Treatment of a New Urinary Tract Infection
For a new urinary tract infection (UTI), first-line treatment should be nitrofurantoin, trimethoprim-sulfamethoxazole (TMP-SMX), or fosfomycin, with the specific choice depending on local antibiogram patterns. 1
Initial Assessment and Diagnosis
Before initiating treatment:
- Obtain urinalysis and urine culture with sensitivity prior to starting antibiotics 1
- Document symptoms (dysuria, frequency, urgency, hematuria)
- Consider patient-initiated treatment while awaiting culture results in select patients with recurrent UTIs 1
First-Line Treatment Options
| Antibiotic | Dosage | Duration | Comments |
|---|---|---|---|
| Nitrofurantoin | 100 mg twice daily | 5 days | Contraindicated in renal impairment |
| Fosfomycin trometamol | 3 g single dose | 1 day | Only for uncomplicated cystitis |
| TMP-SMX | 160/800 mg twice daily | 3 days | Avoid if local E. coli resistance >20% |
Treatment Duration
- Treat for as short a duration as reasonable, generally no longer than 7 days 1
- 5-day regimens for nitrofurantoin are recommended by current guidelines 1
- 3-day regimens for TMP-SMX are standard for uncomplicated UTIs 2
Special Considerations
For Resistant Organisms
- If cultures show resistance to oral antibiotics, consider culture-directed parenteral antibiotics for as short a course as reasonable (≤7 days) 1
- For complicated UTIs with multidrug-resistant organisms, options include:
- Ceftazidime-avibactam
- Meropenem-vaborbactam
- Imipenem-cilastatin-relebactam 1
For Recurrent UTIs
- Document positive urine cultures with prior symptomatic episodes 1
- Consider prophylactic strategies after treating the acute episode:
- Increased fluid intake
- Immunoactive prophylaxis
- Vaginal estrogen in postmenopausal women 1
Common Pitfalls to Avoid
- Do not treat asymptomatic bacteriuria unless in pregnancy 1
- Do not perform surveillance urine testing in asymptomatic patients with recurrent UTIs 1
- Avoid fluoroquinolones as first-line agents due to collateral damage to normal flora and increasing resistance 1
- Do not extend treatment duration unnecessarily as this increases risk of resistance 1
- Do not assume treatment failure if symptoms persist for 2-3 days; clinical improvement may take time 3
Follow-up
- Routine post-treatment urinalysis or cultures are not indicated for asymptomatic patients 1
- If symptoms do not resolve by end of treatment or recur within 2 weeks:
- Obtain urine culture and sensitivity
- Assume the organism is not susceptible to the original agent
- Retreat with a 7-day regimen using another agent 1
By following these evidence-based guidelines, you can effectively treat a new UTI while practicing good antimicrobial stewardship to minimize resistance development.