What antibiotic treats Group B Streptococcus (GBS) in pregnancy?

From the Guidelines

Penicillin is the recommended antibiotic for treating Group B Streptococcus (GBS) in pregnancy, specifically penicillin G, administered at a dose of 5 million units initially, followed by 2.5-3.0 million units every 4 hours, until delivery 1.

Alternative Options

• Ampicillin can be used as an alternative, at a dose of 2 grams intravenously every 4 hours, until delivery 1.
• For patients with a penicillin allergy,
  • Cefazolin is recommended for women at low risk of anaphylaxis, at a dose of 2 grams intravenously every 8 hours, until delivery 1.
  • Clindamycin or Vancomycin may be considered for women at high risk of anaphylaxis, but the risk of resistance should be assessed, with clindamycin administered at a dose of 900 mg intravenously every 8 hours, until delivery, and vancomycin at a dose of 1 gram intravenously every 12 hours, until delivery 1.

Key Considerations

• The duration of treatment is typically until delivery, and it is usually initiated at the onset of labor or when membranes are ruptured, to reduce the risk of GBS transmission to the newborn 1.
• Erythromycin is not recommended due to increasing resistance of GBS to macrolide antibiotics 1.
• It is essential to assess the risk of resistance when considering alternative antibiotics, especially for patients with a penicillin allergy 1.

From the FDA Drug Label

Clindamycin Injection, USP is indicated in the treatment of serious infections due to susceptible strains of streptococci, pneumococci, and staphylocci The antibiotic that treats Group B Streptococcus (GBS) in pregnancy is not explicitly stated in the label, but clindamycin is indicated for the treatment of serious infections due to susceptible strains of streptococci. However, the label does not specifically mention Group B Streptococcus or pregnancy.

• The use of clindamycin should be reserved for penicillin-allergic patients or other patients for whom a penicillin is inappropriate 2. Given the information provided, clindamycin may be considered for the treatment of GBS in pregnancy in penicillin-allergic patients, but the label does not provide direct evidence to support this use.

From the Research

Antibiotic Treatment for Group B Streptococcus (GBS) in Pregnancy

The following antibiotics are used to treat Group B Streptococcus (GBS) in pregnancy:

• Penicillin-G (or ampicillin) for GBS carriers without penicillin allergy 3
• Cefazolin for individuals with mild penicillin allergy 3, 4
• Clindamycin or erythromycin for mothers with severe penicillin allergy, when GBS' sensitivity is known 3, 4, 5
• Vancomycin for mothers with severe penicillin allergy, when GBS' sensitivity is unknown 3, 4, 6

Antibiotic Prophylaxis in GBS Positive Patients with Penicillin Allergy

Studies have shown that:

• Cefazolin and vancomycin are the most frequently prescribed antibiotics for intrapartum neonatal sepsis prophylaxis in GBS positive patients with penicillin allergy 4
• Antibiotic susceptibility testing is not always performed in GBS positive patients with penicillin allergy, which can lead to inadequate treatment 4
• The choice of antibiotic for GBS prophylaxis in patients with penicillin allergy can impact neonatal outcomes, such as increased frequency of postnatal blood draws 6

Efficacy of Antibiotics in Eradicating GBS Colonization

Research has found that:

• Intramuscular penicillin can reduce the rate of GBS colonization at delivery, but may not be sufficient as sole therapy 7
• The efficacy of antibiotics in eradicating GBS colonization can vary depending on the type of antibiotic and the individual patient's circumstances 7