First-lineGeneric
Ampicillin
Aminopenicillin (β-lactam)
IV penicillin for GBS prophylaxis and Listeria-suspected chorioamnionitis.
IVIM
First-line for
- GBS intrapartum prophylaxis (alternative to benzylpenicillin)
- Chorioamnionitis (with gentamicin ± metronidazole)
- Listeria monocytogenes in pregnancy
- Postpartum endometritis
Mechanism
PBP-binding β-lactam; broader Gram-neg cover than penicillin G, retains Listeria activity.
“Amp + Gent + Metro = triple for chorio”
- Loading 2 g IV then 1 g q4h intrapartum
- Add metro after delivery if not already in regimen
Dosing
- GBS prophylaxis
- 2 g IV load, then 1 g IV q4h until delivery
- Chorioamnionitis
- 2 g IV q6h
Contraindications
- AbsolutePenicillin allergy
- CautionRenal impairment — dose adjust
Side effects
- Rash (esp. EBV co-infection)
- GI upset
- Phlebitis at IV site
- ↑ LFTs
Fetal & maternal notes
- • Safe across pregnancy
- • Listeria coverage is its major advantage over cephalosporins
Key interactions
Allopurinol
Caution↑ rash
Methotrexate
Avoid↑ toxicity
Clinical pearls
- 💡 First-line IV agent for GBS in non-penicillin-allergic women alongside benzylpenicillin
- 💡 Switch to vancomycin if anaphylactic allergy
Content last reviewed: REPLACE_ME (e.g. 2026-07)
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