Meningitis Flashcards
def
inflammation of the leptomeningeal (pia mater and arachnoid) coverings of the brain
most commonly by infection
aetiology
infection:
1 bacterial
2 viral
3 fungal
what are common bacterial causes of meningitis in neonates
group B strep
E. coli
listeria monocytogenes
what are common bacterial causes of meningitis in children
haemophilus influenzae
neisseria meningitidis
streptococcus pneumoniae
what are common bacterial causes of meningitis in adults
neisseria meningitidis (meningococcus)
streptococcus pneumoniae
TB
what are common bacterial causes of meningitis in the elderly
streptococcus pneumoniae
listeria monocytogenes
what are the viral causes of meningitis
enteroviruses (nonpolio)
CMV
HSV
what are the fungal causes of meningitis
cryptococcus (associated with HIV infection)
what are enteroviruses
four groups of enteroviruses 1 polioviruses 2 Coxsackie A viruses 3 Coxsackie B viruses 4 echo viruses
what are the risk factors
close communities basal skull fractures sinusitis inner ear infections alcoholism immunodeficiency/splentectomy intracranial surgery
epi
common with foreign travel to Haj or Africa
history
should include questioning on foreign travel + exposure to rodents, ticks, mosquitoes etc
1 early features -headache 2 later features -neck stiffness -photophobia
examination
1 signs of meningism
2 signs of infection
what are the features of meningism
neck stiffness or aching
photophobia
kernigs sign positive
what is kernigs sign
pain + resistance on passive knee extension with hip fully flexed
what are the features of infection in meningitis
fever
tachycardia + hypotension
decreased consciousness
what is the characteristic feature of meningococcal septicaemia
petechial rash which is non-blanching
investigations
1 bloods
-one for bacteria, one for virology
2 CT scan
-exclusion of mass lesion or increased ICP
3 lumbar puncture
4 staining of petechiae scrapings may detect meningococcus in 70%
why must a CT scan be done before a lumbar puncture
mass lesion or increased ICP may lead to cerebral herniation during subsequent CSF removal
when must a CT scan be done before a lumbar puncture
if GCS <15
suspected raised ICP
symptoms of focal neurology
papilloedema
what is the normal opening pressure in a lumbar puncture
7-18cm
what is the opening pressure in a lumbar puncture with meningitis
can be >40cm
but will typically be raised
what are typical findings of a bacterial meningitis on LP
cloudy CSF
raised neutrophils, protein
decreased glucose
what is the ratio of CSF glucose to plasma glucose in bacterial meningitis
<0.5
what are typical findings of viral meningitis on LP
clear/cloudy CSF
raised neutrophils, protein
normal glucose
what are typical findings of TB on LP
fibrinous CSF
raised lymphocytes, protein
low glucose
what is the ratio of CSF glucose to plasma glucose in viral meningitis
> 0.5
management
1 immediate IV/IM antibiotics 2 IV dexamethasone 3 resuscitation -managed in ITU -vaccination against meningococcal serogroups A +C -notify public health services
when are antibiotics started in meningitis
started when meningitis is suspected, can be before confirmation with CT/LP
what antibiotics are given in meningitis
<55yrs: cefotaxime
>55yrs: cefotaxime + ampicillin (if listeria)
what is the benefit of dexamethasone
continued in pneumococcal or h. influenzae as decreases deaths in s. pneumoniae and decreases hearing loss in h. influenzae
when should dexamethasone not be used
in HIV infection
what is the most common meningococcal serogroup in the UK
serogroup B
complications (5)
septicaemia shock DIC renal failure peripheral gangrene
what is waterhouse friderichsen syndrome
compication of meningitis
bilateral adrenal haemorrhage
prognosis
bacterial meningitis has high mortality
viral meningitis is self limiting
what are the common organisms which cause meningitis in 0-3months
group B strep (most common)
e coli
listeria monocytogenes
what is group b strep
streptococcus agalactiae
what are the common organisms which cause meningitis in 3months-6yrs
Neisseria meningitidis
Streptococcus pneumoniae
Haemophilus influenzae
what are the common organisms which cause meningitis in 6-60yrs
Neisseria meningitidis
Streptococcus pneumoniae
what are the common organisms which cause meningitis in >60yrs
Streptococcus pneumoniae
Neisseria meningitidis
Listeria monocytogenes
what are the common organisms which cause meningitis in the immunocompromised
listeria monocytogenes
- A 22 year old university student comes in with a headache, neck stiffness and photophobia. You are such a pro that you clinically diagnose him with meningitis. Which is the most common form of meningitis in a patient of his age?
Bacterial meningitis due to Haemophilus influenzae
Bacterial meningitis due to Neisseria meningitides
Bacterial meningitis due to Streptococcus pneumoniae
Fungal meningitis
Viral meningitis
Viral meningitis
2. What investigation do you think is most likely to give you the diagnosis of meningitis? Bloods CT scan Lumbar puncture MRI scan Ultrasound scan
Lumbar Puncture
3. You are given the following results of the lumbar puncture. The appearance of the fluid is clear, there is raised protein and normal glucose. Lymphocyte count is raised. What is the most likely cause now? Bacterial meningitis Drug-induced meningitis Fungal meningitis TB meningitis Viral meningitis
Viral meningitis
what are common bacterial causes of meningitis in children
strep pneumoniae
neisseria meningitidis
haemophilus influenzae type B
what are common bacterial causes of meningitis in adults
strep pneumoniae
neisseria meningitidis
what are common bacterial causes of meningitis in elderly
streptococcus pneumoniae
neisseria meningitidis
listeria monocytogenes
what are bacterial causes of meningitis in neonates
group B strep
e coli
listeria monocytogenes
what sort of bacteria is streptococcus pneumonia
gram +ve cocci
what sort of bacteria is neisseria mengitides
gram -ve diplococci
what causes listeria monocytogenes in neonates and elderly
cheese/milk
alcohol
what is associated with group B strep causing meningitis in neonates
extended labour
infection in previous pregnancy
what causes a non-blanching purpuric rash in meningitis
meningococcal septicaemi
what is the most important investigation in meningitis
LP
what are features of bacterial meningitis on LP
turbid
very high (neutrophils)
very high protein
low glucose
what are features of viral meningitis on LP
clear/cloudy
high (lymphocytes)
high protein
normal glucose
what are features of TB/fungal meningitis on LP
clear/cloudy
high (lymphocytes)
high protein
low glucose
what is the management for meningitis for adults
ceftriaxone +/- dexamethasone
