What is the treatment for Streptococcus agalactiae (Group B Streptococcus, GBS) in urine?

Treatment of Streptococcus agalactiae (Group B Streptococcus) in Urine

For Group B Streptococcus (GBS) in urine, treatment should be provided for pregnant women at any concentration, while in non-pregnant adults, treatment is only indicated for symptomatic infections or colony counts ≥100,000 CFU/mL. 1

Treatment Approach Based on Patient Population

Pregnant Women

• All GBS bacteriuria during pregnancy requires treatment regardless of colony count or symptoms 1
• First-line treatment options:
  • Amoxicillin-clavulanic acid
  • Nitrofurantoin
  • Sulfamethoxazole-trimethoprim 1
• Important: Pregnant women with GBS bacteriuria at any point during pregnancy will also require intrapartum antibiotic prophylaxis (IAP) during labor 1

Non-Pregnant Adults

• Treatment indicated only if:
  • Patient is symptomatic OR
  • Colony count ≥100,000 CFU/mL 1
• Colony counts of 10,000-49,000 CFU/mL without symptoms should not be treated 1
• More aggressive treatment approach should be considered in high-risk groups:
  • Patients with urinary tract abnormalities
  • Patients with chronic renal failure 1

Antibiotic Selection

First-Line Options

• Amoxicillin-clavulanic acid
• Nitrofurantoin
• Sulfamethoxazole-trimethoprim 1
• Penicillin G (all isolates remain fully susceptible) 2, 3, 4

Alternative Options (for penicillin-allergic patients)

• Check susceptibility testing before using alternatives due to increasing resistance patterns:
  • Erythromycin (resistance up to 18.3%)
  • Clindamycin (resistance up to 26.6%) 1, 3, 4

Special Considerations for UTI Treatment

• Nitrofurantoin is specifically recommended for GBS bacteriuria treatment 4
• Fluoroquinolones (ciprofloxacin, ofloxacin) should be reserved for pyelonephritis or severe cases 1, 4
• Broad-spectrum antibiotics like carbapenems should be avoided unless multidrug resistance is confirmed 1

Intrapartum Antibiotic Prophylaxis for Pregnant Women

For pregnant women who had GBS bacteriuria at any point during pregnancy, IAP is required during labor with the following regimens:

First-Line IAP Regimen

• Penicillin G: 5 million units IV initial dose, then 2.5-3.0 million units IV every 4 hours until delivery 1, 5
  • Note: Research supports that the dosing interval should be 4 hours to ensure anti-GBS activity 5

Alternative IAP Regimens

• Ampicillin: 2 g IV initial dose, then 1 g IV every 4 hours until delivery 1
• Cefazolin: 2 g IV initial dose, then 1 g IV every 8 hours until delivery (for penicillin-allergic patients without anaphylaxis) 1
• Clindamycin: Only if GBS isolate is tested and susceptible (for patients with severe penicillin allergy) 1

Important Clinical Pearls

• Treating GBS colonization with oral antibiotics in the third trimester does not eliminate GBS from the genitourinary tract; recolonization after treatment is common 1
• IAP is most effective when administered at least 4 hours before delivery 1
• Local antibiotic resistance patterns should be considered when selecting antibiotics 1, 2, 3
• The macrolide-lincosamide-streptogramin B (MLSB) phenomenon has been noted in some GBS isolates, which can affect treatment efficacy 2
• Pregnant women should be screened for GBS colonization at 36 0/7 to 37 6/7 weeks of gestation with vaginal-rectal cultures 1
• Increasing resistance to macrolides and clindamycin has been reported, highlighting the importance of susceptibility testing 3, 4

Common Pitfalls to Avoid

• Do not treat asymptomatic bacteriuria with colony counts <100,000 CFU/mL in non-pregnant adults 1
• Do not use antibiotics before the intrapartum period to eradicate GBS genitorectal colonization in pregnant women 1
• Do not assume all GBS isolates are susceptible to macrolides or clindamycin without susceptibility testing 1, 2, 3, 4
• Do not discontinue breastfeeding for mothers with GBS infection who are receiving appropriate antibiotic treatment 1