During a pediatric resuscitation workshop, you are asked: In children presenting with septic shock, which is the most common organism responsible for shock in the neonatal period (0–28 days)?

Explanation

## Most Common Organism Causing Septic Shock in Neonates **Key Point:** Group B Streptococcus (GBS) is the most common bacterial pathogen causing septic shock in neonates aged 0–28 days, followed closely by gram-negative organisms (especially E. coli with K1 capsule). ### Neonatal Sepsis Epidemiology | Organism | Frequency in Neonatal Sepsis | Age of Onset | Risk Factors | |---|---|---|---| | **Group B Streptococcus (GBS)** | 40–50% | 0–7 days (early-onset) | Maternal GBS colonization, prolonged rupture of membranes | | **E. coli (K1+)** | 30–40% | 0–7 days (early-onset) | Maternal urinary tract infection, vaginal colonization | | **Staphylococcus aureus** | 5–10% | 7–28 days (late-onset) | Nosocomial, IV lines, skin flora | | **Pseudomonas aeruginosa** | < 5% | Late-onset (> 7 days) | Nosocomial, ventilator-associated | ### Why GBS Is Most Common in Neonates **High-Yield:** GBS colonizes the maternal vaginal and rectal flora in 15–40% of pregnant women. Vertical transmission during delivery is the primary route of neonatal infection. Early-onset GBS disease (EOGBS) typically manifests within the first 24–72 hours of life with: - Fever or hypothermia - Respiratory distress (pneumonia) - Septic shock with poor perfusion - Meningitis (10–15% of cases) **Clinical Pearl:** The classic presentation of neonatal septic shock from GBS includes: - Maternal risk factors: GBS colonization, prolonged rupture of membranes (> 18 hours), maternal fever, prematurity - Rapid deterioration: tachypnea, grunting, retractions, cyanosis within hours - Shock signs: poor perfusion, weak cry, lethargy, seizures (if meningitis) ### Prevention and Management **Mnemonic:** **GBS Prevention in Pregnancy** — **G**roup B Strep screening at 35–37 weeks, **B**ased on risk factors or positive culture, **S**tart intrapartum antibiotics (penicillin G or ampicillin) at labor or rupture of membranes. 1. **Maternal screening:** Vaginal and rectal culture at 35–37 weeks of gestation 2. **Intrapartum antibiotic prophylaxis (IAP):** Penicillin G 5 million units IV loading dose, then 2.5 million units IV q4h until delivery 3. **Neonatal management:** If maternal GBS-positive or risk factors present, empiric ampicillin + gentamicin for 48 hours pending blood culture results **Warning:** Do NOT confuse early-onset (EOGBS, maternal transmission) with late-onset GBS disease (LOGBS, > 7 days, nosocomial or environmental source). EOGBS is far more common and more likely to present with shock. [cite:Park 26e Ch 9]