What is the recommended UTI (Urinary Tract Infection) preventive medication?

UTI Preventive Medications

For preventing recurrent UTIs, continuous or postcoital antimicrobial prophylaxis should be used when non-antimicrobial interventions have failed, with methenamine hippurate being the preferred non-antibiotic option for women without urinary tract abnormalities. 1

Non-Antimicrobial Prevention Options (First-Line)

Before considering antibiotics, the following non-antimicrobial interventions should be attempted:

1. Methenamine hippurate (1g twice daily)

   • Strong recommendation for women without urinary tract abnormalities 1
   • Works by releasing formaldehyde in acidic urine

2. Vaginal estrogen (for postmenopausal women)

   • Strong recommendation 1
   • Various formulations: vaginal rings, inserts, or creams
   • Restores vaginal microbiome and reduces UTI frequency

3. Increased fluid intake

   • Weak recommendation for premenopausal women 1
   • Additional 1.5L of water daily

4. Probiotics

   • Weak recommendation for strains proven effective for vaginal flora regeneration 1
   • Particularly lactobacillus-containing products

5. Cranberry products

   • Weak recommendation with contradictory evidence 1
   • Products containing proanthocyanidin levels of 36 mg are preferred

6. D-mannose

   • Weak recommendation with contradictory evidence 1
   • Patients should be informed of limited evidence

Antimicrobial Prophylaxis (When Non-Antimicrobial Options Fail)

Continuous Prophylaxis Options:

• Trimethoprim-sulfamethoxazole: 40/200 mg daily or 40/200 mg three times weekly 1, 2
• Nitrofurantoin: 50-100 mg daily 1

Postcoital Prophylaxis Options:

• Trimethoprim-sulfamethoxazole: 40/200 mg or 80/400 mg once after intercourse 1, 2
• Nitrofurantoin: 50-100 mg once after intercourse 1

Algorithm for UTI Prevention

1. Confirm diagnosis of recurrent UTIs:

   • ≥2 culture-positive UTIs in 6 months or ≥3 in one year 1
   • Obtain urine culture before starting treatment 1

2. Start with lifestyle modifications:

   • Increased fluid intake
   • Proper urogenital hygiene
   • Void after sexual intercourse

3. Select appropriate interventions based on patient factors:

   • Postmenopausal women: Start with vaginal estrogen with/without lactobacillus probiotics 1
   • Premenopausal women with post-coital infections: Consider low-dose antibiotic within 2 hours of sexual activity 1
   • All patients: Consider methenamine hippurate as first non-antibiotic option 1

4. If non-antimicrobial interventions fail, consider antimicrobial prophylaxis:

   • Select based on prior organism identification and susceptibility
   • Consider antibiotic stewardship principles
   • Counsel patients about potential side effects 1

Important Caveats

• Avoid treating asymptomatic bacteriuria as this promotes resistance without clinical benefit 1, 3
• Do not perform surveillance urine cultures in asymptomatic patients 3
• Self-administered short-term antimicrobial therapy can be considered for patients with good compliance 1
• Trimethoprim-sulfamethoxazole should be avoided in the first trimester of pregnancy (risk of neural tube defects) and third trimester (risk of kernicterus) 3
• Fluoroquinolones should be reserved as last resort due to serious safety issues and to preserve effectiveness 3

Research shows that prophylactic antibiotics are highly effective during the treatment period, with infection rates of 0.0-0.15 per patient-year compared to 2.8 infections per patient-year with placebo 4. However, the protective effect is limited to the period when antimicrobials are taken, with many patients experiencing recurrence within months after discontinuation 5, 6, 7.