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Medicine > Infections of the CNS > Flashcards

Infections of the CNS Flashcards

1
Q

what might meningococcal disease present with

A

meningitis
sepsis
or both

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2
Q

what is the most dangerous type meningitis

A

bacterial meningitis
eg. from meningococcal

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3
Q

what does meningitis mean

A

inflammation of the meninges

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4
Q

what is classic about meningococcal sepsis

A

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.

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5
Q

what other infections of the central nervous system can you get

A

encephalitis- inflammation of brain parenchyma

normally viral

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6
Q

why is the purpuric rash so concerning and needs urgent medical care?

A

it can progress to PURPURA FULMINANS AND GANGRENE
-disordered coagulation
-inflammation in vessels
-severe damage and poor vascular supply
-may need amputation

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7
Q

what are the mortality rates for meningococcal meningitis vs meningococcal sepsis

A

5-15%
40+%

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8
Q

what are long term complications that affect 20+% of survivors

A

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

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9
Q

what is the definition of sepsis

A

life threatening organ dysfunction
caused by dysregulated host response to infection

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10
Q

what is sepsis 6

A

Blood cultures
Urinary output
Fluids
Antibiotics (IV)
Lactate
Oxygen (high flow)

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11
Q

how does infection get there

A
  1. 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
  2. blood CSF barrier
    -breach–>meningitis
  3. direct
    -sinuses
    -otitis media
    -skull fracture
  4. +2. =haematological spread
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12
Q

how do the barriers in the brain get breached

A

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

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13
Q

what causes meningits

A

infection
auto-immune disease
malignancy

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14
Q

what are some common bacteria causing meningitis

A

Neisseria meningitidis

Haemophilus influenzae

Streptococcus pneumoniae

Mycobacterium tuberculosis

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15
Q

what are some common viruses causing meningitis

A

ENTEROVIRUSES:
-Echovirus
-Coxsackie viruses A and B
-poliovirus

HERPES VIRUSES
-Herpes simplex 1 and 2

PARAMYXOVIRUS
-complication of mumps

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16
Q

what is a common fungi causing meningitis

A

Cryptococcus neoformans

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17
Q

what are some common protozoa causing meningitis

A

Amoeba
Naegleria
Acanthamoeba

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18
Q

the main causative organisms of bacterial meningitis very by age and other risk factors
what is the most common pathogen found in neonates

A

Escherichia coli
Group B Streptococcus
Listeria monocytogenes

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19
Q

how do you find out what organism is causing meningitis

A

take csf sample
take blood

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20
Q

what are the most common pathogen found in children under 5 years

A

Neisseria meningitidis
Haemophilus influenzae

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21
Q

what is the most common type of pathogen found in young adults

A

Neisseria meningitidis

22
Q

what are the most common pathogen found in older age group

A

Streptococcus pneumoniae
Listeria monocytogenes

23
Q

what are the most common pathogen found in the immunosuppressed

A

Mycobacterium tuberculosis
Cryptococcus neoformans

24
Q

why does age matter for working out the organism

A

gives an idea as to what the organism may be can give treatment straight away while waiting for blood/csf sample results

25
Q

what are the dangers/ risk factors of neonatal meningitis

A

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

26
Q

Neisseria meningitidis

A

gram neg. intracellular diplococci
normal in NASOPHARYNX
droplet spread
only infect humans

12+ SEROTYPES
5 PATHOGENIC SEROGROUP STRAINS- A, B, C, W135, Y

27
Q

why do you want to know serotypes

A

important in vaccine development
outbreak tracing

28
Q

is meningococcal meningitis vaccine preventable

A

yes
vaccines against all major serotypes

29
Q

Haemophilus influenzae

A

gram -ve coccobacilli
rod

6 serotypes (a-f)
type B most virulent (Hib)

30
Q

H influenzae vaccine preventable?

A

childhood vaccination programme

31
Q

Streptococcus pneumoniae

A

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)

32
Q

is invasive pneumococcal disease vaccine preventable

A

yes
vaccines against lots of different types of serotypes

eg. PCV13 against 13 commonest serotypes

33
Q

why do you have to keep monitoring serotypes

A

most pathogenic get rid of
and another one comes in to fill ecological niche

34
Q

what are clinical features of babies/ small children with meningitis

A

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

35
Q

what clinical features do both septicaemia and meningitis have in common

A

fever/vomiting
rash anywhere
confused delirious
very sleepy/vacant/difficult to wake

36
Q

what clinical features are present in meningitis and not septicaemia

A

severe headache
stiff neck (less common in young)
dislike of bright lights (less common in young)
seizures

37
Q

what clinical features are common in septicaemia but not meningitis

A

limb/joint/muscle/pain
cold hands and feet/shivering
pale/mottled skin
fast breathing

38
Q

what are some diagnostic tests for meningitis

A

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)

39
Q

how will the csf fluid collected from a lumbar puncture present

A

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

40
Q

when should you delay or omit a lumbar puncture

A

-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

41
Q

when do we need CNS imaging

A

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

42
Q

what is treatment of bacterial meningitis

A

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

43
Q

how do you prevent bacterial meningitis

A

Vaccines against:
Haemophilus influenzae b
Pneumococcus
Meningococcus ABCWY
also against:
polio, tetanus

Notify, Prevention, Control
sufficietly dangerous
prophylaxis antibiotics to close contact

44
Q

discuss viral meningitis

A

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

45
Q

what is the commonest cause of viral meningitis

A

HSV-2 commonest cause of viral meningitis

46
Q

what is Mollaret’s meningitis

A

recurrent meningitis
might happen with hsv as the viruses can recur

47
Q

what is the most common cause of encephalitis

A

Herpes Simplex Virus-1

48
Q

how is encephalitis different from meningitis

A

more likely to be confused/drowsy earlier in disease process

49
Q

encephalitis
symptoms?
investigations?
treatment?

A

altered cerebration
-confusion, abnormal behaviour, seizures, fever

csf, temporal lobe changes on mri

high dose IV aciclovir

50
Q

brain abscess
factors?
causes?
pathophysiology?
symptoms?
investigations?
treatment?

A

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

51
Q

what is the problem of immunocompromised patients and cns infections

A

They may be at risk from a wider range of pathogens

52
Q

what is transmissable spongiform encephalopathies

A

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

Medicine (54 decks)

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