Neonatal Sepsis

Early-Onset Sepsis (EOS) - Evaluated < 72 Hours

• Pathogens: Group B Streptococcus (GBS) [most common term], E. coli [most common preterm/VLBW], Listeria monocytogenes, Haemophilus influenzae.
• Risk factors explicitly evaluated via Kaiser Sepsis Calculator (for >= 34 weeks): Maternal temp >= 38.0°C (100.4°F), ROM >= 18 hours, maternal GBS status (+ in adequate IAP), gestational age.
• Clinical signs: Temp instability (fever >38°C or hypothermia <36°C), tachypnea (>60/min), grunting, apnea, poor perfusion / capillary refill > 3s, lethargy.

Late-Onset Sepsis (LOS) - Evaluated > 72 Hours

• Pathogens: Coagulase-negative staphylococci (CONS) [most common overall in NICU], S. aureus (MRSA/MSSA), Gram-negative rods (Klebsiella, Pseudomonas, E. coli), Candida species.
• Risk factors: Indwelling central venous catheters (UVC, PICC), prolonged mechanical ventilation, extensive mucosal injury (NEC), prolonged TPN.

Rigorous Diagnostic Workup

• Blood Culture: Obtain BEFORE antibiotics. Minimum 1 mL exact volume ensures 99% pediatric bacteremia detection (low volumes drastically increase false negatives).
• CBC with differential: Absolute Neutrophil Count (ANC) < 1,000/mm³ is highly specific. I/T ratio (Immature to Total neutrophil ratio) > 0.2 is suggestive of infection.
• CRP or Procalcitonin: Serial CRPs at 0-24h and 48h (requires 10-12 hours to peak). 2 normal CRPs > 24 hours apart have ~99% negative predictive value to rule out bacterial sepsis.
• Lumbar Puncture (CSF): Must evaluate if blood culture is positive, clinical signs of meningitis exist (seizures/bulging fontanelle), or if infant is critically failing EOS empiric therapy.
• Urine Culture (Catheterized/Suprapubic ONLY): Not indicated in < 72 hr (EOS), highly indicated in > 72 hr (LOS).

Accurate Empiric Antibiotic Therapy

• EOS Empiric Therapy: Ampicillin (covers GBS, Listeria) PLUS an Aminoglycoside (Gentamicin, covers Gram-negatives) OR Cefotaxime (avoid Ceftriaxone in neonates due to biliary sludging/hyperbilirubinemia).
• LOS Empiric Therapy: Vancomycin (covers CONS and MRSA) PLUS Gentamicin OR a third/fourth-gen cephalosporin (Cefotaxime/Cefepime, depending on unit antibiogram for Pseudomonas).
• Gentamicin monitoring: Strict peak (5-12 mcg/mL) and trough (<1.0 mcg/mL) check prior to 3rd dose to prevent irreversible ototoxicity and nephrotoxicity.
• Duration: 48 hours for rule-out (discontinue if cultures are negative and baby is stable). 7-10 days for proven bacteremia; 14-21 days for meningitis or complicated infections (e.g., osteomyelitis).

Diagnostic & Management Algorithm

• Early Onset Sepsis Matrix Algorithm: [START] Chorioamnionitis OR ROM > 18h -> [CALCULATION] Kaiser EOS Risk Calculator -> [DECISION] High Risk / Clinical Illness? -> [YES] Blood Culture + Ampicillin/Gentamicin -> [NO] Vitals Q4H Observation

References

1. Puopolo KM, Benitz WE, Zaoutis TE; AAP Committee on Fetus and Newborn. Management of Neonates Born at >= 35 0/7 Weeks' Gestation With Suspected or Proven Early-Onset Bacterial Sepsis. Pediatrics.
2. Wortham JM, Hansen NI, Schrag SJ, et al. Chorioamnionitis and Culture-Confirmed, Early-Onset Neonatal Infections. Pediatrics.