Week 3- CNS infections Flashcards Preview

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Flashcards in Week 3- CNS infections Deck (57)
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1
Q

What can untreated infection in the brain lead too?

A

Brain herniation and death.

Cord compression and necrosis with subsequent paralysis.

2
Q

Which organisms can cause community acquired bacterial meningitis?

A

Pneumonoccus
Menigicoccus
H- influenza.
Listeria spp (over 60’s or immunocompromised)

3
Q

What is the treatment for community acquired bacterial meningitis?

A

Ceftriaxone IV plus dexamethasone IV.

4
Q

1) Treatment for community acquired meningitis if its listeria ?
2) If its listeria and penicillin allergic?

A

Amoxicillin IV plus normal community acquired treatment (ceftriaxone IV plus dexamethasone IV)
Chloramphenical IV plus dexamethasone

5
Q

When would you stop dexamethasone in a community acquired meningitis?

A
If you find out the causative organism is-
meningococcus
Listeria (common in 60+ years)
H influenza
Other gram neg
6
Q

What treatment would you add if you found out the causative organism for a community acquired meningitis is Listeria?

A

Add amoxicillin.

7
Q

Which pathogen commonly causes viral meningitis?

A

Enterovirus e.g. ECHO

8
Q

How would you diagnose a viral meningitis?

A

Stool culture
CSF PCR
Throat swab

9
Q

Treatment of a viral meningitis?

A

Generally supportive because its self limiting.

10
Q

Clinical features of encephalitis?

A

Insidious (gradual) onset
Meningismus (triad of headache, photophobia and nuchal rigidity (impaired neck flexion))
Stupor (state of near unconsciousness), coma
Siezures, partial paralysis
Confusion, psychosis
Speech, memory symptoms

11
Q

Investigations into encephalitis? What are they likely to show?

A

Bloods- blood cultures, serum for viral PCR
Lumbar puncture- likely to show increased CSF protein and lymphocytes and decreased glucose.
EEG (electrocephalogram- test detecting brain activity)- diffuse abnormalities.
Contrast enhanced CT- will show focal bilateral temporal lobe involvement. MRI if allergic to contrast.

12
Q

When should you start treatment for encephalitis?

A

If delay in tests, start pre-emptive aciclovir due to it drastically improving outcomes when started early.

13
Q

Symptoms of meningitis (and septicaemia- blood poisoning)

A

Early symptoms

  • headache
  • leg pain
  • neck stiffness
  • cold hands and feet
Later symptoms
-reduced conscious level and confusion
-Meningism- sore neck, photophobia and Kernigs sign (pain and resistance on passive knee extension with hip fully flexed)
Non blanching petechial rash ever
Possibly seizures
14
Q

Which bacterial meningitis (community acquired) are neonates likely to get?

A

Listeria (occurs in extremes of age)
Group B streptococci
E.coli

15
Q

Which bacterial meningitis (community acquired) are children likely to get?

A

H influenza

16
Q

Which bacterial meningitis (community acquired) are age 10-21 likely to get?

A

Neisseria Meningitidis

17
Q

Which bacterial meningitis (community acquired) are age over 21’s likely to get?

A
Strep pneumoniae (most likely)
Neisseria meningitidis
18
Q

Which bacterial meningitis (community acquired) are age over 65s likely to get?

A
Strep pneumoniae (most likely)
Listeria.
19
Q

Which bacterial meningitis (community acquired) are immunocompromised patients likely to get?

A

Listeria

20
Q

Which bacterial meningitis (community acquired) are patients who have recently had neurosurgery likely to get?

A

Staphylococcus

Gram neg bacilli

21
Q

Which bacterial meningitis (community acquired) are patients who have fractured their cribriform plate likely to get?

A

Strep pneumoniae.

22
Q

Meningitis can leave you with life altering after affects, what can these be?

A

Limb loss, deafness, blindness, cerebral palsy, quadriplegia, severe mental impairment.

23
Q

Complications of meningitis

A

Purulence (pus)- can compress cranial nerves (esp III and IV). Can cluster at the base of the brain.
Abscesses- if it invades the Pia mater.
Cerebral oedema
Ventriculitis/hydrocephalus

24
Q

Describe the pathogenesis of bacterial meningitis?

A

The nasopharynx becomes colonised. Direct extension of bacteria (through fractures in the skull or parameningeal foci (sinusitis, mastoiditis, brain abscess).

25
Q

Which pathogen causes mengiococcal meningitis?

A

N. Meningitidis

26
Q

Pathogenesis of N meningitidis?

A

Found in the throats of healthy carriers. Bacteria probably gain access to the meninges via the bloodstream. The bacteria may also be found in leukocytes in the CSF.

27
Q

What causes N meningitidis to have symptoms?

A

The endotoxin released.

28
Q

H influenza is part of the normal throat microbiota? True or false

A

True- it requires blood factors for growth and to become pathogenic.

29
Q

Which type of H influenza most commonly affects children under 4?

A

Type b.

30
Q

Who is most susceptible to S pneumoniae meningitis?

A

Hospitalised patients, patients with CSF skull fractures, diabetics/alcoholics and young children.

