Urinary Tract Infection

The What, Why, and How.

Urinary tract infections result from the presence of pathogenic organisms. Half of all women develop a urinary tract infection at least once. Twenty percent have at least one UTI per year. Women are at particular risk due to a short urethra and proximity of the urogenital meatus to the anus.

Although less common for men, increased UTI frequency occurs in both sexes over the age of 65.

Additional risk factors for urinary tract infection include catheterization, diabetes mellitus (DM), and renal failure (elevated serum creatinine levels).

UTI Symptoms

  • Dysuria
  • Increased urination (frequency, urgency)
  • Nocturia
  • Bladder tenderness
  • Fever (occasional)

Urinary tract infections occurring at or below bladder level (cystitis, urethritis, prostatitis) are classified as lower UTIs. Upper UTIs (pyelonephritis, intrarenal abscess, perinephric abscess) occur above bladder level. Complicated UTIs involve functional or structural abnormalities, but not all UTIs present with clinical symptoms. Fully 80 percent of these asymptomatic infections are self-limiting.

Centers for Disease Control and Prevention (CDC) Diagnostic Criteria

For patients over one (1) year of age:

Diagnostic Definition Symptoms Laboratory Criteria
Symptomatic UTI At least one of the following:
Fever (>38°C)
Suprapubic tenderness

≥105 CFU/mL

≤ 2 species  
Asymptomatic UTI
History of urinary catheter None

Indwelling catheter < 7 days of positive culture 

105 CFU/mL

 2 species

(one occurrence)
No history of urinary catheter None

No indwelling catheter within 7 days of first (1/2) urine cultures

≥105 CFU/mL

≤ 2 species

(more than one occurrence)