What is the recommended treatment for a urinary tract infection (UTI) in pregnant women?

Treatment of Urinary Tract Infections in Pregnant Women

First-line treatment for urinary tract infections (UTIs) in pregnant women includes nitrofurantoin, fosfomycin trometamol, or pivmecillinam, with trimethoprim-sulfamethoxazole as an option in early pregnancy when resistance rates are low. 1

Diagnosis and Screening

• All pregnant women should be screened for bacteriuria by urine culture at least once in early pregnancy (typically at 12-16 weeks) 1
• Any quantity of bacteriuria during pregnancy requires treatment, as untreated bacteriuria can lead to pyelonephritis in 20-37% of cases 1
• Obtain urine culture before initiating treatment to guide antibiotic selection 1

Treatment Options

First-line antibiotics for UTI in pregnancy:

1. Nitrofurantoin (100 mg twice daily for 5-7 days)

   • Long safety record in pregnancy 2
   • Avoid near term (>36 weeks) due to risk of hemolytic anemia in newborns
   • Contraindicated in G6PD deficiency

2. Fosfomycin trometamol (3g single dose)

   • Convenient single-dose regimen
   • Comparable efficacy to nitrofurantoin 3
   • Safe in pregnancy with minimal systemic absorption

3. Pivmecillinam (400 mg twice daily for 3-7 days)

   • Good safety profile in pregnancy
   • Effective against most uropathogens

4. Trimethoprim-sulfamethoxazole (160/800 mg twice daily for 3 days)

   • Use only when local resistance rates are <20% 4
   • Avoid in first trimester (risk of neural tube defects) and near term (risk of kernicterus)

Management Algorithm

1. For asymptomatic bacteriuria:

   • Treat with any of the above antibiotics
   • Single-dose therapy with fosfomycin is appropriate 3
   • Follow-up urine culture 1-2 weeks after treatment 1

2. For uncomplicated cystitis:

   • Nitrofurantoin for 5 days OR
   • Fosfomycin as single dose OR
   • Pivmecillinam for 5 days 1, 4
   • Follow-up culture to confirm cure

3. For pyelonephritis:

   • Hospitalization and IV antibiotics are indicated 4
   • Third-generation cephalosporins are preferred 4
   • Switch to oral antibiotics when clinically improved
   • Total treatment duration: 10-14 days

Prevention Strategies

• Increased fluid intake (strong evidence for prevention) 1
• Urinating before and after sexual activity 1
• Proper wiping technique (front to back) 1
• Avoiding irritating feminine products 1

Follow-up

• Obtain follow-up urine culture 1-2 weeks after completing treatment to confirm cure 1
• Some experts recommend continuous antimicrobial prophylaxis until delivery for women with recurrent UTIs during pregnancy 1

Important Considerations

• Escherichia coli is the most common pathogen in pregnancy-associated UTIs 4, 5
• Treatment of asymptomatic bacteriuria decreases rates of pyelonephritis from 20-37% to 1-6% 1
• Avoid fluoroquinolones and tetracyclines during pregnancy due to potential fetal risks
• Older studies suggested amoxicillin as an option, but increasing resistance rates limit its current utility 6

Pitfalls to Avoid

• Failing to screen for asymptomatic bacteriuria in pregnancy
• Undertreating UTIs in pregnancy (can lead to pyelonephritis and preterm labor)
• Using antibiotics contraindicated in pregnancy
• Not obtaining follow-up cultures to confirm cure
• Misdiagnosing asymptomatic bacteriuria as symptomatic UTI, leading to unnecessary antibiotic exposure 4