In a case of neonatal meningitis, the etiologic bacteria was found to have propeies of 13-hemolysis, bacitracin resistance, CAMP positive. Which of the following is most likely causative agent?
## **Core Concept**
The question pertains to the identification of a bacterial pathogen causing neonatal meningitis, based on specific laboratory characteristics. The bacteria in question exhibits **β-hemolysis** (specifically, γ-hemolysis or a pattern described in relation to other hemolytic patterns), **bacitracin resistance**, and a **CAMP test positive** result. These properties are critical for differentiating among various streptococcal species.
## **Why the Correct Answer is Right**
The bacteria described is likely **Group B Streptococcus (GBS)**, also known as *Streptococcus agalactiae*. GBS is a leading cause of neonatal infections, including sepsis, pneumonia, and meningitis. The characteristics provided match GBS:
- **β-hemolysis**: GBS typically shows β-hemolysis on blood agar, which means it completely breaks down red blood cells, leaving a clear area around its colonies.
- **Bacitracin resistance**: Unlike Group A Streptococcus (GAS), which is sensitive to bacitracin, GBS is resistant.
- **CAMP test positive**: The CAMP (Christie–Atkins–Munch-Petersen) test is used to identify GBS. A positive result, indicated by enhanced hemolysis when Staphylococcus aureus is streaked near the GBS colonies, is characteristic.
## **Why Each Wrong Option is Incorrect**
- **Option A:** This option would be incorrect if it represents a bacterium not matching the given characteristics, such as GAS (*Streptococcus pyogenes*), which is bacitracin sensitive and CAMP test negative.
- **Option B:** If this option represents another type of streptococcus or pathogen not matching the described properties (e.g., *Streptococcus pneumoniae*, which is typically α-hemolytic), it would be incorrect.
- **Option C:** Similarly, if this option does not align with GBS characteristics, it would not be the correct answer.
## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that **Group B Streptococcus is a major cause of neonatal sepsis and meningitis**. Pregnant women are often screened for GBS colonization between 35-37 weeks of gestation, and those positive are offered intrapartum antibiotic prophylaxis to reduce the risk of neonatal infection.
## **Correct Answer:** D. Group B Streptococcus.