Bacterial Meningitis

Question 1

Common causative organisms

Answer 1

N. Meningitis
H. Influenza
L.monocytogenes
Group B strep
Streptococcus pneumonia

Question 2

Risk factors for bacterial meningitis

Answer 2

Age- infants particularly those younger than 1 month
Settings of high population and contact with peers
Weakened immune system- cancer , DM, HIV/AIDs
Head trauma
Cochlear implants or CSF shunts
Medical conditions- sinusitis, otitis media, pneumonia, meningococcal disease
Endemic areas

Question 3

Signs and symptoms

Answer 3

Fever
N/V
Photophobia
Altered mental status
Positive kernig or brudzinski signs
Young children- purpuric rash, convulsion, bulging fontanelle

Question 4

Pathophysiology of BM

Answer 4

Nasopharyngeal colonization
Bacteria then phagocytized into hosts bloodstream some CNS bacterial pathogen have extensive capsules resistant to neutrophil phagocytosis.
Activation of host inflammatory response ie macrophage release cytokines , TNF, IL-1 . The release of macrophages trigger proteolytic products and toxic o2 radicals cuz alterations BBB. Platelets activating factor activate coagulation and arachidonic acid metabolites stimulate vasodilation.
Finally we see increased intracranial pressure, decrease cerebral blood flow, cerebral edema and ischemia

Question 5

Bacterial meningitis score

Answer 5

Parameters
Positive CSF gram stain
Presence of seizures
Serum absolute neutrophil count >10 x 10^9 /L
CSF protein > 80mg/dL
CSF neutrophil count > 1000cells/mm^3

Treat if score more than 1

Question 6

CSF fluid analysis do BM

Answer 6

WBC less than 5
Differential : bacterial( neutrophil)
Protein; less than <0.5g\L
CSF:blood glucose ratio between 0.5-0.6

Question 7

Diagnostic tools

Answer 7

Gram stain and culture of CSF
PCR for S. Pneumonia , N. Meningitis, H influenza type B
Rapid antigen test when gram stain is negative

Question 8

Use of dexamethasons for BM

Answer 8

Acts as anti-inflammatory agent
Prevents complications such as hearing loss , neurological deficits of death
Preferred IV/IM for duration of 4 days

Question 9

For infants if S. Pneumonia, N meningitis and H. Influenza give recommended therapy with alternative

Answer 9

S. Pneumonia-vancomycin +3rd gen cephalosporins. alternative ~FQ and meropenem
N. Meningitis- 3rd gen ceph. Alternative-PenG, ampicillin ,FQs
H. Influenza- 3rd gen ceph alternative- chloramphenicol, cefepime and FQs