Group B Streptococcus Treatment Guidelines

First-Line Treatment Options

The Centers for Disease Control and Prevention recommends penicillin G as the first-line treatment for Group B Streptococcus infections, with a dosing regimen of 5 million units IV initial dose, followed by 2.5-3.0 million units IV every 4 hours until delivery 2, 3
The Centers for Disease Control and Prevention suggests ampicillin as an acceptable alternative, with a dosing regimen of 2 g IV initial dose, then 1 g IV every 4 hours until delivery 1, 4

For patients not at high risk for anaphylaxis, the Centers for Disease Control and Prevention recommends cefazolin, with a dosing regimen of 2 g IV initial dose, then 1 g IV every 8 hours until delivery 1, 4
For patients at high risk for anaphylaxis, the Centers for Disease Control and Prevention recommends clindamycin, with a dosing regimen of 900 mg IV every 8 hours until delivery, if the GBS isolate is susceptible to clindamycin and erythromycin 2, 5
For patients at high risk for anaphylaxis, the Centers for Disease Control and Prevention recommends vancomycin, with a dosing regimen of 1 g IV every 12 hours until delivery, if susceptibility testing is not available or the isolate is resistant 2, 5

The Centers for Disease Control and Prevention notes that erythromycin is no longer recommended for GBS prophylaxis due to increasing resistance rates, up to 20.2% in studies 2
The Centers for Disease Control and Prevention reports that clindamycin resistance rates have increased to 3-15% in the US, necessitating susceptibility testing before use 6
The Centers for Disease Control and Prevention recommends testing for inducible clindamycin resistance for isolates that are susceptible to clindamycin but resistant to erythromycin 3

The Centers for Disease Control and Prevention prefers penicillin over ampicillin due to its narrower spectrum of activity, which may reduce selection for resistant organisms 6
The Centers for Disease Control and Prevention estimates the risk of anaphylaxis with penicillin administration at 4/10,000 to 4/100,000 recipients, which is far outweighed by the benefits of preventing GBS disease 6
The Centers for Disease Control and Prevention recommends intravenous administration as the only route for GBS treatment/prophylaxis due to higher concentrations achieved 6