Maternal-Fetal Antimicrobials

Indicators and dose

Mechanism of Action and Specific Obstetric Indications

Penicillin G Sodium (Wall Bactericide)

Betal-lactam inhibitor of bacterial peptidoglycan cross-linking:

• Intrapartum prophylaxis of Group B Streptococcus (GBS / S. agalactiae): A mandatory choice to prevent early neonatal sepsis, meningitis and pneumonia in the newborn.
• Treatment of gestational syphilis (Penicillin G benzathine).
• Treatment of gestational listeriosis (associated with ampicillin).

Clindamycin + Gentamicin (Combined Scheme)

Synergistic ribosomal blockade (50S anaerobic / 30S Gram-negative):

• Empirical treatment of active chorioamnionitis (intra-amniotic infection) after prolonged rupture of membranes.
• Treatment of acute postpartum endometritis.
• Intrapartum prophylactic alternative scheme for GBS in patients with confirmed severe allergy (anaphylaxis) to penicillin.

Dosage and Protocols

• Intrapartum GBS prophylaxis (Penicillin G): Initial bolus of 5 million IU IV slowly, followed by doses of 2.5 to 3 million IU IV every 4 hours until delivery is complete. A minimum of 4 hours of infusion should be guaranteed prior to birth to achieve optimal cord-fetal bactericidal levels.
• Chorioamnionitis / Endometritis (Clindamycin + Gentamicin): Clindamycin 900 mg IV every 8 hours + Gentamicin 1.5 mg/kg IV every 8 hours (or single daily dose of 5 mg/kg), maintaining the combination until the patient is afebrile for more than 24-48 hours.

Pregnancy and Breastfeeding

FDA risk categories should always be considered when selecting the antimicrobial therapy of choice. Generally compatible with breastfeeding, with care to monitor alterations in the infant's intestinal flora (such as transient diarrhea or oral candidiasis).

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Gestational Safety and Teratogenicity Profiles