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Question Bank > CNS Infections > Flashcards

CNS Infections Flashcards

1
Q

Patient with fever, headache, neck stiffness, photophobia.

Brudzinski and Kernig negative

How useful is this information?

A

Does not exclude bacterial meningitis.

Fever/ headache/ photophobia/ neck stiffness more sensitive

Kernig - bend knee, extend leg, worse pain in neck

Brudzinski - supine patient, lift head off bed - legs will flex off bed

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2
Q

Patient with fever, headache, neck stiffness, photophobia.

Do they need CT before LP?

A

Only CT if -

GCS 12 or less
seizures
focal neurological deficit
severely immunocompromised

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3
Q

Patient with fever, headache, neck stiffness, photophobia.

Started on antibiotics and steroids

CSF
WCC 450
Protein 1500
Glucose 1

Microscopy shows gram positive diplococci

What is pathogen?

A

Strep pneumoniae

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4
Q

60 year old patient with fever, headache, neck stiffness, photophobia.

Started on antibiotics and steroids

CSF
WCC 450
Protein 1500
Glucose 1

Which antibiotics should be used?

A

Ceftriaxone + amoxicillin

to cover for listeria in age group

If identify strep pneumoniae as cause, can step down to benzylpenicillin

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5
Q

What is role of corticosteroids in meningitis?

A
  • Strep pneumoniae - small reduction in mortality

- Haemophilus - less severe hearing loss in children

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6
Q

Patient with fever, headache, neck stiffness, photophobia.

Started on antibiotics and steroids

CSF
WCC 450
Protein 1500
Glucose 1

Microscopy shows gram positive diplococci - pneumococci

Should pneumococcal isolate be sent for serotyping?

A

Yes

helps identify pattern of strains, and whether they are covered by routine vaccination schedule

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7
Q

Patient with fever, headache, neck stiffness, photophobia.

Started on antibiotics and steroids

Microscopy shows gram positive diplococci - pneumococci

Should patient be vaccinated to prevent further episodes of invasive pneumococcal disease?

A

Yes - if not vaccinated in past 5 years

Patients >65, and those with chronic disease, will be routinely vaccinated

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8
Q

What are treatment options for strep pneumoniae?

Penicillin susceptible

Penicillin resistant

Cephalosporin resistant

A

Penicillin susceptible - benzylpenicillin

Penicillin resistant - ceftriaxone

Cephalosporin resistant - vancomycin + rifampicin

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9
Q

What is duration of treatment of each infection?

Strep pneumoniae

Neisseria meningitidis

Haemophilus

Listeria

A

Strep pneumoniae - 14 days

Neisseria meningitidis - 7 days

Haemophilus - 10 days

Listeria - 21 days

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10
Q

45 year old, 5 day history of fever, fatigue. Last 24 hour erratic behavior, and had a seizure.

Temp 38degC
GCS 13

What is differential diagnosis?

A

encephalitis - HSV causes 50% of cases

SOL

vascular event

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11
Q

45 year old, 5 day history of fever, fatigue. Last 24 hour erratic behavior, and had a seizure.

Temp 38degC
GCS 13

Patient is immunocompromised.

What rarer differential diagnoses need to be considered?

A

HHV6

CMV

EBV

Acanthomoeba -

  • Balamuthia mandrillaris 90% mortality
  • Naeglaeri Fowleri

Syphilis

Cryptococcus

TB

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12
Q

Patient with AML, presents with fever, headache, seizure. CT shows possible abscess

What is empirical treatment?

A

Ceftriaxone and metronidazole

consider anti-fungal such as ambisome or voriconazole as immunosuppressed

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13
Q

Patient with AML, presents with fever, headache, seizure. CT shows possible abscess

Patient keeps ornamental fish at home, lives in countryside.

Recently treated for otitis media by GP

What are possible causes of abscess?

A

Nocardia - filamentous gram positive species, part of normal human flora.

Also found in soil/ water - so pond may explain cause

Can occur in immunocompetent, but most occur in immunocompromised

First line treatment is co-trimoxazole for 6-12 months

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14
Q

18 year old presents with headache, vomiting, and eventually reduced GCS.

Brain imaging shows mass in pineal gland, with associated haemorrhage and hydrocephalus

Neurosurgery evacuate of blood, and insert extra-ventricular drain (EVD)

3 days later he develops fever

What are possible sources?

A

Chest - was intubated
Urine - catheter
Lines
EVD

Can be normal body response to bleeding/ surgery. If fever associated with tachycardia/ hypotension, more likely to be caused by infection

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15
Q

18 year old presents with headache, vomiting, and eventually reduced GCS.

