Infections of the CNS Flashcards
what might meningococcal disease present with
meningitis
sepsis
or both
what is the most dangerous type meningitis
bacterial meningitis
eg. from meningococcal
what does meningitis mean
inflammation of the meninges
what is classic about meningococcal sepsis
petechial/ purpuric rash- non blanching
does not fade under a glass
Meningococcal bacteria reproduce in the bloodstream and release poisons (septicemia). As the infection progresses, blood vessels can become damaged. This can cause a faint skin rash that looks like tiny pinpricks.
presents in skin all over the body- sign of inflammation in bloodstream not just central nervous system.
what other infections of the central nervous system can you get
encephalitis- inflammation of brain parenchyma
normally viral
why is the purpuric rash so concerning and needs urgent medical care?
it can progress to PURPURA FULMINANS AND GANGRENE
-disordered coagulation
-inflammation in vessels
-severe damage and poor vascular supply
-may need amputation
what are the mortality rates for meningococcal meningitis vs meningococcal sepsis
5-15%
40+%
what are long term complications that affect 20+% of survivors
meningitis
-seizures
-hearing difficulties
-cranial n problems
-focal paralysis
-hydrocephalus
-intellectual disability
-ataxia
sepsis
-limb amputations
-arthritis and join pain
-skin necrosis and scarring
-organ dysfunction, liver, kidney, adrenal glands
what is the definition of sepsis
life threatening organ dysfunction
caused by dysregulated host response to infection
what is sepsis 6
Blood cultures
Urinary output
Fluids
Antibiotics (IV)
Lactate
Oxygen (high flow)
how does infection get there
- BBB
-tightly packed endothelial cells line blood vessels in brain mechanically supported by thin basement membrane. hard to get across
-if breach–> encephalitis
get across by inflammation as cells are close to infectious agents, and become leaky
skull fracture, BBB damaged - blood CSF barrier
-breach–>meningitis - direct
-sinuses
-otitis media
-skull fracture - +2. =haematological spread
how do the barriers in the brain get breached
rare occasions they can traverse barriers= typical inflammatory response
-growing across and infecting cells comprising barrier
-passive transfer in intracellular vacuoles
-carriage across in infected white blood cells
what causes meningits
infection
auto-immune disease
malignancy
what are some common bacteria causing meningitis
Neisseria meningitidis
Haemophilus influenzae
Streptococcus pneumoniae
Mycobacterium tuberculosis
what are some common viruses causing meningitis
ENTEROVIRUSES:
-Echovirus
-Coxsackie viruses A and B
-poliovirus
HERPES VIRUSES
-Herpes simplex 1 and 2
PARAMYXOVIRUS
-complication of mumps
what is a common fungi causing meningitis
Cryptococcus neoformans
what are some common protozoa causing meningitis
Amoeba
Naegleria
Acanthamoeba
the main causative organisms of bacterial meningitis very by age and other risk factors
what is the most common pathogen found in neonates
Escherichia coli
Group B Streptococcus
Listeria monocytogenes
how do you find out what organism is causing meningitis
take csf sample
take blood
what are the most common pathogen found in children under 5 years
Neisseria meningitidis
Haemophilus influenzae
what is the most common type of pathogen found in young adults
Neisseria meningitidis
what are the most common pathogen found in older age group
Streptococcus pneumoniae
Listeria monocytogenes
what are the most common pathogen found in the immunosuppressed
Mycobacterium tuberculosis
Cryptococcus neoformans
why does age matter for working out the organism
gives an idea as to what the organism may be can give treatment straight away while waiting for blood/csf sample results
what are the dangers/ risk factors of neonatal meningitis
early onset
-occurs <7 days
-infected by heavily colonised mother
-premature rupture of membranes
-preterm delivery
-60% fatality rate
most likely to pick up from birth canal- greater risk if birth canal is heavily colonised by bacteria
-bit dependent on mother
late onset
-occurs <3 months
-lack of maternal antibody
-poor hygiene in nursey
-20% fatality rate
Neisseria meningitidis
gram neg. intracellular diplococci
normal in NASOPHARYNX
droplet spread
only infect humans
12+ SEROTYPES
5 PATHOGENIC SEROGROUP STRAINS- A, B, C, W135, Y
why do you want to know serotypes
important in vaccine development
outbreak tracing
is meningococcal meningitis vaccine preventable
yes
vaccines against all major serotypes
Haemophilus influenzae
gram -ve coccobacilli
rod
6 serotypes (a-f)
type B most virulent (Hib)
H influenzae vaccine preventable?
