What are the laboratory results for a diagnosis of neonatal sepsis?

From the Guidelines

Neonatal sepsis laboratory evaluation should include a complete blood count with differential, blood culture, C-reactive protein (CRP), and procalcitonin, with empiric antibiotic treatment initiated promptly, typically with ampicillin plus gentamicin or a third-generation cephalosporin, as recommended by the most recent guidelines 1.

Laboratory Evaluation

The laboratory evaluation for neonatal sepsis typically includes:

• A complete blood count with differential to assess for leukocytosis (>30,000/μL) or leukopenia (<5,000/μL), both of which are concerning for infection
• Blood culture, which is the gold standard for diagnosis but takes 24-48 hours for results
• C-reactive protein (CRP) levels, which typically rise 6-8 hours after infection onset and peak at 24-48 hours, with values >10 mg/L being concerning
• Procalcitonin levels, which rise within 2-4 hours of infection and values >2 ng/mL strongly suggest bacterial sepsis

Empiric Antibiotic Treatment

Empiric antibiotic treatment should be initiated promptly, with the most recent guidelines recommending:

• Ampicillin plus gentamicin as first-line treatment 1
• A third-generation cephalosporin as an alternative option
• The use of cefotaxime or ceftriaxone as second-line treatment in certain cases 1

Additional Tests

Additional tests may include:

• Cerebrospinal fluid analysis if meningitis is suspected
• Urinalysis and urine culture
• Chest X-ray if respiratory symptoms are present These tests should be obtained promptly before starting empiric antibiotics, and the results should be used to narrow down the antibiotic treatment once available. Early detection through these laboratory markers is crucial as neonates often present with subtle, nonspecific symptoms rather than obvious signs of infection. The WHO recommendations for empiric treatment of neonatal sepsis, as outlined in the systematic review 1, should be considered in conjunction with the most recent guidelines 1.

From the Research

Neonatal Sepsis Lab Results

• The diagnosis of neonatal sepsis is often suspected, but proven sepsis is found in less than 10% to 25-30% of cases 2.
• Laboratory tests have low value in suspected neonatal sepsis, and clinical evaluation is crucial 2.
• Blood cultures, urine cultures, and other cultures are important for diagnosis, but their interpretation requires careful consideration 2.
• The use of antibiotics in neonatal sepsis is a concern, with potential overuse and resistance, as well as under-recognition and delayed treatment 3.
• Various sepsis risk assessment tools and biomarkers are being developed to aid in the diagnosis of neonatal sepsis 3.

Diagnostic Challenges

• There is no clear consensus definition for sepsis in neonates, making diagnosis difficult 3.
• A positive blood culture is considered the gold standard for definitive diagnosis, but "culture negative" or "suspected" sepsis is common 3.
• The accurate and timely diagnosis of sepsis in neonates presents significant difficulties, with varying rates of "culture negative" or "suspected" sepsis worldwide 3.

Treatment and Antibiotic Use

• The use of ampicillin and gentamicin is recommended for early-onset neonatal sepsis, but resistance to ampicillin is common, particularly in E coli 4.
• The concurrent use of cefotaxime with ampicillin may be associated with an increased risk of death compared to the use of gentamicin with ampicillin 5.
• Alternative antibiotic regimens are being developed to address the growing problem of antibiotic resistance, including the use of amikacin, tobramycin, fosfomycin, flomoxef, and cefepime 6.