Which three organisms are commonly implicated in early-onset sepsis, what are risk factors, and what is the initial empiric antibiotic regimen for suspected sepsis in a term neonate?

• A. Organisms: Group B Streptococcus, Escherichia coli, Listeria monocytogenes; Risk factors: prolonged rupture of membranes, maternal fever/chorioamnionitis, prematurity; Initial empiric antibiotics: ampicillin plus gentamicin.
• B. Organisms: Staphylococcus aureus, Klebsiella; Risk factors: maternal diabetes; Initial empiric antibiotics: penicillin.
• C. Organisms: Group B Streptococcus, E. coli, Listeria monocytogenes; Initial empiric antibiotics: clindamycin.
• D. Organisms: Pseudomonas, Candida; Initial empiric antibiotics: vancomycin and cefepime.

Answer: (A)

Early-onset sepsis in a term newborn is most often due to Group B Streptococcus, Escherichia coli, and Listeria monocytogenes. Key risk factors include prolonged rupture of membranes, maternal fever or chorioamnionitis, and prematurity, all of which increase the infant’s exposure to these pathogens around birth. When sepsis is suspected, the initial empiric therapy for a term neonate is ampicillin plus gentamicin. Ampicillin covers Group B Streptococcus and Listeria, while gentamicin adds broad Gram-negative coverage, providing a targeted, effective first-line approach while awaiting culture results. Other regimens like penicillin alone miss Gram-negative organisms; clindamycin alone wouldn’t cover the common Gram-negatives; vancomycin with a broad-spectrum cephalosporin is used in different clinical scenarios (such as MRSA risk or specific NICU settings) but isn’t the standard first-line choice for a typical term neonate with suspected early-onset sepsis. Pseudomonas and Candida are more associated with late-onset sepsis or particular risk factors in the NICU.