Treatment of Group B Streptococcus in Urine
The treatment for Group B streptococcus (GBS) in urine depends on colony count and pregnancy status, with penicillin G being the first-line therapy for most GBS infections. 1
Asymptomatic GBS Bacteriuria
During Pregnancy
- Women with GBS bacteriuria during pregnancy (regardless of colony count) should receive intrapartum antibiotic prophylaxis (IAP) at the time of labor or rupture of membranes to prevent early-onset neonatal GBS disease. 1, 2
- For significant bacteriuria (≥100,000 CFU/mL), treatment at the time of detection is recommended 2
- For low colony counts (<100,000 CFU/mL), immediate antibiotic treatment is not recommended for prevention of adverse outcomes such as pyelonephritis, chorioamnionitis, or preterm birth 2
- Women with documented GBS bacteriuria should not be re-screened in the third trimester as they are presumed to be GBS colonized 2
Non-Pregnant Adults
- Asymptomatic GBS colonization generally does not require treatment 1
- Routine antibiotic treatment of asymptomatic carriers is not recommended except in specific situations (e.g., pregnancy) 1
Symptomatic GBS Urinary Tract Infection
First-Line Treatment
- Penicillin G is the first-line therapy for most GBS infections 1
- Recommended dose: 5 million units IV initial dose, followed by 2.5-3.0 million units IV every 4 hours until delivery (in pregnancy) 1
- For non-pregnant patients with UTI symptoms, treatment should be based on susceptibility testing
Alternative Antibiotics (for penicillin allergy)
- Ampicillin: 2 g IV initial dose, then 1 g IV every 4 hours 1
- Cefazolin: 2 g IV initial dose, then 1 g IV every 8 hours 1
- For true penicillin allergy: Erythromycin or clindamycin (if susceptible) 3
- For UTI specifically: Nitrofurantoin is effective against GBS and has been recommended for GBS bacteriuria 4
Special Considerations
Antibiotic Resistance
- While all GBS isolates remain sensitive to penicillin, some studies have shown intermediate or decreased sensitivity in 15% of isolates 4
- Resistance rates for other antibiotics:
- Azithromycin and ceftriaxone: 31%
- Clindamycin: 19%
- Cefazolin: 15%
- Cefamandole: 13% 4
Pregnancy-Specific Management
- Women with GBS in urine during pregnancy should receive IAP at delivery, independent of the colony count 5
- The optimal IAP should be administered for at least 4 hours before delivery, though even 2 hours of antibiotic exposure reduces GBS vaginal colony counts 1
- Penicillin allergy testing has been shown to be safe in pregnancy 5
Management of GBS Bacteremia (if UTI leads to bloodstream infection)
- Evaluate for signs of sepsis and assess for potential sources of infection 1
- Consider risk factors for severe infection (immunocompromise, diabetes, liver disease) 1
- Remove infected catheters if present 1
- Obtain follow-up blood cultures to document clearance of bacteremia 1
Important Caveats
- For pregnant women with GBS bacteriuria, antibiotic sensitivities should be determined, especially if penicillin allergy is present 4
- The greatest risk associated with penicillin therapy is anaphylactic reaction, with an estimated frequency of about 5 cases per 10,000 treatments 3
- The dosing interval for penicillin G should be 4 hours to ensure anti-GBS activity in all patients; more frequent dosing does not increase activity 6