10.1 Pediatric Bacterial Meningitis, Encephalitis & Focal Intracranial Infections

Pediatric Bacterial Meningitis, Encephalitis and Focal Intracranial Infection

Recognize the Syndrome and Stabilize

Bacterial invasion of the meninges can trigger inflammation, cerebral edema, seizures and impaired perfusion. Neonates may have temperature instability, poor feeding, apnea or lethargy with little neck stiffness. In older children, fever, headache, neck stiffness and altered responsiveness raise concern. Purpura with shock can signal meningococcemia. Persistent altered behavior or consciousness with seizures or focal findings raises concern for encephalitis. A focal deficit after sinusitis, otitis or mastoiditis can also indicate an abscess or empyema.

Assess and support airway, ventilation and circulation and treat shock, hypoglycemia or ongoing seizures immediately. Draw blood cultures promptly if this can be done without delaying empiric IV therapy. Obtain CSF first only when LP is safe and can be done promptly. If imaging, stabilization or procedural assessment would delay it, give treatment first and reassess LP as soon as it is safe. WHO meningitis guideline · NICE meningitis guideline

When to Defer LP

• Suspected mass effect or evolving herniation warrants urgent imaging and specialist assessment. Look for a new focal deficit, focal seizure or posturing, abnormal pupils, papilledema, or rapidly declining consciousness. NICE uses GCS 9 or less or a progressive or rapid decline as an imaging and deferral flag. Routine screening CT is unnecessary in a stable child without risk features. An isolated bulging fontanelle calls for assessment of the full clinical picture. By itself it does not establish mass effect or automatically preclude LP. A normal CT alone does not clear a child with persistent clinical red flags for LP. Pediatric LP guideline
• Stabilize an unprotected airway, respiratory compromise, shock or uncontrolled seizures before LP. Avoid puncturing through infected skin. Extensive or rapidly spreading purpura calls for reassessment of bleeding risk and stability.
• Assess bleeding, coagulation, platelet count, medications and local procedural policy. The 2025 AABB/ICTMG guideline recommends platelet transfusion below 20,000/µL for patients undergoing LP. This is a transfusion threshold. It does not establish that LP is safe at or above that count when other risks are present. For elective LP in critically ill children, Pediatric TAXI-CAB found uncertain benefit from prophylactic platelet transfusion between 20,000 and 50,000/µL. NICE · AABB/ICTMG · Pediatric TAXI-CAB

When LP is safe, select a low lumbar interspace below the conus using age-appropriate landmarks and local technique. Offer analgesia. An urgent diagnostic procedure or empiric therapy should not be postponed solely for a topical anesthetic to take effect. Pediatric LP guideline

Interpret CSF in Context

Send cell count and differential, protein, glucose with a paired blood glucose, Gram stain and culture, plus pathogen-directed PCR as indicated. Use age-appropriate reference values. One pediatric cohort found 95th-percentile CSF WBC counts of 19/µL at 0–28 days and 9/µL at 29–56 days. Protein reference values also fall with age. These are cohort reference estimates. CSF WBC cohort · CSF protein cohort

Worked example. A CSF glucose of 16 mg/dL and paired blood glucose of 110 mg/dL yield a ratio of 16 ÷ 110 ≈ 0.15. Together with marked neutrophilic pleocytosis, protein 285 mg/dL and gram-positive diplococci, this strongly suggests pneumococcal meningitis while culture is pending. A negative Gram stain or PCR panel cannot exclude all bacterial causes. Antibiotics can reduce culture yield within hours and may raise CSF glucose or lower protein. Fixed WBC corrections for a bloody tap can miss disease, especially in neonates. Interpret the original count, differential, cultures and clinical picture together. Pretreatment and culture · Pretreatment and CSF profile · Neonatal traumatic LP study

