Systemic infections are responsible for a significant number of hospitalizations during the neonatal period.  Nonspecific symptoms make the differentiation between bacterial and viral illnesses difficult and make the use of markers such as C-reactive protein useful as an aid in differentiation.

Epidemiology

• Incidence - WHO (2000) estimates that 42% of neonatal mortality is caused by infections

Pathophysiology

• C-reactive protein (CRP) is an acute phase reactant that binds to:
  • Polysaccharides present in many bacteria, fungi and protozoal parasites
  • Phosphocholine
  • Phosphatidylcholines such as lecithins
  • Polyanions such as nucleic acids
• Once complexed, CRP becomes an activator of the classical complement pathway by:
  • Recognizing potentially toxic autogenous substances released from damaged tissues
  • Binding these toxic substances
  • Detoxifying or clearing the toxic substances from the blood
• CRP peaks and begins to decrease within 48 hours of acute insult if no other inflammatory event occur

Clinical Presentation

• Nonspecific signs and symptoms
  • Fever
  • Lethargy
  • Irritability
  • Apnea
  • Abdominal distention
• Rapid progression of sepsis with accompanying shock without early treatment

Diagnosis

• Indications for Testing - fever in newborn,,change in clinical status
• Laboratory testing
  • Basic lab tests - CBC, blood culture, CSF fluid analysis from lumbar puncture
  • Good evidence supports use of CRP to rule out sepsis in full-term infants
    • Recent studies suggest similar efficacy in pre-term infants
    • Use in conjunction with white blood cell count and differential
    • Obtain serial quantitative levels 24 hours after onset of symptoms of possible infection and obtain second measurement 24 hours later
    • Levels less than or equasl to10 mg/L indicate low probability of infection
  • Procalcitonin - proposed marker
    • May be used <24 hours as a marker of neonatal sepsis

Differential Diagnosis

• Metabolic encephalopathy
• Hypothyroidism