31
Q

What might S pneumoniae be linked too?

A

CNS devices e.g. cochlear implant. Rare but high mortality rate.

32
Q

Which drug has no value against listeria monocytes

A

Ceftriaxome- they are intrinsically resistant. Use IV ampicillin or amoxicillin.

33
Q

Who is likely to get tuberculosis meningitis?

A

Reactivation in the elderly

34
Q

What signs is someone with tuberculosis meningitis likely to show?

A

Need a very high level of suspicion to diagnose. Previous TB infection with poor yield on CSF, fairly non-specific ill health.

35
Q

Treatment of tuberculosis meningitis?

A

Rifampicin plus isoniazid

You can add pyrazinamide and ethambutol

36
Q

What fungal infection can cause meningitis?

A

Cryptococcal (crytococcal meningitis)

37
Q

Signs to point you towards a diagnosis of cryptococcal meningitis?

A
HIV disease
Subtle neurological signs
Aseptic CSF
CD4<100
Disseminated infection
38
Q

Treatment of cryptococcal meningitis?

A

IV Amphotericin B/ Flucytosine Fluconazole

39
Q

When should lumbar puncture be delayed in suspected bacterial meningitis?

A
Signs of severe sepsis or rapidly evolving rash. 
Respiratory or cardiac compromise
Anticoagulant therapy/known thrombocytopenia
Infection at the site of LP
Focal neurological signs
Presence of papilloedema 
Continuous or uncontrolled seizures
GCS<12
40
Q

Principles of lumbar puncture in meningitis?

A

If flow fast- measure pressure
Be cautious if there is increased ICP
Be careful with delirium
TREAT WITH ANTIBIOTICS FIRST.

41
Q

What things are you looking for in a lumbar puncture?

A

Haematology- WCC, RBC, differential
Microbiology- gram stain, cultures
Chemistry- glucose, protein

42
Q

NOTE

A

Bacterial meningitis can be culture negative on LP

Could be due to already treating with antibiotics.

43
Q

Typical CSF findings in a viral meningitis

A
Lymphocytes 10^1-10^3
Gram stain- negative
Bacterial antigen detection- negative
Glucose- normal (2.3-4.5)
Protein-normal (0.1-0.4)
44
Q

Typical CSF findings in bacterial meningitis

A
Lymphocytes 10^1-10^4 (predominantly polymorphs e.g. neutrophils) 
Gram stain- positive 
Bacterial antigen detection- positive
Protein- high
Glucose-less than 70% of blood glucose.
45
Q

Typical CSF findings in tuberculosis meningitis

A
Lymphocytes- 10^1-10^3- predominantly lymphocytes
Gram stain- positive or negative
Bacterial antigen detection-negative
Protein- high or very high
Glucose-less than 60% of blood glucose
46
Q

When is the CSF 99% predictive of bacterial meningitis?

A

When the WCC >2000, Neutrophils >1180, Protein >220

Glucose< 34 and glucose CSF/serum <0.23

47
Q

What else can cause low CSF glucose and high neutrophils (apart from bacterial meningitis)?

A
Early phase viral meningitis
Some parameningeal foci
Leakage of brain abscess into ventricle
Amebic meningoencephalitis
Drug induced (NSAIDS)
Chemical meningitis
Behcet syndrome
48
Q

What is aseptic meningitis?

A

Non-pyogenic (non-pus producing) bacterial meningitis

49
Q

What will the spinal fluid of aseptic meningitis be like?

A

Low number of WBC
Minimally elevated protein
Normal glucose

50
Q

What infections can cause aseptic meningitis?

A
HSV 1 and 2
Syphilis 
Listeria (occasionally)
TB
Cryptococcus
Leptospirosis
Cerebral malaria
African tick typhus
Lyme disease
(ALL TREATABLE)
51
Q

What non-infectious agents can cause aseptic meningitis?

A
Carcinomatous
Sarcoidosis
Vasculitis
Dural venous sinus thrombosis
Migraine
Drug- co-trimoxazole, IVIG, NSAIDs
52
Q

Indications for hospital admission in adult bacterial meningitis?

A
Signs of meningeal irritation
Reduced conscious level
A petechial rash
Febrile, unwell or recent fit
Any illness, esp headache.
53
Q

On arrival in hospital, the doctor should do the following to deal with bacterial meningitis

A

Blood culture and coag screen
Give treatment as outlined.
Throat swab
Aspirate and swab any petechial or purpuric skin lesions

54
Q

Who should undergo a CT prior to lumbar puncture?

A
Immunocompromised patients
History of CNS disease
New onset siezure
Papilloedema
Abnormal level of consciousness
Focal neurological deficit
55
Q

When should you give steroids to patients with bacterial meningitis?

A

Should give to all patients with suspected bacterial meningitis with the antibiotics.

56
Q

When should you not give steroids to patients with bacterial meningitis?

A

Do not give in post-surgical meningitis, severe immunocompromised, meningococcal or septic shock or those that are hypersensitive to steroids.

57
Q

When should you report meningitis to public health?

A

ASAP- to minimise secondary infections.