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Human Disease > Meningitis > Flashcards

Flashcards in Meningitis Deck (108):
1

What was mortality rate for meningitis caused by S pneumoniae, 90yrs ago / today?

90 yrs ago = 98-100%

Today = 40%

2

What was mortality rate for meningitis caused by N meningitidis, 90yrs ago / today?

90 yrs ago = 77%

Today = 10%

3

What was mortality rate for meningitis caused by H influenzae, 90yrs ago / today?

90 yrs ago = 98-100%

Today = 5-10%

4

When was penicillin discovered / on the market?

Discovered - 1928

On the market - 1942

5

What is mortality rate for meningitis now?

S pneumoniae - 40%
N meningitidis - 10%
H influenzae - 5-10%

6

What morbidity is associated with meningitis?

deafness
paralysis
speech issues
epilepsy
neuro-psychiatric issues

7

Who gets meningitis?

neonates
- poorly developed capillaries (not closely knit)
- from flora from mother's birth canal

young & old
- weaker BBB

8

Why do neonates get meningitis?

- poorly developed capillaries (not closely knit)
- from flora from mother's birth canal

9

What are three meninges layers?

dura mater
arachnoid mater
pia mater

10

where is CSF?

subarachnoid space
(between arachnoid and pia mater)

11

What is in subarachnoid space?

CSF (cerebrospinal fluid)
Blood vessels

12

Define meningitis

inflammation of lepto-meningeal membranes
ie dura / arachnoid / pia mater

13

What are 4 main causes of meningitis?

- inflammation
- infection
- parameningeal foci (max sinus, venous plexus)
- neo-plastic / para-neoplastic (ie a consequence of cancer, eg lymphoma)

14

What parameningeal foci can cause meningitis?

- infection in maxillary sinus / venous plexus

15

What is a neoplastic / paraneoplastic cause of meningitis?

a consequence of cancer, eg lymphoma

16

What infectious agents cause meningitis?

Virus - most common
- enterovirus, mumps, herpes
Bacteria - 2nd most common
- meningococci, Pneumococci, H. influenzae
Fungal
- Cryptococus neoformans, Coccidioidomycosis
- NOT usually candida
Parasitic
- Naegleria fowleri, Acanthamoeba spp. (ie amoeba)

17

What viruses cause meningitis?

- enterovirus
- mumps
- herpes

18

What bacteria cause meningitis?

- meningococci
- pneumococci
- H influenzae

19

What fungus causes meningitis?

- Crytococcus neoformans
- Coccidioidomycosis
- NOT candida

20

What parasites cause meningitis?

- Naegleria fowleri
- Acanthamoeba spp

21

How does the blood brain barrier (BBB) work?

closely knit capillaries

22

Where is the likely entry point into the BBB?

choroid plexus - weaker emissary veins (connect the extracranial venous system with the intracranial venous sinuses)

23

What three ways can organisms reach the CSF?

BBB
- bacteraemia / viraemia / parasitaemia
- can enter anywhere, but most likely at choroid plexus
Direct
- chronic infections in cranial bones, ears, sinuses, oral cavity, upper respiratory tract
Neuronal
- infection in peripheral neurons, axonal transport, replication, cell-to-cell spread of infection to connection neurons in CNS
- eg rabies

24

How do organisms causing meningitis DIRECTLY access the CSF?

chronic infections in:
- cranial bones
- ears
- sinuses
- oral cavity
- upper respiratory tract

25

What type of blood infections can cause meningitis?

bacteraemia
viraemia
parasitaemia

26

How does a neuronal infection reach the CSF to cause meningitis?

- infection in peripheral neuron
- axonal transport
- replication
- cell-to-cell spread
- infection passed to connecting neurons in CSF

27

What is the pathogenesis of meningitis?

