Treatment of Urinary Tract Infections
For uncomplicated lower urinary tract infections (UTIs), nitrofurantoin 100 mg twice daily for 5 days is the recommended first-line treatment, based on high-quality evidence from the Infectious Diseases Society of America and European Association of Urology guidelines. 1
First-Line Treatment Options for Uncomplicated UTIs
- Nitrofurantoin: 100 mg twice daily for 5 days (high-quality evidence) 1, 2
- Fosfomycin: 3 g single dose (moderate evidence, but lower clinical resolution rates compared to nitrofurantoin) 1, 2
- Trimethoprim-sulfamethoxazole (TMP-SMX): 160/800 mg twice daily for 3 days (if local resistance is <20%) 1
- Pivmecillinam: 400 mg twice daily for 5 days (moderate evidence) 1
A 2018 randomized clinical trial demonstrated that 5-day nitrofurantoin treatment resulted in significantly higher clinical resolution rates (70%) compared to single-dose fosfomycin (58%) for uncomplicated UTIs 2.
Treatment for Complicated UTIs
For complicated UTIs, including pyelonephritis:
- Amoxicillin-clavulanate: 875/125 mg every 12 hours (FDA-approved for complicated UTIs) 3
- Ciprofloxacin: 500-750 mg twice daily for 7 days (reserve for more severe infections due to resistance concerns) 1, 4
- Levofloxacin: 750 mg once daily for 5 days 1
- Cephalexin: 500 mg four times daily for 5-7 days 1
For patients with pyelonephritis who cannot take first-line agents, parenteral options include:
- Ceftriaxone or cefotaxime 1
Special Populations
Renal Impairment
For patients with impaired renal function, dosing adjustments are necessary:
- Levofloxacin dosing based on creatinine clearance:
- CrCl ≥50 mL/min: 750 mg once daily for 5 days
- CrCl 20-49 mL/min: 500 mg once daily
- CrCl 10-19 mL/min: 250 mg once daily
- Hemodialysis: 250-500 mg every 48 hours (administer after dialysis) 1
Pregnancy
- Nitrofurantoin: Generally safe except in the last trimester 1
- Cephalexin: Safe option during pregnancy 1
- Avoid TMP-SMX: Contraindicated in first and third trimesters 1
- Avoid tetracyclines: Contraindicated throughout pregnancy 1
Treatment Algorithm Based on UTI Type
Uncomplicated lower UTI in otherwise healthy women:
- First-line: Nitrofurantoin 100 mg twice daily for 5 days
- Alternatives: Fosfomycin 3 g single dose or TMP-SMX 160/800 mg twice daily for 3 days
Complicated UTI/Pyelonephritis:
- Outpatient: Ciprofloxacin 500-750 mg twice daily for 7 days or amoxicillin-clavulanate 875/125 mg twice daily
- Inpatient/severe: Parenteral therapy with ceftriaxone or fluoroquinolones
UTI in patients with allergies to both Augmentin and sulfa drugs:
- Nitrofurantoin (for lower UTI only)
- Cephalosporins (if no severe penicillin allergy)
- Fluoroquinolones (if necessary, considering resistance concerns)
Antibiotic Resistance Considerations
- Fluoroquinolones should be reserved for more serious infections due to increasing resistance rates 1, 5, 6
- Always consider local resistance patterns when selecting empiric therapy 1, 5
- For suspected ESBL-producing organisms, consider nitrofurantoin (for lower UTI) or carbapenems 6
Prevention of Recurrent UTIs
- Increased fluid intake
- Post-coital antibiotics for women with intercourse-related recurrences
- Daily low-dose antibiotic prophylaxis with nitrofurantoin
- Vaginal estrogen for postmenopausal women
- Non-antibiotic alternatives: methenamine hippurate, cranberry products, or lactobacillus probiotics 1
Important Clinical Pearls
- Always obtain urine culture before starting antibiotics for complicated UTIs 1
- Replace indwelling catheters before collecting specimens if in place ≥2 weeks 1
- Do not treat asymptomatic bacteriuria in catheterized patients or most transplant recipients beyond 2 months post-transplant 1
- Immediate antimicrobial therapy is recommended rather than delayed treatment 7