What is the first-line treatment for an uncomplicated urinary tract infection (UTI)?

First-Line Treatment for Uncomplicated UTI

For uncomplicated urinary tract infections in women, use nitrofurantoin 100 mg twice daily for 5 days, fosfomycin 3 g single dose, or trimethoprim-sulfamethoxazole 160/800 mg twice daily for 3 days as first-line therapy. 1, 2

Treatment Selection Algorithm

Primary First-Line Options

• Nitrofurantoin macrocrystals: 50-100 mg four times daily for 5 days OR 100 mg twice daily for 5 days 1, 2

  • Minimal resistance patterns and low collateral damage to normal flora 2
  • Preferred when preserving gut microbiome is a priority

• Fosfomycin trometamol: 3 g single dose 1, 2

  • Convenient single-dose regimen with excellent patient compliance 2
  • Slightly lower efficacy than other first-line agents but acceptable for uncomplicated cases 2
  • Recommended only in women with uncomplicated cystitis 1

• Trimethoprim-sulfamethoxazole: 160/800 mg twice daily for 3 days 1, 2, 3

  • Critical caveat: Only use if local resistance rates are <20% OR if the infecting strain is known to be susceptible 2
  • Check your local antibiogram before prescribing empirically 2

Alternative First-Line Option

• Pivmecillinam: 400 mg twice daily for 5 days 2
  • Lower efficacy than other recommended agents 2
  • Avoid if early pyelonephritis is suspected 2

When Urine Culture Is NOT Needed

For typical uncomplicated cystitis in women with classic symptoms (dysuria, frequency, urgency) and no vaginal discharge, diagnosis can be made clinically without urine culture. 1, 4

When Urine Culture IS Required

Obtain urine culture and susceptibility testing in these situations: 1, 2

• Suspected acute pyelonephritis
• Symptoms that do not resolve or recur within 4 weeks after treatment completion
• Women presenting with atypical symptoms
• Pregnant women
• Treatment failure or recurrent infections
• History of resistant isolates 2

Non-Antibiotic Option for Mild Cases

For women with mild to moderate symptoms, symptomatic therapy with ibuprofen may be considered as an alternative to antimicrobials after discussing risks and benefits with the patient. 1, 2

• This approach recognizes that complications from untreated uncomplicated cystitis are low 4
• Delayed antibiotic prescriptions can be provided for symptom persistence 4

Common Pitfalls to Avoid

• Do NOT use fluoroquinolones as first-line therapy for uncomplicated cystitis—reserve these for complicated infections or pyelonephritis 1, 2
• Do NOT routinely perform post-treatment urinalysis or cultures in asymptomatic patients 1
• Do NOT treat asymptomatic bacteriuria except in pregnant women or before invasive urologic procedures 1, 2
• Do NOT assume trimethoprim-sulfamethoxazole will work without knowing local resistance patterns—many areas exceed 20% resistance 2

Treatment Failure Management

If symptoms persist by end of treatment or recur within 2 weeks: 1

• Obtain urine culture and antimicrobial susceptibility testing
• Assume the organism is NOT susceptible to the originally used agent
• Retreat with a 7-day regimen using a different antimicrobial class 1