- mucosal colonisation - eg in sinus / oropharyngeal fossa
- intravascular survival (ie pathogen gets from origin into blood)
- meningeal invasion (through dura and arachnoid mater)
- survival in subarachnoid space
- inflammatory response / increase BBB permeability / cerebral vasculitis
- vessels leaky and blocked, therefore cerebal oedema
- CSF flow disturbances
- increased intercranial pressure
- decreased cerebral blood flow
- loss of cerebro-vascular autoregulation
- coma / death

28

What are the 4 main risk factors for meningitis?

Age
- neonates - close knit capillaries not well dev
- young / old (75+) - weaker BBB

Geography
- overcrowding
- tropical climates - increased organisms, meningitis 'belt ' in Africa

Immunity
- steroids, chemotherapy, HIV

Trauma / post-neurosurgical
- esp base of skull trauma
- Neurosurgery (cerebral shunt, external vascular drain)

29

What are the GEOGRAPHICAL risk factors for meningitis?

- overcrowding
- tropical climates - increased organisms, meningitis 'belt ' in Africa

30

What are the IMMUNITY risk factors for meningitis?

- steroids, chemotherapy, HIV

31

What NUEROLOGICAL SURGERY could cause meningitis?

- cerebral shunts
- external vascular drain

32

Where is worst place to have skull fracture?

Base of skull (base of occipital / temporal bones)
- rare

33

What bacteria commonly cause meningitis in neonates?

Group B streptocuccus
E coli
Listeria
K pneumoniae (NOT S pneumoniae)

34

What bacteria commonly cause meningitis in

S pneumoniae
N meningitidis

35

What bacteria commonly cause meningitis in >50yrs?

S pneumoniae
N meningitidis
Listeria
aerobic gram -ve bacilli

36

What bacteria commonly cause meningitis in immunocompromised?

S pneumoniae
N meningitidis
Listeria
gram -ve bacilli
Pseudomonas aeruginosa

37

What bacteria commonly cause meningitis in basilar skull fracture (base of skull)?

S pneumoniae
H influenzae
Group A beta-haemolytic streptococci

ie oral organisms

38

What bacteria commonly cause meningitis in head injuries / post-neurosurgery?

A aureus
S epidermidis
aerobic gram -ve bacilli
P aeruginosa

ie skin flora

39

What oral organisms can cause meningitis and what type of person is at risk?

S pneumoniae
H influenzae
Group A beta-haemolytic streptococci

Base of skull fracture

40

What skin flora organisms can cause meningitis and what type of person is at risk?

A aureus
S epidermidis
aerobic gram -ve bacilli
P aeruginosa

Head injury / post-neurosurgery

41

Who is at risk of S pneumoniae and N meningitidis meningitis?

50yrs
immunocompromised

42

Who is at risk of S pneumoniae meningitis?

50yrs
immunocompromised
base of skull fracture

43

Who is at risk of N meningitidis meningitis?

50yrs
immunocompromised

44

Who is at risk of H influenzae meningitis?

basilar skull fracture (base of skull)

45

Who is at risk of Listeria meningitis?

neonates
>50yrs
immunocompromised

46

Who is at risk of gram -ve bacilli meningitis?

>50ys
immunocompromised
head injury
post-neurosurgery

47

What are four clinical signs of meningitis?

- fever
- neck stiffness
- altered mental state
- headache / photophobia

48

What % get 3 of 4 signs of meningitis?

44%

49

What % get 2 of 4 symptoms of meningitis?

95%

50

What could fever and headache be a symptom of?

meningitis!

51

What positional tests are there to diagnose meningitis?

Kernig's sign
- lie flat, lift head, if meningitis - knees will bend too

Brudzinski's sign
- lie flat, lift one left 90 degrees in air, if can't straighten leg = meningitis (stiff hamstring)

52

What is Kernig's sign?

- lie flat, lift head, if meningitis - knees will bend too

53

What is Brudzinski's sign?

- lie flat, lift one left 90 degrees in air, if can't straighten leg = meningitis (stiff hamstring)

54

What is sensitivity of Kernig's and Brudzinski's sign?

5% !

55

What is gold std to diagnose meningitis?

