Is Augmentin (amoxicillin-clavulanate) effective for treating urinary tract infections (UTIs)?

Augmentin for Urinary Tract Infections

Augmentin (amoxicillin-clavulanate) is an acceptable first-choice antibiotic for lower urinary tract infections (uncomplicated cystitis), but should NOT be used as first-line for upper UTIs (pyelonephritis) where other agents are preferred. 1

Lower Urinary Tract Infections (Uncomplicated Cystitis)

Augmentin is recommended as a first-choice option alongside nitrofurantoin and trimethoprim-sulfamethoxazole for treating lower UTIs. 1 The WHO Expert Committee specifically chose amoxicillin-clavulanate as one of three first-line Access antibiotics for this indication, noting that E. coli susceptibility to amoxicillin-clavulanate remains generally high in both adults and children. 1

Key Context on Amoxicillin vs. Augmentin

• Plain amoxicillin was removed from WHO recommendations in 2021 after global surveillance data showed a median of 75% (range 45-100%) of E. coli urinary isolates were resistant to amoxicillin alone. 1
• The addition of clavulanate overcomes beta-lactamase resistance, making Augmentin effective where plain amoxicillin fails. 1
• This distinction is critical: never use amoxicillin alone for UTIs, only the amoxicillin-clavulanate combination. 1

Dosing and Duration

• Standard adult dose: 875 mg/125 mg every 12 hours OR 500 mg/125 mg every 8 hours 2
• Duration: 3-5 days for uncomplicated cystitis in women 1
• Duration in men: 7 days (to account for possible occult prostatitis) 1
• FDA-approved data demonstrates comparable efficacy between the 875/125 mg twice-daily and 500/125 mg three-times-daily regimens for complicated UTIs. 2

Upper Urinary Tract Infections (Pyelonephritis)

For pyelonephritis, Augmentin is NOT a first-line choice. 1 The WHO guidelines recommend:

• Mild-to-moderate pyelonephritis: Ciprofloxacin (if local resistance <10%) OR ceftriaxone/cefotaxime 1
• Severe pyelonephritis: Ceftriaxone/cefotaxime as first choice, with amikacin as second choice 1

However, Augmentin demonstrated comparable bacteriologic efficacy in FDA trials for pyelonephritis, with cure rates of 81% at 2-4 days post-therapy and 52% at 2-4 weeks post-therapy. 2 This suggests it may be used when first-line agents are contraindicated or based on culture results.

Complicated UTIs

For complicated UTIs with systemic symptoms, Augmentin is NOT recommended as empiric monotherapy. 1 The European Association of Urology strongly recommends:

• Amoxicillin (without clavulanate) plus an aminoglycoside, OR
• A second-generation cephalosporin plus an aminoglycoside, OR
• An intravenous third-generation cephalosporin 1

The key distinction is that complicated UTIs require broader coverage or combination therapy, whereas Augmentin alone is insufficient for empiric treatment. 1

Important Caveats and Pitfalls

Resistance Considerations

• Always check local resistance patterns. The recommendation threshold is that local E. coli resistance should be <20% for empiric use in lower UTIs. 1
• Augmentin resistance can develop during treatment, particularly in patients with recurrent infections. 3
• Approximately 12-25% of urinary pathogens may show resistance or only moderate sensitivity to Augmentin. 3

Side Effects

• Diarrhea is the most common adverse effect (14-15% incidence), with severe diarrhea or treatment withdrawal occurring in 1-2% of patients. 2
• The 875/125 mg twice-daily regimen has statistically lower rates of severe diarrhea compared to the 500/125 mg three-times-daily regimen (1% vs 2%, p<0.05). 2
• Other reported side effects include abdominal pain, lightheadedness, and skin rash. 3
• Gastrointestinal side effects are generally mild and rarely require treatment discontinuation. 4, 5

Special Populations

• Pediatric dosing: 45 mg/kg/day divided every 12 hours for 10 days showed 87% cure rates for complicated infections. 2
• Recurrent UTIs: Historical data showed 84% microbiological cure at 1 week and 67% at 1 month in patients with recurrent infections. 4
• Renal insufficiency: Can be used in patients with chronic renal insufficiency (GFR 55-70 mL/min) with appropriate dose adjustment. 6

When to Avoid Augmentin

• Do NOT use for catheter-associated UTIs as empiric therapy 1
• Do NOT use as monotherapy for urosepsis or complicated UTIs with systemic symptoms 1
• Consider alternatives if patient has recent Augmentin exposure (<6 weeks) due to resistance risk 1
• Avoid if local E. coli resistance rates exceed 20% 1

Clinical Efficacy Data

Historical studies demonstrate 70% success rates for amoxicillin-resistant organisms when treated with Augmentin, and overall cure rates of 83-85% for uncomplicated UTIs. 7, 3, 6, 5 However, these older studies must be interpreted cautiously given evolving resistance patterns, which is why current guidelines emphasize checking local susceptibility data. 1