Streptococcus causing neonatal meningitis among the following is:
**Core Concept**
Group B Streptococcus (GBS) is a gram-positive bacterium that is a leading cause of neonatal sepsis and meningitis, particularly in the first week of life. GBS colonization in the maternal genital tract is the primary source of infection, which can be transmitted to the newborn during delivery.
**Why the Correct Answer is Right**
GBS produces several virulence factors, including the capsule, which is essential for its ability to cause invasive disease. The capsule is composed of polysaccharides and is encoded by the _bca_ gene. GBS also produces C-carbohydrate and other surface proteins that contribute to its ability to adhere to and invade host cells. In neonates, GBS meningitis often presents with severe symptoms, including seizures, apnea, and respiratory distress.
**Why Each Wrong Option is Incorrect**
* **Option A:** While Streptococcus pneumoniae is a common cause of meningitis in adults, it is not the primary cause of neonatal meningitis.
* **Option B:** Streptococcus agalactiae (Group B Streptococcus) is the correct answer, but the question asks for the option that is not correct, so this section is not applicable. However, I will still label the other options for clarity.
* **Option C:** Haemophilus influenzae type b (Hib) is a leading cause of meningitis in children over 6 months of age, but it is not typically associated with neonatal meningitis.
* **Option D:** E. coli is a common cause of urinary tract infections and bacteremia in neonates, but it is not typically associated with meningitis.
**Clinical Pearl / High-Yield Fact**
GBS colonization in pregnant women is a significant risk factor for neonatal GBS disease. Screening for GBS colonization is recommended for all pregnant women at 35-37 weeks of gestation, and intrapartum antibiotic prophylaxis (IAP) is recommended for women who test positive.
**Correct Answer: C. Streptococcus agalactiae**