What is the first line treatment for acute uncomplicated cystitis?

First-Line Treatment for Acute Uncomplicated Cystitis

The first-line treatment for acute uncomplicated cystitis is nitrofurantoin monohydrate/macrocrystals 100 mg twice daily for 5 days. 1

Treatment Algorithm

1. First-line options (in order of preference):

   • Nitrofurantoin monohydrate/macrocrystals: 100 mg twice daily for 5 days 1
   • Trimethoprim-sulfamethoxazole: 160/800 mg (1 double-strength tablet) twice daily for 3 days (only when local resistance rates are below 20%) 1
   • Fosfomycin trometamol: 3 g single dose 1, 2

2. Alternative options (when first-line agents are contraindicated):

   • Trimethoprim: 100 mg twice daily for 3 days 1
   • Fluoroquinolones (should be reserved as alternatives due to resistance concerns)

Evidence-Based Rationale

The Infectious Diseases Society of America (IDSA) and European Society for Microbiology and Infectious Diseases recommend nitrofurantoin as a first-line agent for uncomplicated cystitis 1. This recommendation is supported by clinical evidence showing high efficacy rates with a 5-day course.

Trimethoprim-sulfamethoxazole (TMP-SMX) is also effective but should only be used when local resistance rates are below 20% and the patient has no history of recent TMP-SMX use or international travel 1. A 3-day course is sufficient for uncomplicated cystitis.

Fosfomycin trometamol (3g single dose) offers convenience but has shown lower microbiological eradication rates (82%) compared to ciprofloxacin (98%) and TMP-SMX (98%) in clinical studies 2. However, it was found to be equivalent to nitrofurantoin in terms of efficacy 2.

Special Considerations

• Resistance patterns: Local antibiotic resistance patterns should guide therapy. TMP-SMX should be avoided if local E. coli resistance exceeds 20% 1.
• Pregnancy: Nitrofurantoin can be used in pregnant women with normal renal function but should be avoided in the third trimester due to risk of hemolytic anemia in newborns 1.
• Renal impairment: Nitrofurantoin should be avoided in patients with GFR <30 ml/min 1.
• Follow-up: No routine follow-up urine culture is needed in patients who respond to therapy 1.

Common Pitfalls to Avoid

1. Treating asymptomatic bacteriuria: This increases antibiotic resistance without clinical benefit 1.
2. Prolonged treatment courses: These increase the risk of side effects and resistance without improving outcomes 1.
3. Using fluoroquinolones as first-line: These should be reserved for situations where first-line agents cannot be used, to prevent development of resistance.
4. Failure to obtain urine culture before treatment: This is particularly important in recurrent cases to guide therapy 1.
5. Overlooking local resistance patterns: Local E. coli resistance to TMP-SMX may exceed 20% in many regions, making it a less suitable first-line option 1, 3.

Treatment Efficacy

A study comparing nitrofurantoin (5-day course) with TMP-SMX (3-day course) found equivalent clinical and microbiological cure rates 4. Nitrofurantoin achieved clinical cure in 84% of patients compared to 79% for TMP-SMX 4. Importantly, nitrofurantoin maintained efficacy regardless of pathogen susceptibility patterns, while TMP-SMX efficacy dropped significantly (to 41%) against TMP-SMX-resistant isolates 4.

Fosfomycin's single-dose convenience must be balanced against its slightly lower microbiological eradication rates compared to longer courses of other antibiotics 2.