meningitis Flashcards
causes of meningitis
1) infection
- bacteria: septic meningitis
- virus: enterovirus, herpes
- others: fungal (cryptococci), parasitic (malaria), myco tb, syphillis
2) drugs
- cotrimoxazole
3) autoimmune disease
epidemiology for meningitis
1) male > female
2) more common in children, underdeveloped countries
predisposing factors for meningitis
1) head trauma
2) CNS shunt (direct access)
3) neurosurgical pt
4) CSF fistula/leak
5) local infection
6) immunosuppression
7) splenectomised pt
8) congenital defect
9) prolonged contact w infected pt
10) travel to endemic countries
pathophysiology meningitis
1) predisposing factors -> predispose infection & colonisation by bacteria that cause meningitis
2) causative agents gain entry via
- invasion of mucosal surface (respi tract) -> haematogenous spread to brain
- spread from parameningeal focus (otitis media, sinusitis)
- penetrating head trauma
- anatomic defect in meninges
- previous neurosurgical procedure
3) bacteria enter CNS -> colonise meninges (esp arachnoid) -> bacterial meningitis
causative agent meningitis
1) adult & children
- strep pnuemo, N. meningitidis, H. influenzae
2) immunocompromised/elderly
- strep pneumo, N. meningitidis, listeria monocytogenes, staph aureus
3) neonates
- group B strep (vaginal), E.coli, listeria monocytogenes
4) neurosurgical procedure
- e.coli, klebsiella, pseudomonas
symptom of meningitis
- fever, chill
- classic triad: headache, backache, nuchal (neck) rigidity
- mental status change (irritability), photophobia
- N/V, anorexia, poor feeding habit (infant)
- petechiae/purpura (neisseria meningitidis meningitis)
physical signs of meningitis
1) kernig sign
- backpain when hamstring extended & thigh perpendicular to trunk
2) brudzinski sign
- severe neck stiffness
- neck held up -> natural reflex of hip & knee
3) bulging fontae (infant)
- skull X fused together
lumbar puncture for meningitis
1) glucose
- bacterial: turbid, very low, CSF:blood < 0.4
- viral: clear, normal to slightly low
2) protein
- bacterial: raised > 1.5 g/L
- viral: normal, mildly raised
3) WBC
- bacterial: raised > 100 cells/mmm^3, predominantly neutrophils, pleocytosis
- viral: raised 5-1k cells/mm^3, predominantly lymphocytes
empiric therapy for meningitis based on age groups
1) < 1 month
- ceftriaxone + ampicillin
2) 1-23 month
- ceftriaxone + vancomycin
3) 2-50 yo
- ceftriaxone + vanco
4) > 50 yo
- ceftriaxone + vanco + ampicillin
meningitis culture directed
1) strep pneumo
- pen G
- resistant & cephalosporin susceptible: ceftriaxone
- both resistant: vanco + Rifampicin
- 10 - 14 days
2) N. meningitidis
- pen
- pen resistant/mild allergy: ceftriaxone
- 5-7 days
3) Listeria monocytogenes
- pen G
- pen allergy: cotrimoxazole
- ≥ 21 days
4) Group B strep (agalactiae)
- pen
- pen, mild allergy: ceftriaxone
- 14-21 days
what if culture negative for meningitis
empiric for 14 days, extend according to condition
indication for adjunctive corticosteroid for meningitis
pt symp > 6 wks, dexamethasone
risk benefits of adjunctive corticosteroid for meningitis
benefit
- less hearing loss & other neurologic sequelae
- lower mortality (strep pneumo)
risk
- reduce inflam = decrease Abx penetration
- ADR (mental status change, hyperglycaemia, HTN)
chemoprophylaxis for N. meningitidis
indication: close contact, exposure to oral secretion
short course drugs: rifampicin (Children), cipro (Adult), ceftriaxone
meningitidis morbidity (monitoring)
- focal neurological deficit -> hearing impairment, cognitive impairment, seizure
- high risk long term neurological & neuropsychological deficit that affect QoL
