Nightly nitrofurantoin pills versus a Lactobacillus/low‑dose estriol vaginal tablet to prevent recurrent bladder infections in postmenopausal women

Is this trial a fit for you?

A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.

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.

Why it matters

Who can join: the full rules

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 it's running

• Faculty of Medicine Ramathibodi Hospital Mahidol University
  Bangkok, Phayatai Ratchathewi, Thailand Recruiting

Study contacts

• Study coordinator: Lappanawat Santitham
• Email: cambellabios@gmail.com
• Phone: +66944314994

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How to take part

1. Review the eligibility criteria above with your treating physician.
2. Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
3. Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.