What is the recommended treatment for a urinary tract infection (UTI) during the second trimester of pregnancy?

Treatment of UTI During Second Trimester of Pregnancy

The recommended first-line treatment for urinary tract infections during the second trimester of pregnancy is a 7-14 day course of a cephalosporin such as cephalexin, cefpodoxime, or cefuroxime. 1

Antibiotic Selection

• Cephalosporins (cephalexin, cefpodoxime, cefuroxime) are appropriate first-line options for treating UTIs during pregnancy as recommended by the American Academy of Pediatrics 1
• Nitrofurantoin is an acceptable option for uncomplicated lower UTIs, but should NOT be used for suspected pyelonephritis as it does not achieve therapeutic concentrations in the bloodstream 1
• Fosfomycin can be considered as an alternative treatment option for uncomplicated UTIs during pregnancy 1, 2
• Trimethoprim-sulfamethoxazole and fluoroquinolones should be avoided throughout pregnancy due to potential adverse effects on the fetus 1, 2

Treatment Duration and Approach

• The total course of therapy should be 7 to 14 days to ensure complete eradication of the infection 1
• A urine culture should be obtained before initiating treatment to guide antibiotic selection 1, 3
• Follow-up urine cultures should be performed 7 days after completing therapy to confirm cure 4
• For severe infections or pyelonephritis, initial parenteral therapy is required, with transition to oral therapy after clinical improvement 1, 3

Special Considerations

• Group B Streptococcus (GBS) bacteriuria in any concentration during pregnancy requires treatment at the time of diagnosis AND intrapartum GBS prophylaxis during labor 1
• Untreated asymptomatic bacteriuria can progress to acute pyelonephritis in up to 40% of pregnant women, with potential negative effects on both mother and fetus 5
• Bacteriuria in pregnancy is associated with higher rates of low birth weight, preterm delivery, and increased neonatal mortality 5, 3
• Escherichia coli is the most common pathogen isolated in UTIs during pregnancy 6

Management Algorithm

1. Obtain urine culture before starting antibiotics 1, 3
2. For uncomplicated UTI:
   • Start cephalexin 500 mg four times daily for 7-14 days 1
   • Alternative: nitrofurantoin 100 mg twice daily for 7 days (not for pyelonephritis) 1, 3
3. For pyelonephritis:
   • Hospitalize and start parenteral therapy with ceftriaxone or ampicillin plus gentamicin 1, 6
   • Transition to oral therapy after clinical improvement 1
   • Complete a total of 14 days of therapy 1
4. Perform follow-up urine culture 7 days after completing treatment 4

Common Pitfalls and Caveats

• Delaying treatment in pregnant women with symptomatic UTI increases the risk of pyelonephritis and adverse pregnancy outcomes 1
• Ampicillin should not be used as monotherapy due to high resistance rates in Escherichia coli 6
• Lower genital tract infections associated with pyelonephritis may be responsible for antibiotic treatment failure and should be evaluated 6
• Recurrent UTIs during pregnancy may require prophylactic antibiotics, though evidence for specific regimens is limited 3