What is the definition of a recurrent urinary tract infection (UTI)?

Definition of Recurrent Urinary Tract Infection (rUTI)

Recurrent UTI is defined as 2 or more symptomatic episodes within 6 months OR 3 or more episodes within 12 months. 1, 2

Standard Definitions Across Guidelines

The most widely accepted definition, which aligns with FDA criteria, specifies:

• ≥2 symptomatic UTI episodes in 6 months, OR 1, 2
• ≥3 symptomatic UTI episodes in 12 months 1, 2, 3

However, it's important to note that no universal consensus exists in the literature, and definitions vary across studies, which complicates research interpretation. 1

Key Qualifying Criteria

For an infection to count toward the definition of recurrence, there must be:

• Complete symptom resolution between episodes (at least 2 weeks symptom-free) 1, 3
• Documented symptomatic episodes (not just asymptomatic bacteriuria) 1, 2
• At least one episode verified by urine culture showing ≥100,000 organisms/mL 1, 2

Mechanisms of Recurrence: Critical Distinction

Understanding the mechanism helps guide management:

Reinfection (Most Common)

• New infection occurring >2 weeks after symptomatic cure 1, 4
• Caused by a different pathogen (or same organism from external source) 1, 4
• Accounts for the majority of recurrent UTIs in otherwise healthy women 1

Relapse/Persistent Infection

• Same organism recurring within 2 weeks of treatment completion 1, 4
• Bacterial persistence without symptom resolution despite therapy 1, 4
• Suggests underlying structural abnormality (calculi, diverticula, foreign bodies, incomplete voiding) requiring imaging workup 1, 4

Clinical Pitfall to Avoid

Do not confuse uncomplicated recurrent UTI with complicated UTI. Patients with rapid recurrence (within 2 weeks) or bacterial persistence should be reclassified as complicated UTI and require imaging to identify treatable structural causes. 1, 4 Standard recurrent UTI in women without risk factors and with appropriate treatment response does not require routine imaging. 1

When Prophylaxis Should Be Considered

Women meeting the definition of rUTI (≥3 infections over 12 months) may benefit from prophylactic strategies after behavioral modifications have been attempted. 1