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

Recommended Antibiotics for UTI in Pregnancy

For urinary tract infections during pregnancy, the recommended first-line antibiotics are nitrofurantoin, fosfomycin, and cephalexin (such as cefixime), as these provide effective treatment while maintaining safety for both mother and fetus. 1

First-Line Treatment Options

• Nitrofurantoin: 100 mg twice daily for 5 days

  • Safe and effective during pregnancy
  • Should be avoided near term (>36 weeks) due to risk of hemolytic anemia in newborns
  • Contraindicated in G6PD deficiency

• Fosfomycin: 3 g single dose

  • Convenient single-dose regimen
  • Good safety profile in pregnancy
  • Effective against many resistant pathogens

• Cephalexin/Cefixime: Cephalexin 500 mg four times daily for 5-7 days

  • Cefixime appears particularly effective against common uropathogens (E. coli)
  • High safety profile in pregnancy 2
  • Low resistance rates compared to ampicillin

Second-Line Options

• Amoxicillin-clavulanic acid: Recommended by WHO as a first-choice for lower UTIs 1
  • May be used when first-line agents are contraindicated
  • Dosing: 500/125 mg three times daily for 5-7 days

Duration of Therapy

• Uncomplicated UTI: 5-7 days of therapy is generally recommended 3

  • Single-dose therapy (except for fosfomycin) is less effective than short-course therapy
  • 3-day regimens may be insufficient for complete resolution in pregnancy

• Complicated UTI/Pyelonephritis: 7-14 days of therapy 1

  • May require initial parenteral therapy if severe

Important Clinical Considerations

• Always obtain urine culture before starting antibiotics to confirm the causative pathogen and determine susceptibility 1

• Consider local resistance patterns when selecting empiric therapy

  • Trimethoprim-sulfamethoxazole (TMP-SMX) should be avoided in the first trimester due to potential teratogenic effects and in the third trimester due to risk of neonatal hyperbilirubinemia

• Asymptomatic bacteriuria should be treated in pregnancy unlike in other populations 3

  • Untreated ASB in pregnancy increases risk of pyelonephritis, preterm birth, and low birth weight

• Avoid fluoroquinolones due to potential adverse effects on fetal cartilage development 1, 4

• Avoid ampicillin as empiric therapy due to high resistance rates worldwide 1, 4

Management Algorithm

1. Diagnosis: Confirm UTI through symptoms and urinalysis/culture
2. Initial therapy: Select from first-line agents based on:
   • Patient allergies
   • Previous culture results (if available)
   • Local resistance patterns
3. Follow-up: Repeat urine culture 1 week after completing therapy to confirm cure
4. Recurrent UTIs: Consider prophylaxis with:
   • Nitrofurantoin 50-100 mg daily
   • Cephalexin 250 mg post-coital dose 5

Pitfalls to Avoid

• Don't delay treatment while waiting for culture results in symptomatic patients
• Don't treat asymptomatic bacteriuria differently than symptomatic UTI in pregnancy
• Don't forget to adjust therapy based on culture results when available
• Don't use fluoroquinolones or TMP-SMX as first-line agents in pregnancy
• Don't fail to follow up with repeat cultures after treatment

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