In a preterm neonate with meconium-stained amniotic fluid and a rash, which organism is most likely responsible for the infection?

In a preterm neonate with meconium-stained amniotic fluid and a rash, which organism is most likely responsible for the infection?

• A. Group B Streptococcus
• B. Escherichia coli
• C. Staphylococcus aureus
• D. Listeria

Answer: (D)

Transplacental infection with a food-borne, intracellular organism is a key clue here. Listeria monocytogenes can cross the placenta and infect the fetus, leading to severe neonatal sepsis and distinctive skin involvement known as granulomatosis infantiseptica, which presents with a disseminated pustular or vesiculopustular rash. When a preterm neonate is delivered into meconium-stained amniotic fluid, this can reflect fetal distress from intrauterine infection, including Listeria. The combination of preterm birth, meconium-stained fluid, and a widespread neonatal rash points toward Listeria as a likely cause. Other organisms listed are common culprits in early-onset neonatal sepsis (group B Streptococcus, Escherichia coli) and can cause sepsis or meningitis, but they don’t typically produce the characteristic disseminated rash seen with Listeria infections in neonates. Staphylococcus aureus tends to cause localized skin infections or bacteremia without the classic granulomatous skin presentation seen with Listeria in the neonate. So, the best fit is Listeria monocytogenes, given its pattern of transplacental transmission, association with fetal distress, and the distinctive neonatal rash.

Transplacental infection with a food-borne, intracellular organism is a key clue here. Listeria monocytogenes can cross the placenta and infect the fetus, leading to severe neonatal sepsis and distinctive skin involvement known as granulomatosis infantiseptica, which presents with a disseminated pustular or vesiculopustular rash. When a preterm neonate is delivered into meconium-stained amniotic fluid, this can reflect fetal distress from intrauterine infection, including Listeria. The combination of preterm birth, meconium-stained fluid, and a widespread neonatal rash points toward Listeria as a likely cause.

Other organisms listed are common culprits in early-onset neonatal sepsis (group B Streptococcus, Escherichia coli) and can cause sepsis or meningitis, but they don’t typically produce the characteristic disseminated rash seen with Listeria infections in neonates. Staphylococcus aureus tends to cause localized skin infections or bacteremia without the classic granulomatous skin presentation seen with Listeria in the neonate.

So, the best fit is Listeria monocytogenes, given its pattern of transplacental transmission, association with fetal distress, and the distinctive neonatal rash.