What is the management plan for a newborn with fever, tachycardia, and rhinovirus infection, along with increasing liver function tests (LFTs) and a planned lumbar puncture (LP) and echocardiogram (echo)?

Management of Newborn with Fever, Tachycardia, Rhinovirus, and Elevated LFTs

Proceed with the Planned Lumbar Puncture and Echocardiogram

Your plan to perform the lumbar puncture with IR guidance and obtain an echocardiogram is appropriate and should be completed today. Despite the rhinovirus-positive culture, bacterial co-infection—particularly meningitis—remains a critical diagnostic consideration that cannot be excluded without CSF analysis, and the combination of fever, tachycardia, and elevated LFTs raises concern for myocarditis. 1, 2

Key History and Physical Examination Findings to Assess

Neurological Assessment

• Level of consciousness: Document Glasgow Coma Score; a GCS <13 is a contraindication to LP 3, 1
• Seizure activity: New-onset seizures require imaging before LP 3
• Focal neurological signs: Check for asymmetric movements, abnormal posturing, or cranial nerve abnormalities (excluding isolated cranial neuropathies) 3, 1
• Fontanelle examination: Assess for bulging, which suggests increased intracranial pressure 3
• Irritability quality: Inconsolable crying or high-pitched cry may indicate meningeal irritation 1, 4

Cardiovascular Assessment for Myocarditis

• Perfusion status: Capillary refill, peripheral pulses, skin mottling 4
• Respiratory effort: Tachypnea, grunting, retractions suggesting cardiac decompensation 2
• Hepatomegaly: Palpate liver edge as marker of right heart failure
• Heart sounds: Gallop rhythm, muffled heart sounds

Signs of Clinical Instability (LP Contraindications)

• Circulatory shock or respiratory insufficiency: These are absolute contraindications to LP 3
• Coagulation status: Review platelet count (should be ≥100 × 10⁹/L, though ≥50 × 10⁹/L may be acceptable with hematology consultation) 3
• Local skin infection: Examine lumbar puncture site for cellulitis or abscess 3, 1

Critical Laboratory Data to Review Before LP

• Complete blood count with differential: Check for leukopenia (<5000 WBC/mm³), which is highly predictive of bacteremia 5
• Platelet count and coagulation studies: PT/PTT if not already done 3
• Inflammatory markers: CRP and procalcitonin help risk-stratify for bacterial infection 2
• Blood culture status: Confirm drawn before any antibiotics 3, 2
• Trend of liver function tests: Worsening transaminases may suggest viral hepatitis or systemic inflammatory response

Rationale for Proceeding with LP Despite Rhinovirus

Bacterial Co-infection Risk

• Rhinovirus does not exclude bacterial meningitis: Approximately 20% of febrile infants under 90 days have enterovirus, and roughly 50% of enterovirus-positive infants have CSF pleocytosis, but this does not rule out concurrent bacterial infection 3
• Bacterial meningitis prevalence: While only 0.4% of febrile young infants have bacterial meningitis, the catastrophic consequences of missing it mandate CSF evaluation 3, 4
• Blood culture sensitivity limitation: 15-38% of infants with early-onset bacterial meningitis have sterile blood cultures, making CSF analysis essential 3

Age-Specific Risk

• Day 2 of life places this infant in highest-risk category: Neonates under 28 days have the highest risk for invasive bacterial infections with increased morbidity and mortality from delayed diagnosis 2, 4
• Clinical appearance is unreliable: Young infants may have meningitis without classic meningeal signs; well-appearing status does not rule out serious bacterial infection 1, 4

Imaging Considerations Before LP

CT scan is NOT routinely indicated before LP unless specific contraindications are present 3:

• Only obtain CT if GCS <13, new-onset seizures, focal neurological signs (excluding cranial neuropathies), papilledema, or abnormal posturing 3, 1
• In one series of 222 adults with suspected encephalitis, less than 5% had imaging changes suggesting raised intracranial pressure 3
• Routine CT delays diagnosis and is not supported by guidelines for stable infants 3

Echocardiogram Justification

The combination of tachycardia, fever, and elevated LFTs warrants cardiac evaluation:

• Viral myocarditis can present with tachycardia out of proportion to fever
• Rhinovirus is a known cause of viral myocarditis in neonates
• Elevated LFTs may reflect hepatic congestion from right heart failure or systemic inflammatory response
• Echo will assess ventricular function, pericardial effusion, and valve function

Empiric Antibiotic Considerations

If LP is Successfully Obtained Today

• Initiate ampicillin and gentamicin (or ampicillin and cefotaxime) immediately after LP if infant appears ill or has abnormal laboratory findings 3, 4
• Standard dosing: Ampicillin covers Group B Streptococcus and Listeria; aminoglycoside or third-generation cephalosporin covers gram-negative organisms 3

If LP Cannot Be Obtained

• Do not withhold antibiotics if clinical deterioration occurs or if blood cultures return positive 4
• Partially treated meningitis is a significant concern, but untreated bacterial meningitis has higher morbidity and mortality 3

Common Pitfalls to Avoid

• Do not delay LP for unnecessary imaging: CT is only indicated with specific contraindications listed above 3, 1
• Do not assume rhinovirus explains all findings: Viral-bacterial co-infection occurs, and CSF analysis is the only way to exclude bacterial meningitis 3, 1
• Do not rely on normal WBC count: Normal white blood cell count does not rule out bacterial infection, especially in neonates 2, 4
• Do not defer LP based on well appearance alone: Clinical appearance is unreliable in this age group for excluding meningitis 1, 4
• Do not accept traumatic LP as adequate: If CSF is too bloody to interpret, correction factors (500 RBC:1 WBC ratio) should be applied, or repeat LP considered 3

Post-Procedure Management

• Admit for observation regardless of initial CSF results: Neonates under 28 days require hospitalization pending culture results 4
• Repeat CSF analysis in 24-48 hours if initial CSF is normal but clinical suspicion remains high: 5-10% of HSV encephalitis cases have normal initial CSF with negative PCR 3
• Monitor cardiac function closely if echo shows abnormalities: Serial troponins, BNP, and repeat echocardiography may be needed
• Trend LFTs: Worsening hepatic function may indicate progression of viral illness or hemodynamic compromise