Intrapartum antibiotic prophylaxis for GBS is given in which scenario?

• A. Penicillin G intrapartum if GBS-positive or unknown with risk factors; timing within labor is key
• B. Ampicillin intrapartum is given in all cases regardless of GBS status
• C. Erythromycin intrapartum is the preferred agent for GBS prophylaxis
• D. Clindamycin is used as first line for all cases

Answer: (A)

The key idea is that preventing early neonatal GBS infection relies on giving the right antibiotic during labor to mothers who are known to be colonized or who have risk factors with unknown status. Penicillin G is the first-line choice because it is highly effective and safe for this purpose. The timing matters because the antibiotic needs to reach adequate levels in the maternal and fetal circulation before the baby is delivered, typically requiring administration during labor with enough lead time (often several hours) to be protective.

Ampicillin isn’t used universally in all cases regardless of status, and erythromycin isn’t the preferred prophylactic agent due to resistance concerns. Clindamycin is reserved for penicillin-allergic patients when the GBS isolate is susceptible, not as the first-line option for all cases.