What are the recommended antibiotics for treating urinary tract infections (UTIs) in pregnancy?

Recommended Antibiotics for UTIs in Pregnancy

Nitrofurantoin is the first-line antibiotic treatment for urinary tract infections in pregnancy, with a recommended dosage of 50-100mg four times daily for 5-7 days. 1

First-Line Treatment Options

• Nitrofurantoin (50-100mg four times daily for 5-7 days)

  • Preferred due to its safety profile in pregnancy, low resistance rates, and quick decay of resistance 1, 2
  • Contraindicated in G6PD deficiency and near term (>36 weeks) due to risk of hemolytic anemia in the newborn
  • Not recommended in pyelonephritis due to poor tissue penetration

• Fosfomycin trometamol (3g single dose)

  • Alternative first-line option with comparable efficacy to nitrofurantoin 1, 3
  • Convenient single-dose administration
  • Good safety profile in pregnancy

Second-Line Treatment Options

• Amoxicillin-clavulanate (500/125mg three times daily for 5-7 days)

  • Effective against beta-lactamase-producing E. coli, Klebsiella species, and Enterobacter species 4
  • Higher risk of gastrointestinal side effects
  • Use when first-line options are contraindicated or ineffective

• Cephalexin (250-500mg four times daily for 5-7 days)

  • Safe in pregnancy
  • Effective for susceptible organisms
  • Consider when first-line options are contraindicated

Special Considerations

Asymptomatic Bacteriuria

• All pregnant women should be screened for asymptomatic bacteriuria with urine culture at least once in early pregnancy 5, 1
• Treatment of asymptomatic bacteriuria in pregnancy is recommended to prevent pyelonephritis and reduce the risk of preterm birth and low birth weight 5, 6

Recurrent UTIs in Pregnancy

• For women with history of recurrent UTIs during pregnancy, post-coital prophylaxis is highly effective:
  • Cephalexin 250mg or Nitrofurantoin macrocrystals 50mg as a single dose within 2 hours after intercourse 1, 7
  • This approach has shown significant reduction in UTI recurrence during pregnancy 7

Pyelonephritis

• Requires hospitalization and IV antibiotics initially
• Second and third-generation cephalosporins are recommended 6
• Switch to oral therapy once clinically improved

Treatment Algorithm

1. Obtain urine culture before initiating treatment

   • Essential for confirming diagnosis and guiding therapy

2. Select appropriate antibiotic based on:

   • Trimester of pregnancy
   • Patient allergies
   • Local resistance patterns
   • Previous culture results if available

3. First-line empiric therapy:

   • Nitrofurantoin 50-100mg four times daily for 5-7 days (if <36 weeks gestation)
   • Fosfomycin 3g single dose (alternative first-line)

4. Second-line options (if first-line contraindicated or ineffective):

   • Amoxicillin-clavulanate 500/125mg three times daily for 5-7 days
   • Cephalexin 250-500mg four times daily for 5-7 days

5. Follow-up culture 1-2 weeks after treatment completion

   • To confirm eradication of bacteriuria

Common Pitfalls to Avoid

• Using fluoroquinolones or tetracyclines, which are contraindicated in pregnancy
• Treating asymptomatic bacteriuria outside of pregnancy (except in pregnancy, screening and treatment is recommended) 5
• Using trimethoprim-sulfamethoxazole in the first trimester (risk of neural tube defects) or near term (risk of kernicterus)
• Failing to obtain follow-up cultures after treatment
• Using nitrofurantoin after 36 weeks gestation or in G6PD deficiency
• Inadequate duration of therapy (shorter courses have lower cure rates in pregnancy) 5

By following these evidence-based recommendations, UTIs in pregnancy can be effectively managed while minimizing risks to both mother and fetus.