What is the treatment for a urinary tract infection (UTI) in pregnancy?

Treatment of Urinary Tract Infections in Pregnancy

For pregnant women with UTIs, first-line treatment should be nitrofurantoin, fosfomycin, or cephalosporins, with treatment duration of 5-7 days for symptomatic infections and antibiotic selection based on local resistance patterns. 1, 2

Classification of UTIs in Pregnancy

UTIs in pregnancy can be classified as:

1. Asymptomatic bacteriuria (ASB): Presence of bacteria in urine without symptoms
2. Cystitis: Lower UTI with symptoms (dysuria, frequency, urgency)
3. Pyelonephritis: Upper UTI with systemic symptoms (fever, flank pain, nausea/vomiting)

Unlike non-pregnant women, ALL forms of UTI in pregnancy require treatment, including asymptomatic bacteriuria, due to increased risks of maternal and fetal complications 3.

Diagnostic Approach

• Obtain a midstream urine sample for culture before initiating antibiotics
• Positive culture is defined as ≥105 CFU/mL of a single uropathogen
• Pregnant women should be screened for asymptomatic bacteriuria at their first prenatal visit 1

First-Line Treatment Options

For Asymptomatic Bacteriuria and Cystitis:

Antibiotic	Dosage	Duration
Nitrofurantoin	100 mg twice daily	5 days
Fosfomycin trometamol	3 g single dose	1 day
Cephalexin	500 mg four times daily	5-7 days
Amoxicillin-clavulanate	500 mg three times daily	5-7 days

For Pyelonephritis:

• Initial parenteral therapy until clinically improved (24-48 hours)
• Options include ceftriaxone, cefotaxime, or gentamicin
• Then transition to oral therapy to complete 7-14 days total

Important Considerations

1. Avoid these antibiotics during pregnancy:

   • Fluoroquinolones (contraindicated)
   • Trimethoprim in first trimester (folate antagonist)
   • Sulfonamides in third trimester (risk of kernicterus)
   • Tetracyclines (dental staining)

2. Follow-up cultures:

   • Obtain a test-of-cure urine culture 1-2 weeks after completing therapy
   • Monthly urine cultures should be performed throughout pregnancy after treatment 1

3. Antibiotic stewardship:

   • Choose antibiotics based on local resistance patterns
   • Use narrow-spectrum agents when possible
   • Avoid fluoroquinolones and cephalosporins when alternatives are available to minimize collateral damage to gut flora 1

Special Situations

Recurrent UTIs in Pregnancy

For women with recurrent UTIs during pregnancy:

• Consider antibiotic prophylaxis after treatment of acute episode
• Options include nitrofurantoin 100 mg daily or cephalexin 250 mg daily
• Continue prophylaxis for duration of pregnancy 1

GBS Bacteriuria

• Any concentration of Group B Streptococcus in urine during pregnancy requires treatment
• Women with GBS bacteriuria should receive intrapartum antibiotic prophylaxis regardless of subsequent screening results 1

Pitfalls and Caveats

1. Do not treat asymptomatic bacteriuria in non-pregnant women, but DO treat it in pregnant women due to risk of pyelonephritis and adverse pregnancy outcomes 1, 3

2. Avoid nitrofurantoin near term (>36 weeks) due to potential risk of neonatal hemolytic anemia

3. Do not use agents that only achieve urinary concentrations (like nitrofurantoin) for treatment of pyelonephritis, as they won't reach therapeutic levels in the kidney parenchyma 1

4. Ensure adequate follow-up - UTIs in pregnancy have high recurrence rates and can lead to complications including preterm birth and low birth weight if not properly treated and monitored 3

5. Consider local resistance patterns when selecting empiric therapy, as resistance to common antibiotics varies significantly by region 1, 4

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