Antifungal Therapy in Neonates: When to Start

1. Prophylactic Antifungal Therapy

Who Gets Prophylaxis?

Drug of Choice: Fluconazole

• Dose: 3–6 mg/kg IV/oral
• Frequency: Twice weekly for 6 weeks (or duration of NICU stay with risk factors)
• Fluconazole prophylaxis reduces invasive candidiasis and all-cause mortality in ELBW infants

Alternative: Nystatin (oral/enteral)

• Effective in reducing invasive candidiasis in preterm infants
• Associated with reduced all-cause mortality in some studies
• Limitation: Cannot be used when there is ileus, GI disease, feeding intolerance, or hemodynamic instability — situations common in the lowest gestational age infants (< 750 g)

2. Empiric Antifungal Therapy

Risk Factors Warranting Empiric Antifungal:

• Birth weight < 1000 g or gestational age < 28 weeks
• Prolonged broad-spectrum antibiotic use (≥ 5–7 days)
• Central venous catheter (CVC) in situ
• Parenteral nutrition (TPN) use
• Endotracheal intubation / mechanical ventilation
• Abdominal surgery or bowel pathology (NEC, perforated bowel)
• Skin breakdown (e.g., skin excoriation)
• Prior fungal colonization (positive surveillance cultures from skin, rectum, oropharynx)
• Corticosteroid use (systemic)
• H2 blocker use
• Hyperglycemia unresponsive to insulin

Clinical Signs Prompting Empiric Therapy:

• Unexplained deterioration (apnea, bradycardia, temperature instability)
• Elevated CRP / thrombocytopenia (platelets < 100,000)
• Failure to respond to antibacterial therapy within 48–72 hours
• Thrombocytopenia is a particularly sensitive marker for neonatal candidiasis

Empiric Drug:

• Amphotericin B deoxycholate (1 mg/kg/day) — traditional choice
• Fluconazole — if not already on fluconazole prophylaxis and local resistance patterns allow
• Liposomal Amphotericin B (AmBisome) 3–5 mg/kg/day — preferred if CNS or renal involvement suspected

3. Targeted (Definitive) Antifungal Therapy

Indications:

• Positive blood culture for Candida species (most common: C. albicans, C. parapsilosis)
• Positive CSF culture — treat as neonatal Candida meningitis
• Positive urine culture (≥ 10,000 CFU/mL, especially via suprapubic aspirate)
• Positive culture from sterile site (peritoneal fluid, joint fluid)

Drug Selection by Syndrome:

Duration:

• Candidemia: at least 14 days from last positive blood culture + clinical improvement
• CNS candidiasis: minimum 3 weeks (often longer)

4. Summary Algorithm

Neonate in NICU
      │
      ├─ BW < 1000g or GA < 28 wks ──► PROPHYLAXIS (Fluconazole or Nystatin)
      │
      ├─ Clinical deterioration + multiple risk factors + no response to antibiotics
      │       ──► EMPIRIC antifungal (Amphotericin B or Fluconazole)
      │
      └─ Positive culture from sterile site
              ──► TARGETED antifungal (based on species + site)

Key Takeaways

• Prophylaxis is strongly recommended in ELBW infants (< 1000 g) with fluconazole twice weekly
• Empiric therapy should be initiated early in VLBW neonates with unexplained sepsis, thrombocytopenia, and ≥ 3 risk factors, especially if not responding to antibiotics
• Remove all central catheters as soon as candidemia is confirmed — this is a critical step
• A dilated fundoscopic exam, renal ultrasound, and echocardiogram should be performed in all neonates with confirmed candidemia to rule out disseminated disease
• Echinocandins are generally avoided as first-line in neonates with CNS involvement due to poor penetration