Sepsis in Newborns - Neonatal Sepsis

Dx
Background
Lab Tests

Diagnosis

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

Metabolic encephalopathy
Hypothyroidism

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.

Epidemiology

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

Pathophysiology

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
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