Augmentin for Urinary Tract Infections
Augmentin (amoxicillin-clavulanate) is effective for uncomplicated lower urinary tract infections (cystitis) in women when local E. coli resistance rates are below 20%, but it should NOT be used as empiric monotherapy for complicated UTIs with systemic symptoms, pyelonephritis, or catheter-associated UTIs. 1
Appropriate Use for Lower UTIs (Uncomplicated Cystitis)
Augmentin is a WHO-recommended first-choice option for uncomplicated lower UTIs, alongside nitrofurantoin and trimethoprim-sulfamethoxazole, with generally high E. coli susceptibility maintained globally 1. The key advantage is that clavulanate overcomes beta-lactamase resistance, making it effective where plain amoxicillin fails—never use amoxicillin alone for UTIs, only the combination formulation 1.
Dosing and Duration
- For women with uncomplicated cystitis: Treat for 3-5 days 1
- For men with uncomplicated cystitis: Treat for 7 days to account for possible occult prostatitis 1
- Standard dosing is 875 mg/125 mg every 12 hours or 500 mg/125 mg every 8 hours 2
Critical Resistance Threshold
Check local E. coli resistance patterns before prescribing—do not use empirically if local resistance exceeds 20% 1. This threshold is based on expert consensus from clinical and modeling studies 3. Additionally, avoid Augmentin if the patient has had recent exposure within the past 6 weeks due to increased resistance risk 1.
When NOT to Use Augmentin
Complicated UTIs with Systemic Symptoms
The European Association of Urology explicitly recommends AGAINST using Augmentin as empiric monotherapy for complicated UTIs with systemic symptoms 3, 1. Instead, use combination therapy:
- Amoxicillin plus an aminoglycoside (strong recommendation) 3
- Second-generation cephalosporin plus an aminoglycoside (strong recommendation) 3
- Intravenous third-generation cephalosporin as empirical treatment (strong recommendation) 3
Pyelonephritis (Upper UTI)
Augmentin is NOT a first-line choice for pyelonephritis 1. The WHO guidelines recommend:
- Mild-to-moderate pyelonephritis: Ciprofloxacin or ceftriaxone/cefotaxime 1
- Severe pyelonephritis: Ceftriaxone/cefotaxime as first choice, with amikacin as second choice 1
The FDA label confirms Augmentin's use in complicated UTIs including pyelonephritis, but guideline recommendations prioritize other agents for upper tract infections 2.
Catheter-Associated UTIs
Do not use Augmentin as empiric therapy for catheter-associated UTIs 1. These infections require broader coverage given the higher likelihood of resistant organisms and polymicrobial infection 3.
Urosepsis
Augmentin should not be used as monotherapy for urosepsis 1. Patients with life-threatening organ dysfunction require aggressive combination therapy as outlined for complicated UTIs with systemic symptoms 3.
Clinical Efficacy Data
The FDA label demonstrates comparable efficacy between 875 mg/125 mg every 12 hours and 500 mg/125 mg every 8 hours regimens for complicated UTIs, with bacteriologic success rates of 81% at 2-4 days post-therapy, 58% at 5-9 days, and 52% at 2-4 weeks 2. However, there was a statistically significant difference in severe diarrhea rates: 1% for the every-12-hour regimen versus 2% for the every-8-hour regimen 2.
Older research studies from the 1980s showed microbiological cure rates of 84% at 1 week and 67% at 1 month for recurrent UTIs 4, with success rates around 70% for amoxicillin-resistant organisms 5. However, these studies predate current resistance patterns and should be interpreted cautiously.
Common Pitfalls to Avoid
- Never prescribe plain amoxicillin for UTIs—only the amoxicillin-clavulanate combination overcomes beta-lactamase resistance 1
- Do not assume Augmentin is appropriate for all UTIs—it is specifically for uncomplicated lower UTIs only 1
- Always obtain urine culture and susceptibility testing for complicated UTIs before initiating therapy, and tailor treatment accordingly 3
- Avoid empiric use in patients from urology departments or those with recent antibiotic exposure, as resistance rates are higher 3
- Monitor for diarrhea, which occurs in approximately 15% of patients and is the most common adverse effect 2