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Meningitis
• Definition– Bacterial meningitis is an inflammatory response to
bacterial infection of the pia-arachnoid and CSF of the subarachnoid space
• Epidemiology– Incidence is between 3-5 per 100,000– More than 2,000 deaths annually in the U.S.– Relative frequency of bacterial species varies with
age.
Meningitis
• Epidemiology– Neonates (< 1 Month)
• Gm (-) bacilli 50-60%• Grp B Strep 20-40%• Listeria sp. 2-10%• H. influenza 0-3%• S. pneumo 0-5%
Meningitis
• Epidemiology– Children (1 month to 15 years)
• H. influenzae 40-60%– Declining dramatically in many geographic
regions
• N. meningitidis 25-40%• S. pneumo 10-20%
Meningitis
• Epidemiology– Adults (> 15 years)
• S. pneumo 30-50%• N. Meningitidis 10-35%
– Major cause in epidemics
• Gm (-) Bacilli 1-10%– Elderly
• S. aureus 5-15%• H. influenzae 1-3%
– >60 include Listeria, E. coli, Pseudomonas
Meningitis
• Pathogenesis– Majority of cases are hematogenous in
origin
– Organisms have virulence factors that allow bypassing of normal defenses• Proteases• Polysaccharidases
Meningitis
• Pathology and Pathogenesis– Sequential steps allow the pathogen into the
CSF• Nasopharyngeal colonization
• Nasopharyngeal epithelial cell invasion
• Bloodstream invasion
• Bacteremia with intravascular survival
• Crossing of the BBB and entry into the CSF
• Survival and replication in the subarachnoid space
Meningitis
• Pathology– Hallmark
• Exudate in the subarachnoid space• Accumulation of exudate in the dependent areas of the
brain• Large numbers of PMN’s • Within 2-3 days inflammation in the walls of the small
and medium-sized blood vessels• Blockage of normal CSF pathways and blockage of the
normal absorption may lead to obstructive hydrocephalus
Meningitis
• Clinical Manifestations– HA– Fever– Meningismus– Cerebral dysfunction
• Confusion, delirium, decreased level of consciousness
– N/V– Photophobia
Meningitis• Clinical Manifestations – Nuchal rigidity
– Kernig’s• Pt supine with flexed knee has increased pain with passive
extension of the same leg
– Brudzinski’s• Supine pt with neck flexed will raise knees to take
pressure off of the meninges• Present in 50% of acute bacterial meningitis cases
– Cranial Nerve Palsies• IV, VI, VII
– Seizures
Meningitis
• Clinical Manifestations - Meningococcemia– Prominent rash
• Diffuse purpuric lesions principally involving the extremities
– Fever, hypotension, DIC – History of terminal complement deficiency– Classic findings often absent
• Neonates• Elderly
Meningitis
• Diagnosis– Assess for increased ICP
• Papilledema• Focal neurologic findings
– Defer LP until CT scan or MRI obtained if any of above present
– If suspect meningitis and awaiting neuroimaging• Obtain BC’s and start empiric Abx
Obtain CT scan before lumbar puncture in patients with:
• Immunucompromised state • History of CNS disease • New onset seizures • Papilledema • Altered level of consciousness • Focal neurologic signs
LP-CSF
• Tube # 1 Protein & Glucose
• Tube # 2 Gram stain & Culture
• Tube # 3 Cell count & differential
• Tube # 4 Store ( PCR, viral studies etc)
Meningitis
• Diagnosis– CSF Findings : Opening pressure Appearance Cell count & differential Glucose Protein Gram stain & culture
• Opening pressure: high, > 200 mmH20
• Cloudy
• 1000-5000 cells/mm3 with a neutrophil predominance of about 80-95%
• <40mg/dl and less than 2/3 of the serum glucose
• Protein elevated
Meningitis
• Diagnosis– Rapid Tests
• CIE (Counter immunoelectrophoresis/ latex agglut.)
• PCR
– CT/MRI• Little role in DIAGNOSIS of menigitis• Obtain if suspect increased ICP
Meningitis
• Diagnosis– Additional Tests
• CBC w/ diff
• Blood cultures
• CXR
• Electrolytes and renal function
Meningitis
• Differential Diagnosis– CNS infections (abscess, encephalitis)
– Viral/ Tb/ Lyme meningitis
– Ricketsial infections
– Cerebral vasculitis
– Subarachnoid hemorrhage
– Neurosyphilis
Meningitis
• Treatment– Emergent empirical antimicrobial therapy
• Based on age and underlying disease status
– Empiric antibiotic regimines• Neonates (<3 months)
– Ampicillin plus a third generation cephalosporin
• Children– Third generation cephalosporin ( alternative -ampicillin and
chloramphenicol)
• Young adults– Third generation cephalosporin (Ceftriaxone) + Vancomycin
Meningitis
• Treatment– Empiric Antibiotic Regimines
• Older adults– Ampicillin in combination with third generation
ceph.
• Postneurosurgical Pt’s– Vancomycin plus ceftazidime until cultures are
available
Meningitis
• Treatment– N. Meningitidis
• High dose Pen G
– S. pneumoniae• Ceftriaxone• For areas with high level resistance
– Vancomycin plus third generation cephalosporin or rifampin
Meningitis
• Treatment– Gm (-) Enterics
• Third generation cephalosporins
– L. monocytogenes• Ampicillin
– S. aureus• Vancomycin or Nafcillin
– S. epidermidis• Vancomycin
Meningitis
• Treatment– Duration of Treatment
• Dependent on infecting organism– Average of 10-14 days– Gm (-) bacilli for 3 weeks
Meningitis
• Treatment– Steroids
– Shortly before or along with antibiotics. Do not give steroids after antibiotic treatment.
– de Gans J, van de Beek D. Dexamethasone in adults with bacterial meningitis. N Engl J Med. 2002;347:1549-56.
Meningitis• Prognosis
– Pneumococcal Meningitis• Associated with the highest mortality rate
– 20-30%
• Permanent neurologic sequelae– 1/3 of pts
– Hearing loss
– Mental retardation
– Seizures
– Cerebral Palsy
Meningitis
• Vaccinations– Asplenic pts should have had a
pneumoccocal vaccine prior to their splenectomy
– Vaccines available for H. influenza
– Prophylaxis for N. meningitidis contacts• Rifampin