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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
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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 • H.Fever • Neck Stiffness • Meningismus • Cerebral dysfunction • Confusion,, decreased level of consciousness • Nevrit(عصب باصره) • 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
Meningitis Papilledema
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