Empiric Therapy and Narrowing

Ceftriaxone is contraindicated in premature neonates up to a postmenstrual age of 41 weeks, in hyperbilirubinemic neonates, and in neonates 28 days or younger who require or are expected to require IV calcium. Some pathways allow carefully selected neonates to receive it if label and institutional criteria are met. Narrow by organism, meningitis susceptibility breakpoints and response. Typical uncomplicated courses are about 5–7 days for meningococcus, 7–10 for Hib and 10–14 for pneumococcus. Neonatal GBS, gram-negative infections and complications require organism-specific specialist plans. UCSF pediatric meningitis · UCSF pediatric dosing · Ceftriaxone label · IDSA healthcare-associated guidance · Pediatric organism-specific durations

Dexamethasone. In an eligible older infant or child with strongly suspected bacterial meningitis, consider adjunctive dexamethasone under the local pathway, ideally before or with the first antibiotic dose. Never delay antibiotics for it. A pediatric regimen is 0.15 mg/kg IV every six hours. UCSF advises against routine pediatric use, whereas NICE advises IV dexamethasone for strongly suspected or confirmed cases above three months. Hearing benefit is best established for Hib. Some guidelines continue treatment for Hib or pneumococcus for up to four days and stop it for other organisms. Age cutoffs and advice when the first dose is missed vary. Seek infectious disease advice for young infants or late consideration. Arrange hearing assessment and follow-up after bacterial meningitis. Pediatric randomized trials · UCSF · WHO · NICE

HSV Encephalitis and Focal Infection

Start IV acyclovir promptly when HSV encephalitis is suspected. Temporal or frontal MRI abnormalities and focal seizures can support suspicion, especially beyond the neonatal period. CSF red cells or a temporal EEG abnormality may occur but are neither required nor diagnostic. Send CSF HSV PCR when safe. For a compatible encephalitis syndrome with an early negative result, continue empiric treatment and consider repeating CSF PCR in 3–7 days, with timing individualized in neonates. In a neonate with suspected CNS HSV, a common starting regimen is 20 mg/kg IV every eight hours, adjusted for renal function and maturity. Confirmed neonatal CNS disease requires at least 21 days and repeat CSF HSV PCR near completion. Continue IV therapy if still positive. Follow with oral suppression, typically 300 mg/m² per dose three times daily for six months. Older children require age-specific dosing and duration. For example, UCSF uses 15 mg/kg IV every eight hours from 3 months to under 12 years and 10 mg/kg every eight hours at 12 years or older for HSV encephalitis, with renal adjustment, and uses a 21-day course. Infuse over at least an hour and maintain adequate hydration while monitoring kidney function. IDSA encephalitis · UCSF neonatal HSV · UCSF older pediatric HSV · IV acyclovir label · Suppression trial

For suspected brain abscess or subdural empyema, prioritize contrast-enhanced MRI with diffusion imaging when feasible and obtain urgent neurosurgical and infectious disease consultation. With suspected mass effect, defer LP. A community-onset regimen commonly includes a third-generation cephalosporin plus metronidazole. Some U.S. pathways initially add vancomycin, with narrowing according to cultures and source. Drainage or aspiration provides source control and microbiologic samples when indicated. ESCMID abscess guideline · UCSF intracranial abscess pathway

Precautions and Contact Management

Use Standard plus Droplet Precautions for suspected or confirmed meningococcal disease or Hib meningitis until 24 hours after effective therapy begins. Notify public health as required. For meningococcal disease, provide chemoprophylaxis for eligible close contacts regardless of vaccination, ideally within 24 hours of identifying the case. Household, childcare and direct oral secretion exposures can qualify. Select rifampin, ceftriaxone or another approved regimen with public health based on age, contraindications and local ciprofloxacin resistance. For invasive Hib, CDC recommends rifampin for all household contacts when an incompletely vaccinated child younger than four or an immunocompromised person younger than 18 lives in the household. In childcare, CDC recommends it when at least two invasive Hib cases occur within 60 days and underimmunized children attend. CDC isolation table · CDC meningococcal surveillance · CDC Hib surveillance