Management of Group B Streptococcus Urinary Tract Infections

First‑Line Antimicrobial Therapy

Ampicillin 500 mg orally or intravenously every 8 hours for 7–14 days is recommended as a definitive first‑line regimen for GBS urinary tract infection. [@1]
Amoxicillin 500 mg orally every 8 hours for 7–14 days is an equivalent first‑line option. [@1]
Penicillin G administered intravenously (dose adjusted according to infection severity) is endorsed as the preferred β‑lactam for severe disease. [@2][@3]

Uncomplicated cystitis: 7 days of therapy. [@4][@8]
Complicated urinary tract infection: 7–14 days; extend to 14 days for men when prostatitis cannot be excluded. [@4]
Acute pyelonephritis: 7–14 days with a β‑lactam agent. [@8]
Shorter courses (5–7 days) may be appropriate when the patient has been afebrile for ≥48 hours and is hemodynamically stable. [@4]

Vancomycin 1 g intravenously every 12 hours is advised for patients at high risk of anaphylaxis (history of anaphylaxis, angioedema, respiratory distress, or urticaria with penicillin/cephalosporin). [@2][@3][@5]
Nitrofurantoin 100 mg orally every 6 hours is suitable for uncomplicated cystitis when a β‑lactam cannot be used. [@1]
Cefazolin – 2 g IV loading dose followed by 1 g IV every 8 hours – may be employed in patients with penicillin allergy who are not at high risk for anaphylaxis. [@5]

Intrapartum antibiotic prophylaxis for any pregnant woman with documented GBS bacteriuria: Penicillin G 5 million units IV loading dose, then 2.5–3.0 million units IV every 4 hours until delivery. [@2][@5]
Asymptomatic bacteriuria with <100,000 CFU/mL should not be treated with antibiotics outside of labor. [@6][@7]
GBS bacteriuria occurs in 2–4 % of pregnancies and signals heavy maternal colonization, warranting intrapartum prophylaxis to prevent neonatal early‑onset disease. [@6][@7]

All bullet points are derived from cited guideline or evidence sources; where multiple citations support the same recommendation, each is listed.

For patients with a high‑risk penicillin allergy (history of anaphylaxis, angioedema, respiratory distress, or urticaria), vancomycin 1 g IV every 12 hours is recommended for severe GBS urinary tract infection (CDC MMWR Recommendations, 2010) 1, 2.
Erythromycin should not be used as an alternative therapy for GBS urinary tract infection in high‑risk penicillin‑allergic patients because it is no longer considered an acceptable option (CDC MMWR Recommendations, 2010) 1.

All pregnant individuals with documented GBS bacteriuria (any colony count) should receive intrapartum antibiotic prophylaxis to prevent neonatal early‑onset disease (CDC MMWR Recommendations, 2010) 1, 2.
The recommended intrapartum regimen is penicillin G 5 million units IV loading dose, then 2.5–3.0 million units IV every 4 hours until delivery (CDC MMWR Recommendations, 2010) 1, 2.