What antibiotic is appropriate for a urinary tract infection (UTI) caused by group B streptococcus (GBS)?

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Last updated: June 29, 2025View editorial policy

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From the Guidelines

Penicillin G or ampicillin is the recommended antibiotic treatment for urinary tract infections caused by group B streptococcus (GBS). According to the guidelines from the CDC 1, women with GBS isolated from the urine in any concentration during their current pregnancy should receive treatment according to current standards of care for urinary tract infection during pregnancy.

Key Considerations

  • For patients without penicillin allergy, penicillin G, 5 million units intravenously initial dose, then 2.5 million units intravenously every 4 hours until delivery, is recommended 1.
  • An alternative regimen is ampicillin, 2 g intravenously initial dose, then 1 g intravenously every 4 hours until delivery 1.
  • For patients with penicillin allergies, cefazolin, clindamycin, or erythromycin may be considered, depending on the severity of the allergy and susceptibility testing results 1.

Treatment Approach

  • It's essential to obtain urine cultures before starting treatment to confirm the diagnosis and check antibiotic susceptibility.
  • Patients should complete the full course of antibiotics even if symptoms improve quickly.
  • Increasing fluid intake can help flush bacteria from the urinary tract.
  • Follow-up cultures may be necessary to ensure complete eradication, especially in pregnant women or those with recurrent infections.

Special Considerations

  • Pregnant women with GBS urinary tract infection should be treated according to current standards of care for urinary tract infection during pregnancy.
  • Women with symptomatic or asymptomatic GBS urinary tract infection detected during pregnancy should be treated promptly to prevent complications.

From the FDA Drug Label

Vancomycin has been shown to be active against most strains of the following microorganisms, both in vitro and in clinical infections... Streptococcus agalactiae The antibiotic appropriate for a urinary tract infection (UTI) caused by group B streptococcus (GBS) is vancomycin 2.

From the Research

Antibiotic Treatment for Urinary Tract Infections with Group B Streptococcus

  • The choice of antibiotic for treating urinary tract infections (UTIs) caused by Group B Streptococcus (GBS) should be guided by antibiotic susceptibility testing, as resistance patterns can vary 3, 4, 5, 6.
  • According to studies, GBS isolates have shown sensitivity to certain antibiotics, including:
    • Penicillin 3, 5
    • Ampicillin, although resistance has been reported in some cases 3, 4, 5
    • Vancomycin, although some studies have found resistance 4, 5
    • Cephalothin, norfloxacin, and nitrofurantoin 5
  • However, GBS isolates have also shown resistance to certain antibiotics, including:
    • Clindamycin 3, 4, 6
    • Tetracycline 3, 4, 5
    • Erythromycin 6
  • It is essential to note that antibiotic resistance patterns can vary by region and over time, making it crucial to monitor local resistance patterns and adjust treatment regimens accordingly 7.
  • The diversity of GBS serotypes causing UTIs is also an important consideration, as different serotypes may have varying levels of antibiotic resistance 4, 6.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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