What are the first-line antibiotics for treating uncomplicated acute cystitis?

First-Line Antibiotics for Uncomplicated Acute Cystitis

Nitrofurantoin monohydrate/macrocrystals (100 mg twice daily for 5 days) is the recommended first-line therapy for uncomplicated acute cystitis due to minimal resistance patterns and limited collateral damage. 1, 2

First-Line Treatment Options

• Nitrofurantoin monohydrate/macrocrystals (100 mg twice daily for 5 days) is preferred first-line therapy with clinical cure rates of 88-93% and bacterial cure rates of 81-92% 2
• Trimethoprim-sulfamethoxazole (160/800 mg twice daily for 3 days) is appropriate first-line therapy only when local resistance rates are <20% or the infecting strain is confirmed susceptible 1, 2
• Fosfomycin trometamol (3 g single dose) is an appropriate option due to minimal resistance, though it may have slightly inferior efficacy compared to standard short-course regimens 1, 2
• Pivmecillinam (400 mg twice daily for 3-7 days) is recommended in regions where available (primarily European countries, not available in North America) 1, 3

Alternative Treatment Options

• Fluoroquinolones (ofloxacin, ciprofloxacin, levofloxacin) are highly effective in 3-day regimens but should be reserved as alternative agents due to their propensity for collateral damage (e.g., C. difficile infection, tendinopathy) 1, 3
• β-Lactam agents (amoxicillin-clavulanate, cefdinir, cefaclor, cefpodoxime-proxetil) in 3-7 day regimens should be used only when first-line agents cannot be used, as they generally have inferior efficacy and more adverse effects 1, 3
• Other β-lactams like cephalexin are less studied but may be appropriate in certain settings when other options are unavailable 1, 3

Treatments to Avoid

• Amoxicillin or ampicillin should not be used for empirical treatment due to poor efficacy and high prevalence of antimicrobial resistance worldwide 1, 2

Treatment Selection Considerations

• Local resistance patterns should guide the use of trimethoprim-sulfamethoxazole, which should only be used when local E. coli resistance is <20% 1, 2
• Nitrofurantoin has shown similar clinical cure rates to ciprofloxacin (93% vs 95%) and trimethoprim-sulfamethoxazole (93% vs 95%) 2
• Despite high efficacy, fluoroquinolones should be reserved for more serious infections due to concerns about increasing resistance and adverse effects 1, 4
• Amoxicillin-clavulanate has shown inferior efficacy compared to ciprofloxacin for uncomplicated cystitis, with clinical cure rates of 58% vs 77% 5

Treatment Duration

• Nitrofurantoin requires 5 days of treatment 1, 2
• Trimethoprim-sulfamethoxazole is effective with 3 days of treatment 1, 2
• Fosfomycin is administered as a single 3g dose 1, 2
• β-Lactams require 3-7 days of treatment when used 1, 2

Special Considerations

• For patients with mild renal insufficiency (CrCl 30-60 ml/min), nitrofurantoin can still be effective, though it is traditionally not recommended if CrCl <60 ml/min 6
• Nitrofurantoin should be avoided in patients with severe renal impairment (CrCl <30 ml/min) due to reduced efficacy 6
• Studies have shown low concordance with guidelines in primary care settings, with fluoroquinolones often overprescribed despite recommendations to reserve them as second-line agents 4