A term neonate develops respiratory distress and temperature instability at 36 hours of life. The mother had fever during labor and the amniotic fluid was foul smelling. Blood culture grows faintly hemolytic colonies of short gram-positive rods that show tumbling motility. Which organism is responsible and what is the appropriate addition to therapy?

• A Listeria monocytogenes; add gentamicin to ampicillin ✓
• B Group B Streptococcus; add clindamycin
• C Enterococcus faecalis; add vancomycin
• D Escherichia coli; add cefotaxime

Explanation

Tumbling motility on wet mount and short gram-positive rods identify Listeria monocytogenes, acquired transplacentally or from contaminated food such as unpasteurized dairy. It classically causes early-onset sepsis associated with maternal fever and meconium-stained or foul amniotic fluid. Listeria is inherently resistant to cephalosporins, so cefotaxime alone would fail. Treatment is intravenous ampicillin combined with gentamicin for synergy, later de-escalating to ampicillin alone once cultures clear.

Reference: Nelson Textbook of Pediatrics, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.