Pediatrics · Year 3 · from Pediatrics

Case 2: Bacterial Meningitis

Patient Demographics

  • Age: 8-month-old female
  • Sex: Female

Chief Complaint

"My baby has had a fever and won't stop crying."

History of Present Illness

An 8-month-old female presents with 2 days of fever up to 39.8C, progressive irritability, and decreased feeding. She initially had mild upper respiratory symptoms (runny nose, cough) but over the past 12 hours has become increasingly lethargic and inconsolable. She vomited twice today and has had poor urine output. Parents note that she seems uncomfortable when picked up and arches her back when held. She had been well until this illness and is up-to-date on immunizations through 6 months. She attends daycare.

Growth Parameters

  • Weight: 8.2 kg (50th percentile)
  • Length: 68 cm (50th percentile)
  • Head circumference: 44 cm (75th percentile)

Physical Examination

  • General: Ill-appearing, lethargic, high-pitched cry, difficult to console
  • Vital signs: T 39.5C, HR 180, RR 42, BP 80/50, SpO2 98%
  • HEENT:
  • Anterior fontanelle full and bulging
  • No papilledema visualized
  • Bilateral otitis media (bulging, erythematous TMs)
  • Neck: Unable to assess nuchal rigidity (infant crying)
  • Cardiovascular: Tachycardia, pulses 2+ throughout, cap refill 2 sec
  • Respiratory: Mild tachypnea, clear breath sounds
  • Abdomen: Soft, non-distended
  • Skin: No petechiae or purpura, no rash
  • Neurologic:
  • Lethargic, weak cry
  • Hypotonia
  • Brudzinski sign not assessable
  • Jitteriness noted

Workup

  • CBC: WBC 24,500 (85% neutrophils, 10% bands), Hgb 11.0, Platelets 185,000
  • CMP: Na 133, glucose 95, otherwise normal
  • Blood culture: Obtained
  • Procalcitonin: 8.5 ng/mL (highly elevated)
  • Lumbar puncture CSF analysis:
  • WBC: 2,850/mcL (92% neutrophils)
  • RBC: 50/mcL
  • Protein: 280 mg/dL (elevated)
  • Glucose: 18 mg/dL (serum glucose 95; ratio 0.19, very low)
  • Gram stain: Gram-positive diplococci
  • Culture: Pending
  • CT head (prior to LP given bulging fontanelle): No mass lesion, mild meningeal enhancement

Diagnosis

Bacterial meningitis, likely Streptococcus pneumoniae

Clinical Reasoning

This infant presents with classic signs of bacterial meningitis: fever, irritability progressing to lethargy, bulging fontanelle, vomiting, and CSF findings showing pleocytosis with neutrophil predominance, elevated protein, and markedly decreased glucose (CSF:serum ratio <0.4). Gram-positive diplococci are consistent with Streptococcus pneumoniae, the most common cause of bacterial meningitis in this age group in the post-Hib vaccine era. The concurrent otitis media suggests a potential source of hematogenous spread.

Management

  1. Empiric antibiotics (started immediately):
  • Vancomycin 60 mg/kg/day IV divided q6h (covers DRSP)
  • Ceftriaxone 100 mg/kg/day IV divided q12h
  1. Dexamethasone: 0.15 mg/kg IV q6h x 4 days (started before or with first antibiotic dose to reduce hearing loss risk)
  2. Supportive care:
  • IV fluids (avoid overhydration - risk of SIADH and cerebral edema)
  • Monitor for seizures
  • Frequent neurologic checks
  1. Narrow antibiotics when culture and sensitivities return
  2. Duration: 10-14 days for pneumococcal meningitis
  3. Close contacts: Not required for pneumococcal meningitis (would be needed for meningococcal)
  4. Follow-up:
  • Audiology evaluation before discharge (hearing loss is major complication)
  • Neurodevelopmental follow-up
  • Repeat LP not routinely needed if clinically improving

Clinical Image

Image Description: Gram stain of cerebrospinal fluid demonstrating gram-positive diplococci (lancet-shaped) characteristic of Streptococcus pneumoniae.

Source: CDC Public Health Image Library URL: https://phil.cdc.gov/Details.aspx?pid=2896 License: Public Domain

All cases for this lecture as Markdown