I. Definition and Overview
- UTIs are infections involving any part of the urinary tract: urethra, bladder, ureters, or kidneys.
- Most are caused by ascending infection of bacteria from the urethra.
- Common in females due to shorter urethra and proximity to anus.
IV. Pathogenesis
- 1. Colonization of periurethral area → often from gut flora
- 2. Ascending infection into bladder (cystitis), then kidneys (pyelonephritis)
- 3. Virulence factors:
- E. coli: adhesins (P pili, type 1 fimbriae), hemolysin, siderophores
- Proteus: urease alters urine pH
- Biofilm formation in catheterized patients
VI. Diagnosis
A. Specimen Collection
- Midstream clean-catch urine (preferred)
- Catheter aspirate
- Avoid swabs
B. Tests
UTI Treatment
Uncomplicated UTIs are treated with nitrofurantoin (5 days), TMP-SMX (3 days), or fosfomycin (single dose). Fluoroquinolones are reserved due to resistance concerns.
Complicated UTIs need broad-spectrum antibiotics like ciprofloxacin or ceftriaxone for 7–14 days, depending on severity. Always address underlying causes like catheters or obstruction.
Pyelonephritis (kidney infection) starts with IV ceftriaxone or ciprofloxacin, then switches to oral antibiotics for 10–14 days total.
Catheter-related UTIs require catheter removal/change and antibiotics targeting resistant organisms (e.g., ciprofloxacin, piperacillin-tazobactam).
Asymptomatic bacteriuria is only treated in pregnancy and before urologic procedures