What penicillin and/or ampicillin (beta-lactam antibiotic) drugs are included for Urinary Tract Infection (UTI) treatment?

Beta-Lactam Antibiotics for UTI Treatment

Amoxicillin-clavulanic acid is the only beta-lactam antibiotic recommended as a first-line treatment for lower urinary tract infections, while ampicillin is not recommended for empiric UTI treatment due to high resistance rates. 1

First-Line Beta-Lactam Options for UTIs

Lower UTI Treatment

• Amoxicillin-clavulanic acid - First-choice Access antibiotic for lower UTIs 1, 2
  • High susceptibility of E. coli to amoxicillin-clavulanic acid remains generally high in both adults and children 1
  • Recommended by the WHO Expert Committee as part of their AWaRe (Access, Watch, Reserve) classification 1

Upper UTI Treatment (Pyelonephritis)

• Ceftriaxone or cefotaxime - First-choice for severe pyelonephritis and prostatitis 1
  • For mild to moderate cases, these are considered second-choice options 1

Why Ampicillin Alone Is Not Recommended

• Plain ampicillin is not recommended for empiric UTI treatment due to high resistance rates:

  • 75% median resistance rate (range 45-100%) of E. coli urinary isolates to amoxicillin according to the 2020 Global Antimicrobial Resistance Surveillance System (GLASS) report 1
  • This high resistance has led multiple guidelines to discourage empiric use of amoxicillin for UTI treatment 1

• Ampicillin FDA label indicates it can be used for genitourinary tract infections caused by susceptible strains of E. coli, P. mirabilis, enterococci, and other specific organisms 3, but only when:

  • The infection is proven to be caused by susceptible bacteria
  • Culture and susceptibility testing confirm ampicillin sensitivity

Second-Line Beta-Lactam Options

• Oral cephalosporins such as cephalexin or cefixime can be considered as second-line options 4
• Amoxicillin-clavulanic acid can also be used as a second-line option in some cases 4
• For severe pyelonephritis requiring hospitalization, parenteral options include:
  • Extended-spectrum cephalosporins (e.g., ceftriaxone 1-2g daily) 2
  • Piperacillin/tazobactam for broader coverage 2
  • Ampicillin may be used in combination with aminoglycosides, but this was specifically excluded by the WHO Expert Committee for severe upper UTIs in children 1

Important Clinical Considerations

Resistance Patterns

• Decreasing susceptibility to ampicillin/sulbactam and third-generation cephalosporins has been observed in UTIs 5
• In one study, 55.1% of E. coli isolates were resistant to ampicillin and 32.7% to ampicillin-sulbactam 6
• The combination of clavulanic acid with amoxicillin significantly improves efficacy against penicillin-resistant bacteria (85% vs 25% cure rate) 7

Duration of Treatment

• 3-5 days for uncomplicated cystitis
• 7-14 days for complicated UTIs/pyelonephritis 2

Antibiotic Stewardship

• Beta-lactam antibiotics may promote more rapid recurrence of UTI compared to other antibiotics 1
• Regular monitoring of local resistance patterns is essential to guide empiric therapy 2
• Avoid overuse of broad-spectrum antibiotics to prevent further antimicrobial resistance 2

Conclusion

For UTI treatment, amoxicillin-clavulanic acid is the only beta-lactam antibiotic recommended as a first-line option for lower UTIs. Plain ampicillin or amoxicillin is no longer recommended for empiric treatment due to high resistance rates. For upper UTIs, ceftriaxone and cefotaxime are recommended, with ampicillin only considered in specific combination therapies when susceptibility is confirmed.