IC17a PR3151 Meningitis Flashcards
define meningitis
including anatomy
inflammation of the (lepto)meninges
anatomy
meninges consists of three layers - dura mater, arachnoid, pia mater
- leptomeninges consists of the arachnoid and pia mater
what are the causes of meningitis?
1) infection
(a) bacterial: septic meninges
(b) viral: enterovirus, herpes
(c) others: fungal (cryptococci), parasitic (malaria), mycobacterium (TB), syphilis
2) autoimmune diseases
3) drugs
- cotrimoxazole, ibuprofen
what are the risk/predisposing factors for bacterial meningitis?
HCCCNLIS
hospitals check cleanliness confirming no leftover infections spreading
PREDISPOSING FACTORS
Head trauma
CNS shunting
CSF fistula/leak
Congenital defects
Neurosurgical patients
Local infections: otitis media, pharyngitis, sinusitis
Immunosuppressed
Splenectomy
what is the physical signs of bacterial meningitis?
1) kernig sign
2) brudzinski sign
3) bulging fontane (infants)
what is the incidence of meningitis?
more prevalent in females and children
what are the symptoms of bacterial meningitis?
classic triad: headache, backache, neck stiffness
others: photophobia, fever, N/V, chills, anorexia, altered mental status, change in feeding habits (infants),
skin: petechiae, purpura rashes (specific to Neisseria meningitidis)
how to diagnose bacterial meningitis?
1) physical exam
2) blood culture
3) lumbar puncture –> CSF composition, gram stain, culture, PCR.
4) radiology (CT scan, MRI) (optional)
what is the normal CSF composition vs that of bacterial and viral meningitis?
(glucose, protein, WBC)
glucose, protein, WBC
normal:
2.6-4.5 (ratio >0.66)
<0.4
<5/mm3
bacterial meningitis:
very low (ratio <0.4)
>1.5 (high)
>100/mm3 (mostly neutrophils)
viral meningitis
normal to slightly low
normal to slightly high
5-1000/mm3 (mostly leukocytes)
indications for radiology (brain imaging) to determine bacterial meningitis?
optional, usually for:
1) differential diagnosis,
2) complications,
3) prior to lumbar puncture for patients with brain shift due to mass lesion and risk having brain herniation during the procedure.
most likely organism for neonates w/ bact meningitis? include the age range
e coli
strep agalactiae
listeria
most likely organism for infants & children w/ bact meningitis? include the age range
e coli
strep agalactiae
strep pneumo
neisseria
most likely organism for children & adults w/ bact meningitis? include the age range
strep pneumo
neisseria
most likely organism for adults (>50yo) w/ bact meningitis? include the age range
strep pneumo
neisseria
listeria
anerobic gram neg (EKP)
what is listeria monocytogenes?
gram positive intracellular rod
found in water, soil, moist environments
food borne: able to grow and replicate in refrigerator temperature e.g., in cold deli meat, unpasteurised dairy
what is neiserria meningitides
aerobic gram neg diplococci
fastidious, encapsulated
part of normal flora of the nasopharynx
when should empiric tx be started for bact meningitis?
as soon as possible (within 1hour)