childhood vaccination programme
Streptococcus pneumoniae
gram +ve diplococci
normal in NASOPHARYNX
over 90 bacterial serotypes
common cause of meningitis in young, adults with risk factors (older, diabetic, alcohol xs, asplenic)
is invasive pneumococcal disease vaccine preventable
yes
vaccines against lots of different types of serotypes
eg. PCV13 against 13 commonest serotypes
why do you have to keep monitoring serotypes
most pathogenic get rid of
and another one comes in to fill ecological niche
what are clinical features of babies/ small children with meningitis
they cant report so have to observe
tense/bulging fontanelles
refuse to feed
irritable when picked up, high pitched moaning cry
stiff body with jerky movement
or floppy and lifeless
what clinical features do both septicaemia and meningitis have in common
fever/vomiting
rash anywhere
confused delirious
very sleepy/vacant/difficult to wake
what clinical features are present in meningitis and not septicaemia
severe headache
stiff neck (less common in young)
dislike of bright lights (less common in young)
seizures
what clinical features are common in septicaemia but not meningitis
limb/joint/muscle/pain
cold hands and feet/shivering
pale/mottled skin
fast breathing
what are some diagnostic tests for meningitis
Blood
-U&E, CRP, lactate, glucose
-FBC, clotting
-blood culture, meningococcal and pneumococcal PCR, HIV test
CSF
-protein and glucose
-white cc, gram stain, bacterial culture and pneumococcal PCR, viral pcr tests,
special tests– tb (microscopy, molecular tests, culture) cryptococcal (indian ink, CrAg, fungal culture)
how will the csf fluid collected from a lumbar puncture present
will be inflamed with high protein
low glucose (been consumed by infecting organism)
also high pressure fluid, cloudy (bacterial)
take matched blood and CSF glucose samples
collect enough fluid and some spare
can tell about pathogen by appearance of csf
if antibiotics given before csf hard to tell
when should you delay or omit a lumbar puncture
-risk of bleeding if disordered coagulation
-if raised csf caused because focal neurology suggesting a mass lesion in the brain– brain descend into CSF, blocks of spinal column
-papilloedema– do ct/mri and see what is causing it before lumbar
when do we need CNS imaging
to exclude mass lesions/ oedema– making LP dangerous
if there is a reduction in csf pressure below the lesion this could precipitate herniation of the brainstem or cerebellar tonsils
BRAIN ABSCESS
SUPDURAL EMPYEMA
TUMOUR
NECROTIC SWOLLEN LOBE IN ENCEPHALITIS
what is treatment of bacterial meningitis
main way IV antibiotics (high dose) so crosses BBB
1st try:
HIGH dose Penicillin
HIGH dose Ceftriaxone
maybe with steroids
duration depend on pathogen
eg. pneumococcal longer
how do you prevent bacterial meningitis
Vaccines against:
Haemophilus influenzae b
Pneumococcus
Meningococcus ABCWY
also against:
polio, tetanus
Notify, Prevention, Control
sufficietly dangerous
prophylaxis antibiotics to close contact
discuss viral meningitis
less serious
more common
identify by PCR of CSR
no specific treatment
usually regarded as benign and self-limiting
long term neuropsychiatric sequelae have been described
what is the commonest cause of viral meningitis
HSV-2 commonest cause of viral meningitis
what is Mollaret’s meningitis
recurrent meningitis
might happen with hsv as the viruses can recur
what is the most common cause of encephalitis
Herpes Simplex Virus-1
how is encephalitis different from meningitis
more likely to be confused/drowsy earlier in disease process
encephalitis
symptoms?
investigations?
treatment?
altered cerebration
-confusion, abnormal behaviour, seizures, fever
csf, temporal lobe changes on mri
high dose IV aciclovir
brain abscess
factors?
causes?
pathophysiology?
symptoms?
investigations?
treatment?
invasion on an infection nearby
-otitis media, mastoiditis, sinusitis
often oral nasopharyngeal microbiota
-aerobic (s. aureus, strep. milleri)
-anaerobic (bacteroides sp., fusobacterium sp.)
diffuse inflammation–> focal lesion and pia mater suppuration
headache, focal neurology, seizures
CT/MRI - risk with LP
antibiotics- CEFTRIAXONE AND METRONIDAZOLE
what is the problem of immunocompromised patients and cns infections
They may be at risk from a wider range of pathogens
what is transmissable spongiform encephalopathies
rare prion disease
-proteinacious infectious particles
cause vacuoles and plaques in nervous tissue
highly resistant to heat, chemical agents and irradiation
no treatment, no vaccine
