What is the recommended treatment for Group B strep (Streptococcus agalactiae) urinary tract infection during the first trimester of pregnancy?

Treatment of Group B Streptococcus UTI in First Trimester of Pregnancy

Group B Streptococcus urinary tract infection during the first trimester of pregnancy requires immediate treatment regardless of colony count, following standard UTI treatment protocols with pregnancy-safe antibiotics. 1

Immediate Treatment Approach

• All GBS isolates from urine should be treated regardless of colony count (even <100,000 CFU/mL), as GBS bacteriuria is a marker for heavy genital tract colonization 1, 2
• Treatment should follow current standards of care for UTI during pregnancy, using antibiotics that are safe during the first trimester 1
• Appropriate first-line antibiotics include:
  • Penicillin or ampicillin (preferred due to narrow spectrum) 3, 1
  • First-generation cephalosporins for those without severe penicillin allergy 1, 2
  • For penicillin-allergic patients with high risk of anaphylaxis, treatment should be guided by susceptibility testing to clindamycin and erythromycin 3

Follow-up Management

• After treatment of the acute UTI, no repeat urine cultures are necessary to document clearance 2
• Women with GBS bacteriuria at any point during pregnancy should not be re-screened by genital tract culture or urinary culture in the third trimester, as they are presumed to be GBS colonized 1, 2
• All women with documented GBS bacteriuria during the current pregnancy must receive intrapartum antibiotic prophylaxis during labor to prevent early-onset neonatal GBS disease 1, 2
• These women do not need additional GBS screening at 35-37 weeks' gestation 1, 3

Intrapartum Prophylaxis Regimens

• For women without penicillin allergy:

  • Penicillin G: 5 million units IV initial dose, then 2.5 million units IV every 4 hours until delivery (preferred) 3
  • Alternative: Ampicillin, 2g IV initial dose, then 1g IV every 4 hours until delivery 3

• For women with penicillin allergy without anaphylaxis history:

  • Cefazolin: 2g IV initial dose, then 1g IV every 8 hours until delivery 3

• For women with high risk for anaphylaxis:

  • Clindamycin or erythromycin based on susceptibility testing 3
  • If susceptibility unknown or resistance present, vancomycin may be used 1

Common Pitfalls and Caveats

• Attempting to eradicate GBS colonization before labor with antibiotics beyond treating the acute UTI is ineffective and may cause adverse consequences 1, 3
• Withholding intrapartum prophylaxis for women with history of GBS bacteriuria in the current pregnancy, even if subsequent cultures are negative, is not recommended 1, 2
• Confusing GBS bacteriuria management with that of other UTI pathogens is a common pitfall, as GBS requires specific attention due to neonatal risks 1
• Intrapartum prophylaxis is not needed if cesarean delivery is performed before onset of labor on a woman with intact amniotic membranes, regardless of GBS status 1, 3
• Treatment of asymptomatic GBS bacteriuria is different from other asymptomatic bacteriuria - all GBS bacteriuria should be treated regardless of symptoms or colony count 1, 2