A 7 day old infant develops symptoms of neonatal septicemia. Most likely cause is –
## **Core Concept**
Neonatal septicemia, also known as neonatal sepsis, is a serious infection that occurs in newborns, typically within the first 28 days of life. It is a leading cause of morbidity and mortality in this vulnerable population. The most common causes of neonatal septicemia vary depending on the age of the infant, with early-onset sepsis (within the first 72 hours of life) often related to maternal genital tract colonization.
## **Why the Correct Answer is Right**
The correct answer, **Group B Streptococcus (GBS)**, is a leading cause of neonatal sepsis, particularly in the early-onset form (within the first 72 hours of life). GBS is a common inhabitant of the maternal genital and gastrointestinal tracts. During delivery, the newborn can be exposed to GBS, leading to infection. GBS is known for its virulence in newborns, causing severe disease, including sepsis, pneumonia, and meningitis.
## **Why Each Wrong Option is Incorrect**
- **Option A:** Although *Escherichia coli* is indeed a cause of neonatal sepsis, particularly in late-onset sepsis (after 72 hours of life), it is not the most likely cause overall when considering both early and late-onset disease.
- **Option B:** *Staphylococcus aureus* can cause neonatal sepsis but is more commonly associated with late-onset infections or with specific exposures such as central lines or surgical sites.
- **Option C:** *Listeria monocytogenes* can cause neonatal sepsis, especially in outbreaks or with specific exposures like eating contaminated food, but it is less common than GBS.
## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the risk factors for early-onset GBS sepsis include maternal colonization with GBS, preterm labor, prolonged rupture of membranes, and intrapartum fever. The American College of Obstetricians and Gynecologists (ACOG) recommends screening for GBS colonization in all pregnant women at 36-37 weeks of gestation and offers intrapartum antibiotic prophylaxis to those who are positive.
## **Correct Answer:** . **Group B Streptococcus**