A neonate develops signs of meningitis at seven days of birth. The presence of which of the following infectious agent in the maternal genital tract can be the causative agent of this disease –
**Core Concept**
Group B streptococcus (GBS) is a gram-positive bacterium that is a common inhabitant of the human gastrointestinal and genitourinary tracts. It is a leading cause of neonatal sepsis and meningitis, particularly in the first week of life.
**Why the Correct Answer is Right**
GBS can colonize the maternal genital tract and be transmitted to the neonate during delivery, leading to invasive disease. The bacteria can cross the placenta or be acquired during passage through the birth canal, resulting in early-onset sepsis and meningitis. The pathogenesis involves the production of beta-hemolysin and other virulence factors that contribute to the bacteria's ability to invade and cause disease in neonates.
**Why Each Wrong Option is Incorrect**
* **Option A:** Escherichia coli (E. coli) is another common cause of neonatal sepsis, but it is not typically associated with maternal genital tract colonization.
* **Option B:** Listeria monocytogenes is a rare cause of neonatal meningitis and is not typically transmitted from the maternal genital tract.
* **Option D:** Staphylococcus aureus can cause neonatal sepsis, but it is not typically associated with maternal genital tract colonization.
**Clinical Pearl / High-Yield Fact**
GBS colonization in pregnant women is a significant risk factor for neonatal sepsis and meningitis. Screening for GBS colonization is recommended in pregnant women at 35-37 weeks of gestation, and intrapartum antibiotics may be administered to prevent early-onset disease.
**Correct Answer: C. Group B streptococcus (GBS)**