What is the preferred antibiotic for treating a urinary tract infection (UTI) during the second trimester of pregnancy, ciprofloxacin (Cipro) or nitrofurantoin?

Nitrofurantoin is the Preferred Antibiotic for UTI in Second Trimester of Pregnancy

Nitrofurantoin should be used as the first-choice antibiotic for treating urinary tract infections during the second trimester of pregnancy, while ciprofloxacin should be avoided due to safety concerns and current guidelines. 1, 2

Rationale for Nitrofurantoin Use in Pregnancy

Nitrofurantoin is recommended as a first-choice option for treating lower urinary tract infections according to the most recent WHO Essential Medicines and AWaRe guidelines 1. This recommendation is supported by several key factors:

• High susceptibility rates of E. coli to nitrofurantoin in urinary isolates remain generally high 1
• Long history of safe use during pregnancy with no evidence of fetal toxicity 3
• Effective for treatment of asymptomatic bacteriuria and symptomatic UTIs in pregnancy 1
• Classified as an Access (A) antibiotic, indicating favorable risk-benefit profile 1

Why Ciprofloxacin Should Be Avoided

Ciprofloxacin is not recommended during pregnancy for UTIs for several important reasons:

• Classified as a Watch (W) antibiotic, indicating higher resistance potential 1
• FDA warnings about serious safety issues affecting tendons, muscles, joints, nerves, and central nervous system 1
• Potential risk for birth defects when used during pregnancy 4
• Reserved for more severe infections like pyelonephritis where benefits outweigh risks 1

Treatment Algorithm for UTI in Second Trimester

1. First-line therapy: Nitrofurantoin 100 mg orally twice daily for 7 days 1, 2

   • Highly effective against most uropathogens
   • Established safety profile in pregnancy
   • Low resistance rates

2. Alternative options (if nitrofurantoin contraindicated):

   • Amoxicillin-clavulanic acid 1, 2
   • Sulfamethoxazole-trimethoprim (avoid in first trimester and near term) 1
   • Cephalexin 4

3. For pyelonephritis or severe infection:

   • Hospitalization with IV ceftriaxone or cefotaxime 1, 2
   • Avoid ciprofloxacin unless absolutely necessary and other options are inappropriate 1

Clinical Considerations

• Treating UTIs during pregnancy is essential as untreated infections increase risk of pyelonephritis (20-30 fold), preterm delivery, and low birth weight 1
• Antimicrobial treatment decreases risk of subsequent pyelonephritis from 20-35% to 1-4% 1
• Follow-up urine culture 1-2 weeks after treatment completion is recommended to ensure cure 5
• Recurrent UTIs during pregnancy may benefit from prophylactic therapy 6

Common Pitfalls to Avoid

• Using ciprofloxacin as first-line therapy during pregnancy due to safety concerns
• Failing to treat asymptomatic bacteriuria during pregnancy, which increases risk of pyelonephritis
• Using nitrofurantoin for pyelonephritis (inadequate tissue penetration)
• Not obtaining follow-up cultures to confirm cure
• Using antibiotics with high resistance patterns (e.g., amoxicillin alone)

Nitrofurantoin has been used safely for over 35 years for UTI treatment in pregnancy with no evidence of fetal harm in retrospective analyses 7, 3. Its continued effectiveness against common uropathogens and favorable safety profile make it the clear choice over ciprofloxacin for UTI treatment during the second trimester of pregnancy.