Community Acquired Bacterial Meningitis Secondary to Streptoccocus pneumoniae 1/7/2019

Jihong presented a case of a 57yo woman with no medical history, who was in her usual state of health until 2 weeks ago when she started complaining of a sore throat. The day prior to presentation, the patient’s roommate saw her “sleep walking” and not acting like herself. When her cousin saw her, she immediately brought her to the hospital because the patient was becoming increasingly more confused and agitated. She was ultimately diagnosed with bacterial meningitis secondary to strep pneumo.


Acute Bacterial Meningitis

Epidemiology

  • Developed Countries
    • Community acquired
      • Streptococcus pneumoniae (most common)
      • Neissseria meningitidis
      • Listeria monocytogenes (age > 50, immunodeficiency)
      • H. influenzae Type B: less likely given HiB immunization but rates of vaccination are declining…
    • Healthcare acquired
      • Associated with neurosurgery (i.e. drains), skull trauma.
      • Usually staphylococci and GNR
    • Risk factors
      • HIV
      • Immunosuppression
      • Diabetes
      • EtOH
      • Asplenia (encapsulated organisms, H.influ, strep)

Presentation

  • Usually quite acute and patients are usually ill appearing
  • Headache (usually generalized, severe, seen in most patients) + Classic Triad:
    • Fever (95%, often > 38, others might be hypothermic)
    • Nuchal rigidity (Also present in most patients, 88%)
    • Encephalopathy (78%)
  • Only 44% of patients will have all 3 triad
  • More variable and subtle presentation the older you get
  • Other findings
    • Seizures (inc risk in Listeria)
    • CN palsies (inc risk in Listeria)
    • Cerebral infarction
    • Papilledema
    • Petechial rash, arthritis (Neisseria meningitidis)

Diagnosis

  • Physical Exam: Brudzinski and Kernig: Not sensitive at all but quite specific. Jolt accentuation is more sensitive but less specific (horizontal rotation of the head 2-3 times per second causing a headache) but overall still quite poor in terms of both.
  • Clinical history
  • LP
    • Low glucose
    • High WBC, usually 1k – 5k, typically > 80% neutrophils
    • Protein > 200mg/dL
    • Glucose < 40mg/dL, or CSF:serum glucose ratio of < 0.4, the lower the worse)
    • 99% PPV if any one of these are present: CSF glucose < 34, protein above 220, and WBC > 2000
    • Some data suggesting using CSF lactate
      • WBC can be falsely elevated in traumatic tap or underlying head trauma (i.e. prior SDH)
      • Correction for traumatic tap: subtract 1 WBC for every 500-1500 RBC in the CSF, just use 1000 to remember easier.
    • Blood + CSF cultures
  • When to CT first
    • Do CT first if the patient has the following:
      • Focal neuro deficits
      • Papilledema
      • Immunocompromised (HIV, transplant, etc)
      • H/o CNS mass, stroke, focal infection
    • Otherwise, ok to go straight for the LP, but LP is contraindicated (but not absolute) under these circumstances:
      • PLt < 50
      • INR > 1.4
      • Lovenox, please hold at least 12 hours in advance
      • Paraspinal abscess

Management

  • Empiric antibiotics, should not wait after LP to start!
    • Start ASAP, don’t wait for the LP
    • Most community acquired meningitis: Vancomycin and Ceftriaxone (2g Q12H) should suffice
      • Age > 50 adults or immunocompromised: Add ampicillin 2g Q4H for Listeria coverage
      • Community and immunocompromised: substitute CTX with cefepime
      • Healthcare associated: Vancomycin, cefepime or carbapenem class with pseudomonal coverage
      • PCN allergy: Can use Vanc, moxifloxacin, and Bactrim (Listeria coverage)
  • Dexamethasone
    • Studies have shown improved neurological outcome with dexamethasone prior to abx, give dex 10mg IV q6H for 4 days.
    • Start before Abx
    • Also potentially reduces risk of post-infectious neurological complications.
    • Most of the data is from management of pneumococcal meningitis, some have suggested that dex can be DC if another cause is diagnosed.

Prognosis

  • < 60 yo: ~ 17% mortality
  • 37% mortality in > 60
  • Staph aureus: 43% mortality
  • Seizures, focal neuro deficits, coexisting medical conditions, high CSF pressure, older age, coma, low CSF:serum glucose ratio tend to be associated with poor prognosis
  • Post-infectious neurological complications
    • As high as 15-22% in kids
    • Up to 1/3 in adults

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