Nightly nitrofurantoin pills versus a Lactobacillus/low‑dose estriol vaginal tablet to prevent recurrent bladder infections in postmenopausal women
Evaluating Urinary Microbiome Modulation :An RCT of Antibiotic vs Gynoflor Prophylaxis in Postmenopausal Women With Recurrent Cystitis
This trial will try whether nightly nitrofurantoin or a vaginal Lactobacillus/low‑dose estriol tablet (Gynoflor) better prevents recurrent urinary tract infections in postmenopausal women.
Quick facts
| Phase | Phase 4 |
|---|---|
| Study type | Interventional |
| Enrollment | 100 (estimated) |
| Ages | 40 Years and up |
| Sex | Female |
| Sponsor | Mahidol University Academic / other |
| Locations | 1 site (Bangkok, Phayatai Ratchathewi) |
| Trial ID | NCT07186465 on ClinicalTrials.gov |
What this trial studies
This open‑label, parallel‑group randomized trial enrolls postmenopausal women with recurrent cystitis and randomizes them 1:1 to nightly oral nitrofurantoin 100 mg for six months or a Gynoflor vaginal tablet (daily for 14 days, then twice weekly to month 6). The primary outcome is the proportion of participants with a qualifying rUTI within six months; secondary outcomes include time to first recurrence, antibiotic resistance patterns in breakthrough infections, symptom change by the Thai RUTISS, and urinary microbiome measures (Lactobacillus abundance and community diversity by qPCR and 16S rRNA). Key assessments occur at baseline and month 6 with urinalysis, culture, microbiome sampling, and kidney function testing, while adherence and adverse events are tracked via twice‑weekly phone/LINE contacts. The trial compares clinical recurrence and microbiome modulation between an antibiotic prophylaxis strategy and a microbiome‑modulating vaginal product.
Who should consider this trial
Good fit: Postmenopausal women aged 40 or older with a history of recurrent urinary tract infections who can use a vaginal product and commit to six months of follow‑up and twice‑weekly contacts.
Not a fit: Women with a current symptomatic UTI at enrollment, significant renal impairment or other contraindications to nitrofurantoin or Gynoflor, planned urologic procedures during the study period, or active vaginal conditions preventing product use may not benefit or be eligible.
Why it matters
Potential benefit: If successful, this could provide an effective non‑antibiotic prevention option that reduces recurrent UTIs and lowers long‑term antibiotic exposure and resistance.
How similar studies have performed: Antibiotic prophylaxis is known to reduce rUTI risk and vaginal lactobacilli or low‑dose estriol have shown promise in smaller studies, but direct randomized comparisons against nightly antibiotic prophylaxis are limited.
Eligibility criteria
Show full inclusion / exclusion criteria
Inclusion Criteria: * Female, postmenopausal, age ≥40 years * Clinical history of recurrent urinary tract infection (rUTI) as assessed by the investigator * Able and willing to take assigned prophylaxis for 6 months * Able to attend baseline and Month 6 study visits and provide urine samples * Able to provide written informed consent * Willing and able to complete twice-weekly phone/LINE follow-ups Exclusion Criteria: * Current symptomatic UTI at enrollment (may be treated and reconsidered after resolution) * Known hypersensitivity or contraindication to nitrofurantoin or to the Lactobacillus/estriol vaginal tablet (Gynoflor) or their excipients; significant renal impairment or other label-based contraindications to nitrofurantoin per local practice * Planned urologic surgery or procedure expected during the 6-month study period * Recent bacterial vaginosis (e.g., within the past month) or active vulvovaginal skin disorders precluding vaginal product use * History of hormone-dependent malignancy (e.g., breast, uterine, or cervical cancer) or unexplained abnormal vaginal bleeding * Significant liver disease (e.g., active hepatitis) or other conditions judged by the investigator to make participation unsafe * Participation in another interventional trial that could interfere with outcomes * Withdrawal of consent or severe adverse event requiring discontinuation
Where this trial is running
Bangkok, Phayatai Ratchathewi
- Faculty of Medicine Ramathibodi Hospital Mahidol University — Bangkok, Phayatai Ratchathewi, Thailand (Recruiting)
Study contacts
- Study coordinator: Lappanawat Santitham
- Email: cambellabios@gmail.com
- Phone: +66944314994
How to participate
- Review the eligibility criteria above with your treating physician.
- Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
- Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.