Lumber puncture

56

How do you do lumber puncture?

foetal position
insert needle between L3 and L4
collect CSF

57

What are normal CSF values?

- clear appearance
- opening pressure 5-20cm
- cell count

58

What is the opening pressure during a lumber puncture?

The pressure measured in CSF when needle first inserted

Normal = 5-20cm

59

What is
- cell count
- cell type
- glucose CSF : blood ratio
- Protein
levels in CSF in viral meningitis?

- cell count = 50-1000
- cell type = lymphocytes
- glucose CSF : blood ratio >0.45 (ie >45% of blood glucose)
- Protein

60

What is
- cell count
- cell type
- glucose CSF : blood ratio
- Protein
levels in CSF in bacterial meningitis?

- cell count = 1000-10,000
- cell type = neutrophils
- glucose CSF : blood ratio

61

What is
- cell count
- cell type
- glucose CSF : blood ratio
- Protein
levels in CSF in fungal meningitis?

- cell count = 20-500
- cell type = lymphocytes
- glucose CSF : blood ratio 45mg/dL

62

What is
- cell count
- cell type
- glucose CSF : blood ratio
- Protein
levels in CSF in TB meningitis?

- cell count = 50-300
- cell type = lymphocytes
- glucose CSF : blood ratio

63

What is
- cell count
- cell type
- glucose CSF : blood ratio
- Protein
levels in CSF in partially treated meningitis? (ie with antibiotics)

unknown!

64

When should lumber puncture be done?

ASAP
- antibiotics will affect results of CSF

65

What type of meningitis has CSF with:
cell count 750?

Viral

66

What type of meningitis has CSF with:
cell count 300?

viral, TB, fungal

67

What type of meningitis has CSF with:
cell count 9000?

bacterial

68

What type of meningitis has CSF with:
lymphocytes as main cell type?

viral, fungal, TB

69

What type of meningitis has CSF with:
neutrophils as main cell type?

bacterial

70

What type of meningitis has CSF with:

bacterial, TB, fungal

71

What type of meningitis has CSF with:
>0.45 CSF : blood glucose ratio?

viral

72

What type of meningitis has CSF with:
0.5 CSF : blood glucose ratio?

viral

73

What type of meningitis has CSF with:
0.6 CSF : blood glucose ratio?

This is the normal level!

74

What type of meningitis has CSF with:
protein 150mg/dL?

viral (45mg/dL)

75

What type of meningitis has CSF with:
The highest protein?

bacterial (100-500mg/dL)

76

What type of meningitis has CSF which is sterile?

viral

77

What type of meningitis has CSF with:
the highest glucose CSF : blood ratio?

viral (>0.45)

78

What extra tests can be done on CSF?

PCR - Meningococci, Pneumococci
Virology PCR
Antigen test - Cryptococcal Ag, Pneumo latex
India ink - Cryptococci
Fungal cultures - Crytococcus neoformans, Coccidioidomycosis
ZN stain
AFB culture - acid fast bacilli smear and culture - test for TB
Cytology
Oligoclonal bands - bands of Ig seen in CSF after electrophoresis
Xanthochromia - yellow discolouration = bilirubin present (likely subarachnoid haemorrhage)

79

What is a Xanthochromia test?

tests CSF for yellow discolouration = bilirubin present (likely subarachnoid haemorrhage)

80

What is a Oligoclonal bands test?

tests CSF for bands of Ig seen in CSF after electrophoresis

81

What is a AFB culture?

acid fast bacilli smear and culture - test for TB in CSF

82

What can india ink test for?

Cryptococci

83

Is an MRI / CT needed before lumbar puncture?

most people have normal MRI / CT with meningitis
but should do MRI / CT
- exclude other diagnoses
(intracranial haemorrhage, migraine, cerebral tumour)
- all get headaches and neck stiffness

84

Apart from meningitis, what other diagnoses for headaches and neck stiffness?

