Sepsis in Newborns - Neonatal Sepsis


Indications for Testing

  • Fever in newborn; change in clinical status

Laboratory Testing

  • Initial testing – routine evaluation for sepsis, including CBC, blood culture, cerebrospinal fluid analysis from lumbar puncture, urinalysis
  • Good evidence supports use of C-reactive protein to rule out sepsis in full term infants
    • Recent studies suggest similar efficacy in preterm infants
    • Use in conjunction with white blood cell count and differential
    • Single measure may not be helpful
    • Obtain serial quantitative levels 24 hours after onset of symptoms of possible infection and obtain second measurement 24 hours later
    • Levels ≤10 mg/L indicate low probability of infection
  • Procalcitonin – proposed marker
    • May be used <24 hours after onset of critical illness as a marker of neonatal sepsis
    • Reliability too low to use as single marker in diagnosis of sepsis

Differential Diagnosis

Clinical Background

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


  • Incidence – 2/1,000 live births in the U.S.


  • C-reactive protein (CRP)
    • CRP is an acute phase reactant that binds to the following
      • 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 the following processes
      • 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 (eg, infection) if no other inflammatory event occurs
  • Procalcitonin
    • Acute phase reactant produced by monocytes and hepatocytes
    • Rises 4 hours after exposure to bacterial endotoxin
    • Peaks at 6-8 hours
    • Remains elevated at least 24 hours, then rapidly decreases

Clinical Presentation

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

Indications for Laboratory Testing

  • Tests generally appear in the order most useful for common clinical situations
  • Click on number for test-specific information in the ARUP Laboratory Test Directory
Test Name and Number Recommended Use Limitations Follow Up
CBC with Platelet Count and Automated Differential 0040003
Method: Automated Cell Count/Differential

Initial testing to help differentiate bacterial from viral etiology

Blood Culture 0060102
Method: Continuous Monitoring Blood Culture/Identification

Evaluate presence of infection in blood

Testing is limited to the University of Utah Health Sciences Center only

Electrolyte Panel 0020410
Method: Quantitative Ion-Selective Electrode/Enzymatic

Evaluate presence of electrolyte imbalance

Urinalysis, Complete 0020350
Method: Reflectance Spectrophotometry/Microscopy

Evaluate for evidence of urinary tract infection

Cerebrospinal Fluid (CSF) Culture and Gram Stain 0060106
Method: Stain/Culture/Identification

Testing  to rule out meningitis; identify organism causing meningitis

Cell Count, CSF 0095018
Method: Cell Count/Differential

Aid in differentiating bacterial from viral meningitis

Glucose, CSF 0020515
Method: Enzymatic

May be helpful in differentiating bacterial from viral etiology

Usually low (<10mg/dL) in bacterial meningitis and tuberculosis disease

Glucose, Plasma or Serum 0020024
Method: Quantitative Enzymatic

Quantifies glucose to match CSF glucose values

Protein, Total, CSF 0020514
Method: Reflectance Spectrophotometry

May be helpful in differentiating bacterial from viral etiology

C-Reactive Protein, Neonatal 0050181
Method: Immunoassay

Use as a marker of sepsis in newborns

Recent medical events resulting in tissue injury, infections, or inflammation may cause elevated CRP levels

Procalcitonin 0020763
Method: Immunofluorescence

Proposed at this time as an early marker (<24 hours) for sepsis in newborns

As various noninfectious conditions are known to induce procalcitonin as well, procalcitonin levels between 0.50 ng/mL and 2.00 ng/mL should be reviewed carefully to take into account the specific clinical background and condition(s) of the individual patient

Procalcitonin levels below 0.50 ng/mL do not exclude an infection because localized infections (without systemic signs) may also be associated with such low levels

Additional Tests Available
Click the plus sign to expand the table of additional tests.
Test Name and NumberComments
Urine Culture 0060131
Method: Culture/Identification