Lecture 18 - Meningitis Flashcards
Name some possible routes of infection for meningitis
> blood borne, parameningeal suppuration e.g. otitis media sinusitis
direct spread through defect in the dura (post surgery/ trauma)
direct spread via cribiform plate
Name some complications of meningitis
death, subdural collection, cerebral vein thrombosis, hydocephalus, deafness (Hib) in kids, convulsions, visual/motor/ sensory deficit
Name the common bacteria causing meningitis
neisseria meningitidis - children/young adults
streptococcus pneumoniae - elderly / young children
which bacteria can be found in foods such as unpasturised cheese
listeria monocytogenes
Why is bacteria in the CSF a greater concern than if bacteria was in the blood
no proteins ( low compliment )
low igG
no lymphatics
only lipophilic compounds through the blood brain barrier
describe the inflammatory process associated with meningitis
1) endotoxin released by Gr -ves and lipotechoic of Gr +ves - trigger inflammatory cascade (TNF INL PAF NO)
2) neutrophils migrate to CSF and release o-
3) free rads damage vascular endothelium alter BBB permeability
Symptoms of meningitis and physical signs
- headache, neck and back stiffness, nausea and vomiting, photophobia
- fever, petechial rash (usually meningococcal)
- kernigs sign (leg at right angles), brudzinskis sign (flexion neck causes leg flexion), neck stiffness (cant put head on chest)
name some other conditions with similar symptoms of meningitis
UTI, dysentery, sub arachnoid haemorrhage, NSAIDs
Name some symptoms of meningitis in infants
flaccid, bulging fontanelle (increased ICP), fever and vomiting, strange cry and convulsions
What is the most rapid diagnostic test for meningitis? what does it show?
lumbar puncture, can distinguish between viral and bacterial
What is the risk of a lumbar puncture in the diagnosis of meningitis?
herniation of brain! if raised intracranial pressure and longer history of symptoms (focal neurology and drowsy)
When examining CSF whats distinctive about 1) bacterial meningitis 2) TB meningitis 3) viral meningitis
1) bacterial high polymorphs (neutrophils) and low glucose
2) TB high lymphocytes and low glucose
3) high lymphocytes
What are the complications of menningococcal disease
- death 13% higher if sepsis 40%.
- necrotic lesions and reactive arthtiris (around purpura rash)
- serositis, neurological and access formation both RARE
complications alter with serogroup type
Name the risk factors for poor outcomes with meningitis
- positive blood cultures
- sinusitis or otitis media
- old age
- low CSF (low white cell count)
- thrombocytopenia
- tachycardia
- absense of rash
- low GCS
How would you manage meningitis (5)
- antibiotics
- oxygenation
- prevent hypoglycaemia and hyponatraemia
- anticonvulsants
- decreased ICP
Name two things an antibiotic against meningitis needs to be
- bacteriacidal
- be able to penetrate the BB to CSF at non-toxic doses
What helps CSF penetration
high lipid solubility, low molecular weight, low ionisation, high serum concentration, low protein binding, meningeal inflammation
1) Give an example of an antibiotic that penetrates meninges at standard dose
2) Why cant many of these be used?
1) chloramphenicol, metronidazole
2) high resistance
which antibiotics penetrate inflamed meninges or at high doses
benzylpenicillin and cephalosporins
1) which antibiotics penetrate the BBB poorly
2) when are they used?
1) gentamycin
2) neonates as BBB isnt as developed
1) Why is choramphenicol effective as meningitis treatment?
2) why isnt it used as first line meningitis ?
3) When would you use it?
1) v good penetration into CSF, activity against organisms which cause meningitis
2) - resistance in Hib and pneumococc
- bad side effects (aplastic anaemia, grey baby syndrome)
3) reserve agent for allergic patients
1) Why is ceftoaxime and ceftriaxone used as first line antibiotic treatment for meningitisin adults and children
2) how often are each given
1) - activity against organisms which cause meningitis
- activity against penicillin resistant pneumococci and Hib
- well tolerated
- good penetration into CSF
2) Cefotax 6 hourly Ceftriax 12 hourly
Which is the most active agent for pneumococcal meningitis?
benzylpenicilin (BUT increased incidence of low and high level resistance in pneumococci)
Why isn’t benzylpenicillin used as first line for meningitis?
as its narrow spec -don’t use until know causative organism and what sensitive to
What would affect antibiotic choice for meningitis?
- age
- clinical risks
- history of allergies
- gram results
- local and national sensitivity data
what else could be prescribed to reduce long term morbidity in children with meningitis? one negative?
sterioids (dexamethasone)
BUT risk of GI bleed
Which meningitis strains are covered in the conjugated vaccine given to babies? which other vaccines are available?
- Hib and men C
- meb B and polyvalent pneumococcal one
When is chemoprophylaxis used in meningitis
secondary cases in close contacts and household of meningococcal and hib
- rifampicin and cipro clear nasopharyngeal carriage
What is the presentation of a brain abscess
focal neurological signs, raised ICP, headache, fever (variable), raised CRP and ESR
Name three ways a brain abscess could be acquired
- direct spread from venous e.g. ear + sinus infection
- haematogenous spread through blood from e.g. endocarditis
- direct implantation e.g. trauma surgery
what bacteria are responsible for brain abscess ?
- strep milleri (from resp flora - cause other abscesses), anaerobes, enterobactiacae, s aureus, polymicrobials
- usually more than one organism
WHich bacteria does chloramphenicol not cover?
listeria
Why do you have to use benxypenicillin and cphalosporins and such a high doses
much less penetrative of BBB than choramphenicol
if an organism is not isolated in gram stain of CSF, but a patients CSF and clinical findings are consistent with bacterial meningitis what do you prescribe
7-14 days ceftoazime or ceftriazone iv
if you suspect brain abscess then what must you do?
CT scan NOT lumbar puncture as raised ICP
Likely cause of multiple brain abscess?
frontal brain abscess? temporal?
1) haematogenous
2) venous from sinus
3) venous from ear
Name two types of surgical management of brain abscesses and when they are indicated
drainage via 1) burr hole 2) craniotomy (if post traumatic or multinoculated or in posterior fossa)
Describe the medical treatment of brain abscesses (not surgical) and how long ? determined by?
Abx -alone if neurology intact. got to know organism and source and
can only do alone if under 1.5cm
high dose ABX for 6-8 weeks 3 w i.v. then 3-5 w oral
clinical and radiological response and surgical intervention
