Meningitis

• Bacterial

• Viral ( aseptic)

• TB

• Fungal

• Chemical

• Parasitic

• ? Carcinomatous

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

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

MeningitisPapilledema

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

• Obtain blood cultures and give empiric antibiotics if LP is delayed

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

Meningitis• Conclusion

– Meningitis is an infectious disease emergency

– Mortality is often high but can be prevented with appropriate medical therapy

– If you consider meningitis in your differential, you are committed to an LP and empiric antibiotics