What is the recommended medical management for an otherwise healthy adult woman with acute cystitis?

Medical Management of Acute Uncomplicated Cystitis in Adult Women

Nitrofurantoin monohydrate/macrocrystals 100 mg twice daily for 5 days is the preferred first-line treatment for acute uncomplicated cystitis in otherwise healthy adult women, offering clinical cure rates of 88-93% with minimal resistance and limited collateral damage to normal flora. 1, 2

First-Line Treatment Options

The choice of empiric therapy depends critically on local resistance patterns and patient-specific factors:

Nitrofurantoin (Preferred First-Line)

• Nitrofurantoin monohydrate/macrocrystals 100 mg twice daily for 5 days is the optimal first-line choice due to minimal resistance (<10% in most regions) and limited ecological damage 1, 2
• Achieves clinical cure rates of 88-93% and bacterial cure rates of 81-92% 2
• Avoid if early pyelonephritis is suspected (fever, flank pain, systemic symptoms), as nitrofurantoin does not achieve adequate tissue levels in the kidney 1

Trimethoprim-Sulfamethoxazole (Conditional First-Line)

• Trimethoprim-sulfamethoxazole 160/800 mg (one double-strength tablet) twice daily for 3 days is appropriate only when local E. coli resistance is documented to be <20% 1, 2, 3
• Clinical cure rates are 90-100% for susceptible organisms but plummet to 41-54% when organisms are resistant 2, 3
• Avoid if the patient used this antibiotic for UTI in the preceding 3 months or has traveled outside the United States in the preceding 3-6 months, as these factors independently predict resistance 3
• The 20% resistance threshold is based on expert opinion from clinical, in vitro, and mathematical modeling studies showing that treatment failures outweigh benefits above this level 1, 3

Fosfomycin (Alternative First-Line)

• Fosfomycin trometamol 3 g as a single oral dose offers the convenience of single-dose therapy with clinical cure rates of approximately 90% 1, 2
• Microbiological cure rates may be slightly lower (78%) compared to nitrofurantoin (86%) 2
• Avoid if early pyelonephritis is suspected 1

Second-Line Treatment Options (When First-Line Agents Cannot Be Used)

Fluoroquinolones (Reserve for Specific Situations)

• Ciprofloxacin 250 mg twice daily for 3 days or levofloxacin 500 mg once daily for 3 days achieve bacteriologic eradication rates of 93-97% 3, 4
• Should be reserved as alternative agents due to their propensity for collateral damage (promoting resistance in normal flora and other pathogens) and the need to preserve these agents for more serious infections like pyelonephritis 1, 2, 3
• Resistance prevalence is increasing in some geographic areas, making them less reliable for empiric use 1

Beta-Lactam Agents (Least Preferred)

• Amoxicillin-clavulanate, cefdinir, cefaclor, or cefpodoxime-proxetil for 3-7 days should be used only when first-line agents cannot be used 2
• These agents generally have inferior efficacy and more adverse effects compared to first-line options 2
• Never use amoxicillin or ampicillin alone due to poor efficacy and high worldwide resistance rates (>30% in most regions) 2

Critical Clinical Pitfalls to Avoid

• Do not use short-course regimens (3-5 days) in men—male cystitis requires 7-14 days of therapy due to potential prostatic involvement 5
• Do not prescribe trimethoprim-sulfamethoxazole empirically without knowing local resistance rates—hospital antibiograms often overestimate community resistance, so seek outpatient surveillance data 3
• Do not use fluoroquinolones as routine first-line therapy despite their high efficacy, as this promotes resistance to agents needed for pyelonephritis and other serious infections 2, 3
• Do not use nitrofurantoin or fosfomycin if pyelonephritis is suspected (presence of fever >38°C, flank pain, costovertebral angle tenderness, nausea/vomiting), as these agents do not achieve adequate renal tissue levels 1

Treatment Algorithm for Patients with Allergies

Sulfa Allergy

• Use nitrofurantoin 100 mg twice daily for 5 days as first-line 2
• Alternative: fosfomycin 3 g single dose 2
• If both unavailable: fluoroquinolone for 3 days (ciprofloxacin 250 mg twice daily or levofloxacin 500 mg once daily) 2

Penicillin Allergy (without cephalosporin cross-reactivity)

• Use nitrofurantoin or trimethoprim-sulfamethoxazole (if resistance <20%) 2
• Certain cephalosporins (cefdinir, cefpodoxime) may be considered if no cross-reactivity history 2

Both Sulfa and Penicillin Allergies

• Fosfomycin 3 g single dose is the preferred alternative first-line option 2
• If unavailable: fluoroquinolone for 3 days 2

Expected Clinical Response

• Symptoms should improve within 48-72 hours of initiating appropriate therapy 5
• If symptoms persist or worsen, obtain urine culture with susceptibility testing to guide targeted therapy 5
• Each additional day of antibiotic treatment beyond the recommended duration carries a 5% increased risk for antibiotic-associated adverse events without additional clinical benefit 3