What antibiotics treat Escherichia coli (E. coli) in urine?

Antibiotics for E. coli Urinary Tract Infections

For uncomplicated E. coli urinary tract infections, first-line treatment options include amoxicillin-clavulanate, nitrofurantoin, and sulfamethoxazole-trimethoprim, with the choice depending on local resistance patterns. 1

First-Line Treatment Options for Lower UTIs

Adults with Uncomplicated UTI:

• Amoxicillin-clavulanate - First choice according to WHO guidelines 1
• Nitrofurantoin 100mg twice daily for 5 days 1, 2
• Sulfamethoxazole-trimethoprim 160/800mg twice daily for 3 days (if local resistance <20%) 1, 3

Important Considerations:

• Local resistance patterns should guide therapy - sulfamethoxazole-trimethoprim should only be used when local E. coli resistance is <20% 1
• Amoxicillin alone is no longer recommended due to high resistance rates (median 75% of E. coli urinary isolates resistant) 1
• Fosfomycin 3g single dose is an effective alternative with minimal resistance 2, 4

Treatment for Complicated UTIs/Pyelonephritis

Mild to Moderate Pyelonephritis:

• Ciprofloxacin (only if local resistance <10%) 1
• Ceftriaxone or cefotaxime (when fluoroquinolones cannot be used) 1

Severe Pyelonephritis:

• Ceftriaxone or cefotaxime (first choice) 1
• Amikacin (second choice, particularly for ESBL-producing strains) 1

Special Populations

Children:

• Amoxicillin-clavulanate or third-generation cephalosporins are most effective for febrile UTIs 5
• For severe infections: ceftazidime with ampicillin, or aminoglycoside with ampicillin 1

Pregnant Women:

• Nitrofurantoin (avoid in last trimester) or cephalosporins 2
• Fluoroquinolones are contraindicated 6

Treatment Duration

• Uncomplicated lower UTI: 3-5 days 2, 4
• Complicated UTI or pyelonephritis: 7-14 days 1, 2
• Men with UTI: 14 days (when prostatitis cannot be excluded) 1

Important Clinical Considerations

Antimicrobial Resistance:

• E. coli resistance to antibiotics is increasing globally 7
• Fluoroquinolones should not be used empirically if:
  • Local resistance rates exceed 10% 1
  • Patient has used fluoroquinolones in the last 6 months 1
  • Patient is from a urology department 1

Intracellular Bacteria:

• E. coli can form intracellular bacterial communities causing recurrent infections 8
• Ciprofloxacin, ceftriaxone, and azithromycin can reduce intracellular bacteria 8

Catheter-Associated UTIs:

• Replace indwelling catheter if present for ≥2 weeks 2
• Treatment follows complicated UTI guidelines 1

Algorithm for Antibiotic Selection

1. Obtain urine culture before starting antibiotics when possible 2
2. Assess severity (uncomplicated vs. complicated/pyelonephritis)
3. Check local resistance patterns for E. coli
4. Select appropriate antibiotic:
   • For uncomplicated UTI: amoxicillin-clavulanate, nitrofurantoin, or sulfamethoxazole-trimethoprim
   • For complicated UTI/pyelonephritis: parenteral therapy with ceftriaxone or ciprofloxacin (if resistance <10%)
5. Adjust therapy based on culture results and clinical response
6. Assess clinical response within 48-72 hours 2

Common Pitfalls to Avoid

• Using amoxicillin alone (high resistance rates) 1
• Using fluoroquinolones empirically when local resistance exceeds 10% 1
• Inadequate treatment duration, especially for complicated infections
• Failure to obtain cultures before starting antibiotics in complicated cases 2
• Not considering intracellular bacterial reservoirs in recurrent infections 8