Early-onset sepsis

EOS - The First 72 Hours

• Onset: Birth to <72 hours.
• Workup:
  • Screening: CBC (I/T ratio >0.2), CRP (>10 mg/L).
  • Definitive: Blood Culture.
• Empirical Antibiotics:
  • Ampicillin + Gentamicin.

⭐ In India, the most common organisms causing EOS are E. coli and Klebsiella pneumoniae, unlike the West where Group B Streptococcus dominates.

The Usual Suspects - Bugs & Risks

• Common Pathogens: 📌 GEL
  • Group B Streptococcus (GBS): Most common overall.
  • E. coli: Most common in preterms.
  • Listeria monocytogenes & Klebsiella.
• Maternal Risk Factors:
  • Prolonged Rupture of Membranes (PROM) > 18 hrs.
  • Preterm delivery < 37 weeks.
  • Intra-amniotic infection (chorioamnionitis).
  • Maternal GBS colonization.
  • Intrapartum fever > 38°C.

⭐ E. coli is the leading cause of early-onset sepsis and meningitis in preterm neonates.

Spotting Sepsis - Subtle Signs

• Systemic: Temperature instability (hypothermia <36.5°C or fever >38°C), lethargy, poor cry, hypotonia.
• Cardio-Respiratory:
  • Tachypnea (>60/min), grunting, retractions, apnea.
  • Tachycardia (>160/min) or bradycardia (<100/min).
  • Poor perfusion: ↑Capillary refill time >3s, mottling, cool peripheries.
• GI/CNS: Refusal to feed, vomiting, abdominal distension, jaundice, seizures, bulging fontanelle.

⭐ The triad of respiratory distress, temperature instability, and feeding difficulty is highly suggestive of neonatal sepsis.

The Sepsis Workup - Lab Lockdown

• Gold Standard: Blood culture is definitive. Collect >1 mL before starting antibiotics.

• Sepsis Screen (Töllner's Score): A combination of tests to guide empirical therapy.

  • Hematology:
    • TLC: <5000/mm³ (leukopenia) is a strong predictor.
    • Absolute Neutrophil Count (ANC): See reference charts for age.
    • Immature/Total (I/T) Neutrophil Ratio: >0.2 is highly suggestive.
  • Acute Phase Reactants:
    • C-Reactive Protein (CRP): >10 mg/L. Serial measurements (24-48h) are more valuable. ↑ levels indicate infection.
    • Micro-ESR: >15 mm in the first hour.

• Lumbar Puncture (CSF analysis): Mandatory for all neonates with suspected sepsis.

• Chest X-ray: Indicated if respiratory signs are present.

⭐ A negative sepsis screen (especially CRP and I/T ratio) at 24-48 hours has a high negative predictive value, allowing for safe discontinuation of antibiotics if blood culture is also negative.

Antibiotic Arsenal - Treatment Tactics

• Empiric Therapy: Initiate immediately after cultures.
  • First Line: Ampicillin + Gentamicin
  • Covers GBS, E. coli, Listeria.
• Suspected Meningitis: Ampicillin + Cefotaxime
  • Gentamicin has poor CSF penetration.

⭐ Exam Favourite: Cefotaxime is preferred over Ceftriaxone in neonates. Ceftriaxone displaces bilirubin from albumin, increasing the risk of kernicterus, and can cause biliary sludging.

Duration of Therapy

• Bloodstream infection: 10-14 days
• Meningitis: 14-21 days

High-Yield Points - ⚡ Biggest Takeaways

• The most common cause of early-onset sepsis is Group B Streptococcus (GBS), acquired vertically.
• Onset occurs within the first 72 hours of life, distinguishing it from late-onset sepsis.
• Key risk factors: maternal GBS colonization, preterm delivery, and prolonged rupture of membranes (>18h).
• Respiratory distress is the most frequent clinical sign; presentation is often subtle.
• Blood culture remains the gold standard for diagnosis.
• First-line empiric therapy is IV Ampicillin and Gentamicin.