 ring for 12 weeks, for a total of 36 weeks), the vaginal estrogen ring significantly decreased UTI occurrences and prolonged the time to next occurrence. A Cochrane review of these studies indicated that vaginal cream may be more effective than the vaginal ring, although significant heterogeneity in these studies prohibited pooling of findings. A systematic review of vaginal estrogen treatment of vulvovaginal atrophy found moderate-quality evidence of decreased UTI risk in women with vaginal atrophy using vaginal estrogen. Studies comparing vaginal estrogen and antibiotics are inconclusive.  Oral estrogen has not been shown to be effective and should not be used for recurrent UTI prevention.”