Brain imaging shows mass in pineal gland, with associated haemorrhage and hydrocephalus

Neurosurgery evacuate of blood, and insert extra-ventricular drain (EVD)

3 days later he develops fever

CSF from EVD
WCC 320 polymorphs 200 lymphocytes 120
RCC 6400
No organisms gram stain
Glucose 6.4
Protein 0.6

Should antibiotics be started before culture results are available?

A

Decision complicated by elevated protein/ RCC/ WCC from recent neurosurgical procedure

If patient unstable - treat for meningitis, until alternative diagnosis found.

This may include repeat CSF sampling at 48 hours

Most common cause is staph aureus, including coagulase negative staph.

Consider IV antibiotics such as ceftriaxone, and intrathecal antibiotics such as vancomycin

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16
Q

18 year old presents with headache, vomiting, and eventually reduced GCS.

Brain imaging shows mass in pineal gland, with associated haemorrhage and hydrocephalus

Neurosurgery evacuate of blood, and insert extra-ventricular drain (EVD)

3 days later he develops fever

CSF from EVD
WCC 320 polymorphs 200 lymphocytes 120
RCC 6400
No organisms gram stain
Glucose 6.4
Protein 0.6

culture grows coagulase negative staph

What are next steps?

A

If no other source, consider it pathogenic.

Repeat cultures to confirm this

remove EVD, as poor response with antibiotics alone. Replace EVD at different site if still required for intracranial pressure management

usually give antibiotics from 7 days after last negative culture

17
Q

18 year old presents with headache, vomiting, and eventually reduced GCS.

Brain imaging shows mass in pineal gland, with associated haemorrhage and hydrocephalus

Neurosurgery evacuate of blood, and insert extra-ventricular drain (EVD)

Treated for EVD infection.

Biopsy of pineal gland shows germinoma. Starts chemotherapy. Five days late becomes GCS 8, and unwell. Yeasts seen on CSF

Candida parapsilosis found on culture

What are next management steps?

A

liposomal amphotericin B
Once improved, switch to oral fluconazole

removal of device - either re-insert EVD, or use temporary lumbar drain. Only re-insert once culture is negative after treatment

18
Q

Advanced HIV, not on treatment. Progressive confusion.

MRI shows diffuse white matter changes, with lesions.

What are differentials?

A

PML - JC virus

toxoplasmosis

lymphoma

19
Q

How to diagnose PML?

A

MRI

brain biopsy - rarely done

CSF - JC virus PCR

20
Q

Advanced HIV, not on treatment. Progressive confusion.

MRI shows diffuse white matter changes, with lesions, thought to be PML.

Patient subsequently started on ART. Initial improvement, then deteriorates. MRI shows areas of oedema around noted previous demyelination

What is explanation for this?

A

immune reconstitution syndrome (IRIS) - can be associated with JC virus

CD4 cells recover, and immune system stimulated

can lead to headache, neurological deficits, seizures

ART is treatment for JC virus

also see JC virus infection in immunocompromised e.g haematological conditions, patients on monoclonal antibodies e.g natalizumab

21
Q

What treatment is available for IRIS due to JC virus infection?

A

corticosteroids

22
Q

TB meningitis

Which drugs cross BBB freely?

A

Isoniazid

Pyrazinamide - to lesser extent

23
Q

Patient with meningitis bacterial.

Why is glucose usually low?

A

Neutrophils use glucose for energy, for phagocytosis.

Bacteria very minimally “use it up”

24
Q

Why is alcohol abuse/ liver cirrhosis strongly associated with S.pneumoniae meningitis?

A

Alcohol suppresses cough reflex - allowing bacteria into alveolar spaces

Alcohol reduces ciliary clearance

Alcohol reduces neutrophil recruitment

25
Q

Why does Cryptococcus stain gram variable in CSF?

A

Capsule may stain gram neg, while yeast cell stains gram pos

Use India ink stain

26
Q

CrAg does not distinguish between Cryptococcal neoformans, and Cryptococcal gattii

What are differences in clinical picture?

A

Cryptococcal gattii -

  • more likely to infect immunocompetent, but still infects immunocompromised
  • more likely cause pulmonary disease
27
Q

Patient comes in unwell, with apparent sepsis.
Give broad spectrum antimicrobials.

Patient deteriorates further. Thought to have botulism

Which antimicrobial class contra-indicated in boutlism infection?

A

Aminoglycosides may exacerbate the symptoms of botulism by competitive inhibition of the presynaptic portion of the neuromuscular junction and by decreasing acetylcholine release from nerve terminals.

Therefore in patients with ptosis/ hypotonia and unwell, use of aminoglycosides should be avoided until the diagnosis of botulism can be ruled out

28
Q

Patient with PML

What are possible treatment options?

A

Stop immunosuppression/ start ARVs - although can cause IRIS, which may need steroid treatment

Mirtazipine shows some benefit

Cidofovir/ mefloquine/ cytarabine all been used with minimal benefit

Question Bank (33 decks)

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