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Meningitis and encephalitis Flashcards

1
Q

What is the clinical presentation of bacterial meningitis?

A

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2
Q

What is the CSF profile of all the causes of meningitis?

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3
Q

What are the clinical differences btw. Viral and bacterial meningitis?

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4
Q

What are the most common organisms in viral meningitis?

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5
Q

How do you differentiate viral encephalitis and viral meningitis?

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6
Q

What is medical management protocol for bacterial meningitis? (age groups)

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7
Q

What is the epidemiology of bacterial meningitis?

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8
Q

What are the most common organisms for bacterial meningitis?

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9
Q

What’s the goal of bacterial meningitis treatment?

A

• This is a medical emergency so move fast
• Start appropriate empiric antibiotic therapy within 60 minutes of arrival to ER
○ ASAP

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10
Q

How many bacterial meningitis patients present with the classic symptoms?

A 
• There is the "classic triad" but only 45% of pts. Present with those
	• 100% present with 2/4:
		○ Headache
		○ Nuchal rigidity
		○ Altered mental status
		○ fever
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11
Q

Altered mental status in the context of bacterial meningitis means what?

A
  • Bad news. Severe or advanced case

* Also think encephalitis or brain abscess/empyema

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12
Q

What are the non-classic manifestations of bacterial meningitis?

A
  • Seizures
    • Nausea/vomiting
    • Myalgias
    • Cranial nerve palsies (III, VI, VII, VIII)
    • Focal deficits (hemiparesis, ataxia, gase preference)
    • Papilloedema in a small percent
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13
Q

What is the pathogenesis of bacterial meningitis?

A

• Disease of bacteria in the sub-arachnoid space
• Bacteria reach the sub-arachnoid space from :
• Bloodstream (most common)
• Adjacent intracranial infection (sinusitis, mastoiditis, otitis)
• Congential, traumatic or surgical defects in skull/spinal column
○ Endotoxin stimulates TNF and IL-1 release
○ BBB permeability increased
○ Neutrophil (PMN) recruitment which add to purulent exudate and enhance cytotoxic edema via ROS

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14
Q

The causative agents of bacterial meningitis will vary based on what conditions?

A
  • Patient’s age
    • Patient’s immune status
    • Community acquired vs. nosocomial infection
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15
Q

What organisms are important for the 23month to 34 year meningitis patient population (the largest most common age range)?

A
  • 40% neisseria meningitidis
    • 40% streptococcus pneumoniae
    • 10% Hemophilus influenzae
    • 5% streptococcus agalactiae (group B)
    • 1% Listeria monocytogenes
    • 1% staphylococcus species
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16
Q

What organisms are important for the 2-23 month meningitis patient population?

A
  • 50% streptococcus pneumoniae
    • 15% - Neisseria meningitides
    • 15% streptococcus agalactiae (group B strep)
    • 10% Haemophilus influenzae
    • 2% listeria monocytogenes
    • Small percent - staphylococcus species
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17
Q

What organisms are important for the under 2 months patient population?

A
  • Streptococcus agalactiae (group B strep)
    • Gram-Negative rods (enterobacteriaceae)
    • Listeria monocytogenes
    • Streptococcus pneumonia (pneumococcus)
    • Hemophilus influenzae
    • SMALL PERCENT (0-5%) Neisseria meningitidis (meningococcus)
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18
Q

What are the different age groups that you should group meningitis patients into?

A
  • Under 2 months
    • 2-23 months
    • 23 months - 34 years
    • Over 35 years
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19
Q

What do you need to do in the meantime if you are delaying LP for a CT/MRI?

A
  • Empiric antibiotic treatment STAT

* Blood cultures STAT and start empiric therapy

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20
Q

The protocol for dx of bacterial meningitis is lumbar puncture. When do you NOT do this?

