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)
empiric tx for neonates w/ bact meningitis?
ceftriaxone + ampicillin
- ceftriaxone for strep agar and e coli cover
- ampicillin for listeria cover
empiric tx for infants & children w/ bact meningitis?
ceftriaxone + vancomycin
- vancomycin for s pneumonia cover
- ceftriaxone for neiserria
empiric tx for children and adults w/ bact meningitis?
ceftriaxone + vancomycin
- vancomycin for s pneumonia cover
- ceftriaxone for neiserria
empiric tx for adults >50 w/ bact meningitis?
ceftriaxone + vancomycin + ampicillin
- vancomycin for s pneumonia cover
- ceftriaxone for neiserria cover
- ampicillin for listeria cover
what is the duration of tx for culture directed (strep pneumo) in bact meningitis?1
10-14
what is the duration of tx for culture directed (neisseria meningitidis) in bact meningitis?
5-7
what is the duration of tx for culture directed (listeria monocytogenes) in bact meningitis?
≥21
what is the duration of tx for culture directed (strep agalactiae or grp B strep) in bact meningitis?
14-21
what is duration of tx for culture negative bact meningitis
atleast 14 days, depending on condition of the patient
what is the adjunctive tx for bacterial meningitis?
include indication, dose, and counselling
ADJUNCTIVE CORTICOSTEROID (dexamethasone)
recommended for patients above the neonatal age (after 6 wks)
administer 10-20min before or at same time as first abx dose
10mg Q6h x 4 days
stop if
- confirmed not bact meningitis
- bact meningitis is not due to haemo influ OR strep pneumo
what are the benefits of adjunctive tx for bacterial meningitis?
Less hearing loss and other neurologic sequelae in H. influenzae and S. pneumoniae meningitis
Decreased mortality in S. pneumoniae meningitis
what are the risks of adjunctive tx for bacterial meningitis?
May decrease antibiotic penetration from reduced inflammation caused by CSC.
ADR –mental status changes, hyperglycemia, hypertension
bacterial meningitis therapeutic monitoring steps (step4)
usually improve in 48 hours
otherwise do brain imaging to detect cerebrovascular complications e.g., stroke, brain abscess
check ADR
mortality in bacterial meningitis and long term counselling
patients at high risk of long term neurological and neuropsychological deficits that impair QOL
e.g., focal neuro deficits leading to hearing impairment, cognitive impairment, seizures
what are some of the dosing regimens?
max dose (highest dose, lowest frequency) based on abx table
not found:
PEN G: 4MU Q4H
Rifampicin: 300mg Q12H
Linezolid: 600mg Q12
Vancomycin:
- loading dose = 25-30mg/kg
- maintenance = 15mg/kg Q8-12H for AUC/MIC 400-600
what is the chemoprophylaxis for close contacts in bact meningitis
The risk of meningococcal disease is increased 400–800-fold in individuals in close contact with meningococcal disease, with the highest risk for household contacts
For close contacts (household or day care) and exposure to oral secretions of index case
1) Rifampicin
Adults: 600 mg every 12 hours, four doses
Children: 10 mg/kg every 12 hours, four doses
Infants (younger than 1 month): 5 mg/kg every 12 hours, four doses
2) Ciprofloxacin 500 mg orally, one dose (adults only)
3) Ceftriaxone 125–250 mg intramuscularly, one dose
what specific ABX covers Neisseria? (rationale)
ceftriaxone
but also a cover for strep agalactiae and strep pneumo
what specific ABX covers Listeria? (rationale)
ampicillin
why is vancomycin used for meningitis
it is effective against penicillin-resistant strep pneumo in meningitis
penicillin-resistant and cephalosporin-resistant in culture directed (add on rifampicin)
treatment for meningitis should be what dosage form
all iv dosage form
ceftriaxone use in meningitis?
generally used as an alternative to penicillins for strep pneumo, neiserria, strep agal for culture directed therapy
what is the first line agent to all 4 types of pathogens? (assuming no ___ resistance)
IV pen G or ampicillin
what is the alternative penicillin-resistant agent for listeria?
IV cotrimoxazole OR meropenem
what drugs to avoid for bacterial meningitis? and why to avoid
cefepime and imipenem at high dose will cause seizures
e.g., cefepime in dialysis patients = dose to control aggressively.
what is the alternative penicillin-resistant agent for strep pneumo?
1) ampicillin or penG
2) ceftriaxone
3) vancomycin + rifampicin
write down the entire culture directed therapy regimen
Streptococcus pneumoniae
1)Penicillin susceptible: Penicillin G or Ampicillin
2) Penicillin resistant, cephalosporin susceptible: Ceftriaxone Penicillin,
3) Cephalosporin-resistant: vancomycin plus rifampicin
10 - 14
Neisseria meningitidis
1) Penicillin susceptible: Penicillin or Ampicillin
2) Penicillin-resistant or mild allergy: Ceftriaxone
5-7
Listeria monocytogenes
1) Penicillin G or Ampicillin
2) Penicillin allergy: co-trimoxazole, meropenem
≥ 21
Group B streptococcus (Streptococcus agalactiae)
1) Penicillin or Ampicillin
2) Penicillin, mild allergy: Ceftriaxone
14 - 21
