UTI treatment
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Urinary Tract Infection (UTI) Treatment
Classification Framework
Treatment depends on:
- Extent of infection — cystitis vs. pyelonephritis vs. urosepsis
- Complicated vs. uncomplicated — presence of anatomic abnormalities, indwelling catheter, pregnancy, immunosuppression, male sex
- Local resistance patterns — critical for empiric antibiotic choice
Acute Uncomplicated Cystitis (Women)
First-line agents (preferred due to efficacy, short courses, and minimal impact on normal flora):
| Drug | Dose | Duration |
|---|---|---|
| Nitrofurantoin (macrocrystals) | 100 mg TID or 100 mg BID | 5 days |
| Trimethoprim-sulfamethoxazole | 160/800 mg BID | 3 days |
| Fosfomycin | 3 g single oral dose | 1 day |
| Trimethoprim (alone) | 200 mg BID | 7 days |
Key caveats:
- TMP-SMX should only be used empirically if local E. coli resistance < 20%
- Fosfomycin is appropriate only for uncomplicated cystitis due to E. coli; nitrofurantoin is more effective at microbiologic resolution at 28 days vs. single-dose fosfomycin
- Fluoroquinolones are NOT recommended first-line due to toxicity concerns and resistance promotion
- β-Lactams (e.g., amoxicillin-clavulanate) are ~10% less effective than first-line agents
- Pregnant women: nitrofurantoin and oral cephalosporins are preferred (safe for fetus); avoid TMP in first trimester and near term
Symptom relief: Phenazopyridine 100–200 mg TID after meals for ≤2 days — for dysuria only; must be used with antibiotics (not as monotherapy), as it can mask fever and infection signs.
Men with uncomplicated cystitis: treat for 7 days.
Acute Uncomplicated Pyelonephritis
Initial decision: can the patient be managed orally, or is parenteral therapy needed?
Parenteral (initial):
- IV aminoglycoside (e.g., gentamicin) — associated with better outcomes, especially where oral resistance is high
- IV fluoroquinolone or 3rd-generation cephalosporin are alternatives
Step-down to oral (after 24–48 h of clinical improvement):
- Ciprofloxacin or levofloxacin (5–7 days total)
- TMP-SMX or cefixime (7–14 days total)
- ⚠ Nitrofurantoin and fosfomycin do not achieve adequate renal tissue levels — avoid for pyelonephritis
Total duration: 5–7 days (fluoroquinolones); 7–14 days (other agents)
Complicated UTI
Includes: male patients, catheter-associated UTI, structural/functional urologic abnormalities, immunocompromised, resistant organisms.
Principles:
- Individualize based on site, severity, culture results, and underlying abnormalities
- If symptoms are mild, can await culture results before starting antibiotics
- If severe, start empiric therapy promptly using prior culture history and local antibiograms
Severe/parenteral options:
| Agent | Dosing | Duration |
|---|---|---|
| Plazomicin | 15 mg/kg once daily IV | 4–5 days → oral step-down |
| Meropenem | 1 g IV q8h | 4–5 days → oral step-down |
| Piperacillin-tazobactam | 4.5 g IV q8h | 7 days |
| Fosfomycin IV | 6 g IV q8h | 7 days |
| Meropenem-vaborbactam | 2 g/2 g IV q8h | 4–5 days → oral step-down |
Plazomicin and meropenem-vaborbactam are particularly useful for highly resistant organisms (ESBL, KPC, NDM producers).
⚠ Nitrofurantoin is not appropriate as step-down or primary therapy for complicated UTI.
Recurrent UTI (Women)
Three management strategies:
- Patient-initiated self-treatment: empiric antibiotics at symptom onset (effective for women with infrequent, well-characterized episodes)
- Post-coital prophylaxis: single dose of nitrofurantoin or TMP-SMX after intercourse
- Continuous low-dose prophylaxis: for frequent recurrences (≥3/year)
Catheter-Associated UTI (CAUTI)
- Pyuria and bacteriuria alone in catheterized patients do not indicate UTI — symptoms are required
- Remove or replace catheter when possible
- Culture-directed therapy; avoid treating asymptomatic bacteriuria
Asymptomatic Bacteriuria (ASB)
Treat only in:
- Pregnant women (nitrofurantoin or cephalosporins)
- Patients before urologic procedures with anticipated mucosal trauma
Do not treat ASB in: diabetic women, elderly, catheterized patients, or premenopausal non-pregnant women — treatment increases resistance without clinical benefit.
Sources: Goldman-Cecil Medicine, 27th ed.; Berek & Novak's Gynecology; Comprehensive Clinical Nephrology, 7th ed.; Tintinalli's Emergency Medicine
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