Cefazolin Dosing for GBS Prophylaxis

Dosing Regimen

The Centers for Disease Control and Prevention recommends an initial loading dose of 2 g IV, followed by 1 g IV every 8 hours until delivery for GBS prophylaxis in penicillin-allergic pregnant women without high-risk allergy features 1, 2
The maintenance dose of 1 g IV every 8 hours until delivery is recommended for GBS prophylaxis in penicillin-allergic pregnant women without high-risk allergy features 1, 2

Cefazolin is the preferred alternative for penicillin-allergic pregnant women who do NOT have a history of anaphylaxis, angioedema, respiratory distress, or urticaria following penicillin or cephalosporin administration, as recommended by the Centers for Disease Control and Prevention 1, 2
The Centers for Disease Control and Prevention recommends cefazolin based on pharmacologic data showing it achieves effective intraamniotic concentrations 1, 2

The Centers for Disease Control and Prevention advises against using cefazolin in patients with high-risk penicillin allergy features, including history of anaphylaxis, angioedema, respiratory distress, or urticaria following penicillin or cephalosporin administration 1, 2
Approximately 10% of penicillin-allergic patients also have immediate hypersensitivity to cephalosporins, according to the Centers for Disease Control and Prevention 3

For patients at high risk for anaphylaxis, the Centers for Disease Control and Prevention recommends Clindamycin 900 mg IV every 8 hours (if GBS isolate is susceptible to both clindamycin and erythromycin) 4
The Centers for Disease Control and Prevention also recommends Vancomycin 1 g IV every 12 hours (if susceptibility testing unavailable or isolate is resistant) for patients at high risk for anaphylaxis 4

The Centers for Disease Control and Prevention advises against using cefazolin in patients with documented high-risk penicillin allergy, as approximately 10% will cross-react 3
The Centers for Disease Control and Prevention recommends not underdosing, as the 2 g loading dose is essential to achieve rapid therapeutic levels 1, 2
The Centers for Disease Control and Prevention also recommends not extending the dosing interval beyond 8 hours, as this is longer than typical cefazolin dosing due to pregnancy-related pharmacokinetic changes 1, 2
Verifying allergy history is crucial, as many reported penicillin allergies are not true IgE-mediated reactions, and patients may be candidates for penicillin rather than cefazolin, according to the Centers for Disease Control and Prevention 3