- intracranial haemhorrhage
- migraine
- cerebral tumour

85

How you do determine if it's meningitis or a haemorrhage?

MRI / CT

86

When should you do neuro-imaging in meningitis?

Before lumbar puncture
If history of unconsciousness
history of seizures
focal neurology (specific area of body affected)
low GCS

87

What is GCS?

Glasgow Coma Scale

88

Where is the inflammation in meningitis?

subarachnoid space mainly

89

Why do you do neuro-imaging (MRI / CT) in meningitis?

if cerebral abcess, then can't do lumbar puncture
- it may rupture and cause hernia

Symptoms of cerebral abcess
- seizures
- focal neurology (specific area of body affected)
- Low GCS (Glasgow Coma Scale

90

What are 4 main complications of meningitis?

Seizures
- scar tissue from infection / inflam = scar epilepsy

Hydrocephalus
- increase in CSF in ventricles, therefore compression of brain
- CSF is thicker (increase cell count), therefore reduced flow, therefore increased risk blockage
- pressure released down and out via foramen magnum (pons compressed = cardiorespiratory arrest)
- rare

Transtentorial herniation
- brain expands inwards, towards pons/brain stem (motor / respiratory centre)
- can cause coma, death

Infarcts
- caused by vasculitis and vascular compression

91

What is Seizure complication in meningitis?

- scar tissue from infection / inflam = scar epilepsy

92

What is hydrocephalus complication in meningitis?

- increase in CSF in ventricles, therefore compression of brain
- CSF is thicker (increase cell count), therefore reduced flow, therefore increased risk blockage
- pressure released down and out via foramen magnum (pons compressed = cardiorespiratory arrest)
- rare

93

What is transtentorial herniation complication in meningitis?

- downward brain hernia
- brain expands inwards, towards pons/brain stem (motor / respiratory centre)
- can cause coma, death

94

What is infarct complication in meningitis?

- caused by vasculitis and vascular compression

95

How do you manage meningitis?

Supportive care
- specialist input
- if lacking, most common reason meningitis gets worse

Specific antimicrobial therapy
- give ASAP
- via IV (not all AB can cross BBB), IT (intrathecal - into spinal cord), IM, PO
- duration of treatment
- consider allergies / renal function

Steroids (?)
- views keep changing on use
- evidence shows in developed world - steroids beneficial if used before or with first dose AB.
- if given after 1st dose AB - effects unknown

Surgical intervention

Prophylaxis
- vaccinations - universal
- antibiotics - for ppl close to others with meningitis - prevents secondary infection

96

What is most common cause of meningitis getting worse?

Lack of supportive care / specialist input

97

What is early meningitis treatment?

ABCDE

98

What is late meningitis treatment?

Nutrition
Physiotherapy
Rehabilitation

99

What is issue with IV antibiotics?

Some drugs cannot cross BBB

100

What is alternative to IV is drug cannot cross BBB to treat meningitis?

Intrathecal injection (IT)

101

Which AB can cross BBB?

Penicillin
Ceftriaxone
Meropenem
Choramphenicol

102

Which AB cannot cross BBB?

Vancomycin
Gentamicin

103

What should your chose of AB depend on in treating meningitis?

- cause of meningitis
- route of administration

104

What other medication can be used with AB in meningitis treatment?

Steroids
- views keep changing on use
- evidence shows in developed world - steroids beneficial if used before or with first dose AB.
- if given after 1st dose AB - effects unknown

105

What types of supportive methods can be used with neurosurgery in meningitis?

- EVD - external ventricular drain (needed for hydocephalus)

- IT of AB (intrathecal injection of AB) - port needs to be added by surgeon

106

What surgery can be done in hydrocephalus?

EVD - external ventricular drain

107

What types of prophylaxis is available for meningitis?

- vaccinations - universal
- antibiotics - for ppl close to others with meningitis - prevents secondary infection

108

Who should you tell about pt with meningitis?

BACTERIAL meningitis is a notifiable disease
- public health issue
- legal requirement to tell public health authorities