A

• Though LP is the way to go before even neuroimaging, there are cases where LP is a bad idea right away

○ Reduced level of consciousness (low GCS score)
○ Focal neurologic defitics
○ Papilloedema
○ New onset seizures
○ History of CNS disease or an associated condition
§ Something that increases risk of brain abscess/empyema
○ Immunocompromised pt

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21
Q

What are the important organisms for the over 35 years group of meningitis patients?

A 
• 50-70% - streptococcus pneumoniae
	• 10-25% Neisseria meningitidis
	• 1-10% hemophilus influenzae
	• 10% listeria monocytogenes
		○ Though much more common in immune compromised or in pts over 60yrs
	• 10% gram-negative rods (nosocomial)
	• Less than 5% group B strep
		○ Which is less important apparently as you age
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22
Q

What are the domains of key data to be found in the CSF profile of a CNS infection?

A
  • WBC
    • Cell type
    • Glucose
    • Protein
    • Cultures
23
Q

What is the expected CSF profile for chronic meningitis (TB or fungi)?

A 
• WBC - 10-1K
	• Cell type - mononuclear
	• Glucose - low to normal
	• Protein - VERY elevated
	• Cultures - Tb, fungi, cryptococci
	•
24
Q

What is the expected CNS profile for viral meningitis?

A
  • WBC - 10-2K
    • Cell type - mononuclear (lymphocyte)
    • Glucose - normal
    • Protein - normal or slight elevation
    • Cultures - + /-(viral) - (bacterial)
25
Q

What is the expected CNS profile for bacterial meningitis?

A
  • WBC - 100-10K
    • Cell type - PMN (80-95%)
    • Glucose - Low (50mg/dL)
    • Cultures - + (bacteria)
26
Q

What is the expected CSF profile for encephalitis?

A
  • WBC - 10-2K
  • Cell type - mononuclear
  • Glucose - normal
  • Protein - elevated
  • Cultures - +/- viral or bacterial
27
Q

What is the expected CSF profile for brain abscess (LP not recommended)

A
  • WBC - less than 200
    • Cell type - mononuclear
    • Glucose - normal
    • Protein - normal or elevated
    • Cultures - + bacterial (unless ruptured)
28
Q

What are the useful stains or other tests for the different meningitis etiological agents?

A 
• Bacterial - gram stain
	• Viral - PCR
	• Chronic - AFB (acid-fast), India Ink (for the cryptobacilli)
		○ Crypto Ag (probably a ELISA)
		○ VDRL - The Venereal Disease Research Laboratorytest(VDRL) is a bloodtestfor syphilis that was developed by the eponymous lab. TheVDRL testis used to screen for syphilis (it has high sensitivity), whereas other, more specifictestsare used to diagnose the disease.
		○ TB PCR
	• Encephalitis - PCR, MRI
	• Abscess - MRI/CT (head and sinuses)
29
Q

What is true about the specificity and sensitivity of the gram stain?

A 
• It changes depending on the lab, and certainly depending on the organism
	• Sensitivity (true positive) - 60-90%
	• Specificity (descending order)
		○ H flu and pneumococcus - 90%
		○ Meningococcus
		○ Gram negative rods
		○ Listeria - 33%
30
Q

In what percentage of bacterial meningitis patients are bacterial CSF cultures positive?

A
  • 70-85% (unless there was treatment before LP)

* Blood cultures are more like 30-50% positive

31
Q

Assuming the patient is immunocompetent and they have community acquired disease, what are the empiric treatment choices for: Children and adults?

A 
• 3 months to 50 yrs
		○ Ceftriaxone OR
		○ Cefotaxime AND vancomycin
	• Over 50 years
		○ Ceftriaxone OR
		○ Cefotaxime AND vancoycin AND ampicillin
32
Q

What is the MRI used for in the meningitis case?

A

• Can show meningeal enhancement because of inflammation
• More used for searching out complications
○ Cerebral edema, ventriculitis, hydrocephalus, infarction, parameningeal or intracranial focal suppuration

33
Q

Assuming the patient is immunocompetent and they have community acquired disease, what are the empiric treatment choices for: Neonates and infants?

