What are the recommended antibiotics (Abx) for an uncomplicated urinary tract infection (UTI) in an otherwise healthy adult?

Recommended Antibiotics for Uncomplicated UTI in Adults

For uncomplicated urinary tract infections in otherwise healthy adults, nitrofurantoin 100 mg twice daily for 5 days is the preferred first-line treatment. 1, 2

First-Line Treatment Options

The choice among first-line agents depends on local resistance patterns and patient-specific factors:

Nitrofurantoin (Preferred)

• Nitrofurantoin 100 mg twice daily for 5 days is the optimal first-line choice for uncomplicated cystitis in women 1, 2
• This agent produces minimal "collateral damage" to normal flora compared to broader-spectrum antibiotics and helps preserve fluoroquinolones for more serious infections 2
• The WHO recommends nitrofurantoin as first-choice treatment for lower UTIs 2
• Treatment duration should not exceed 7 days for acute cystitis 2

Trimethoprim-Sulfamethoxazole (TMP-SMX)

• TMP-SMX 160/800 mg twice daily for 3 days is an appropriate alternative only if local E. coli resistance rates are below 20% 1, 3
• Rising resistance rates have necessitated revising previous recommendations that made this a universal first-line agent 1, 2
• Studies show nitrofurantoin has lower treatment failure rates compared to TMP-SMX in areas with higher resistance 2

Fosfomycin

• Fosfomycin 3 g as a single oral dose is another first-line option 1, 4
• While convenient as single-dose therapy, it may have slightly inferior efficacy compared to standard short-course regimens 2
• Must be mixed with water before ingesting; never take in dry form 4

Second-Line and Alternative Agents

Fluoroquinolones (Reserve for Specific Situations)

• Fluoroquinolones (ciprofloxacin, levofloxacin) should NOT be used as first-line agents for uncomplicated cystitis 1, 2
• These are highly efficacious in 3-day regimens but have significant propensity for "collateral damage" and serious adverse effects 1
• The FDA has issued warnings about serious safety issues affecting tendons, muscles, joints, nerves, and the central nervous system 2
• Reserve fluoroquinolones for pyelonephritis or patients with documented resistance to first-line agents 2

β-Lactam Agents (Use with Caution)

• β-lactams including amoxicillin-clavulanate, cefdinir, cefaclor, and cefpodoxime-proxetil are appropriate only when first-line agents cannot be used 1
• These agents generally have inferior efficacy and more adverse effects compared to first-line options 1
• Treatment duration is 3-7 days when used 1
• Amoxicillin or ampicillin alone should NEVER be used empirically due to poor efficacy and very high worldwide resistance rates 1

Treatment Duration by Agent

• Nitrofurantoin: 5 days 1, 2
• TMP-SMX: 3 days 1, 3
• Fosfomycin: Single dose 1, 4
• Fluoroquinolones (if used): 3 days for cystitis 1
• β-lactams (if used): 3-7 days 1

Special Considerations and Important Caveats

When NOT to Use Nitrofurantoin

• Do not use nitrofurantoin for pyelonephritis (fever, flank pain, systemic symptoms) as it does not achieve adequate tissue concentrations 2
• Avoid in patients with creatinine clearance <60 mL/min 2
• Contraindicated in infants under 4 months of age 2

Diagnostic Approach

• Urine culture is NOT necessary before starting empiric therapy in uncomplicated UTIs 2
• In women, self-diagnosis with typical symptoms (frequency, urgency, dysuria, nocturia, suprapubic pain) without vaginal discharge is accurate enough to diagnose and treat without testing 5
• Reserve urine culture for: recurrent infections, treatment failure, history of resistant organisms, or atypical presentation 2, 5

Men with UTI

• Men should always receive antibiotics and require urine culture with susceptibility testing 5
• First-line options include trimethoprim, TMP-SMX, or nitrofurantoin for 7 days (longer than women) 5
• Consider urethritis and prostatitis in the differential diagnosis 5

Resistance Considerations

• Check local antibiogram data before selecting empiric therapy 1, 2
• Local resistance patterns vary considerably between regions and should guide treatment choices 2
• If local E. coli resistance to nitrofurantoin exceeds 10%, consider alternative treatments 2

Common Pitfalls to Avoid

• Do not treat asymptomatic bacteriuria except in pregnancy or before urologic procedures 2
• Do not use fluoroquinolones as first-line therapy despite their high efficacy—reserve them for complicated infections 1, 2
• Do not prescribe amoxicillin or ampicillin alone for empiric treatment 1
• Do not exceed 7 days of treatment for uncomplicated cystitis 1, 2
• Do not order surveillance urine testing in asymptomatic patients with recurrent UTIs 2