A

• Less than 3 months

○ Ampicillin AND cefotaxime

34
Q

What is the empirical meningitis treatment in nosocomial infections, recent head truama/sugery, immunocompromised and alcoholics?

A

• Any age!
○ Vancomycin AND meropenem
○ +/- additional ampicillin (for listeria)

35
Q

Vancomycin is used in nosocomial meningitis infections (and community acquired for that matter) why?

A
  • Covers penicillin/cephalosporin resistant pneumococci and coagulase-negative and MRSA staph
    • Also covers enterococcus species
36
Q

Meropenem is used for nosocomial meningitis infections why?

A
  • Covers pseudomonas and other resistant gram-negative rods

* Cefepime is a common alternative

37
Q

What tests should CSF pneumococci undergo?

A
  • Though resistance is still fairly rare:
    • Test for MICs to penicillin.
    • IF AT ALL penicillin resistent then test MICs of cephalosporins (3rd generation)
    • IF AT ALL RESISTANT to either or both then repeat LP after 24-36 hours to confirm and document sterilization of CSF culture
38
Q

How long is the treatment course for bacterial meningitis?

A
  • 7 days for meningococcus and H flu
    • 10-14 days for pneumococcus
    • 21 days for gram negative species (including neisseria meningiditis)
    • 21+ days for listeria
39
Q

If somebody is worried about a culture being ruined by empirical treatment for bacterial meningitis, what should you remember?

A

within 4 hours, there is little to no effect either on gram stain or culture results of LP

40
Q

When would you use steroids in meningitis treatment?

A
  • Steroids can be helpful in strep pneumoniae cases ONLY
    • Discontinue if you find another organism
    • Admin 10-20 min before 1st antibiotic dose or concurrent with first dose
    • NO ROLE after antibiotics have started
41
Q

What are the common viral causes of meningitis?

A

• Enteroviruses
• HSV-2
• Arboviruses
○ West nile virus (WNV)

42
Q

What are the viruses that RARELY cause meningitis?

A
  • Adenoviruses
    • CMV
    • Influenza A and B
    • LCMV
    • MMR
    • Parainfluenza and rotavirus
43
Q

What are the less common (intermediate) viral causes of meningitis?

A
  • HSV-1
    • EBV
    • VZV
    • HIV
    • HHV-6
44
Q

What is dx protocol for viral meningitis?

A

• CSF sample (LP)
• Lymphocytic pleocytosis with normal glucose
○ Exceptions are WNV (PMNs) and low glucose in mumpts, LCMV and HSV2
• PCR amplification of viral genomic material is most specific and important dx test

45
Q

What antiviral therapies are available for viral meningitis treatment?

A
  • Acyclovir - HSV, VZV
    • Antiretrovirals - HIV
    • Foscarnet, ganciclovir, cidofovir - CMV
    • Rimantidine - flu
    • Pleconaril - enteroviruses
    • Supportive treatment - WNV
46
Q

What’s the difference between viral encephalitis and viral meningitis?

A

• Infection in the brain parenchyma, as opposed to infection in meninges

47
Q

What are the clinical manifestations of viral encephalitis?

A
  • Altered consciousness, fever, headage
    • Seizures and focal neurological signs
    • Personality change
    • Alteration in mental status
    • Alteration in level of consciousness
    • Aphasia
    • Hemiparesis
    • Ataxia
    • Cranial nerve palsies
    • Visual field loss
    • Tremors
    • Myoclonus
    • Parkinsonism (WNV)
48
Q

What is the seasonality to viral encephalitis?

A 
• Seasonality in the etiological agent
	• Summer/early fall
		○ Arboviruses (WNV) - most important cause US
		○ Enteroviruses
		○ Zika virus (fetal)
	• Fall and winter
		○ LCMV - lymphocytic choriomeningitis virus
	• Winter and spring
		○ Mumps
	• Any season
		○ HSV - most important cause US
		○ EBV
		○ CMV
49
Q

What are the most important causative agents of viral encephalitis in the USA?

A

HSV and WNV

50
Q

Where is west nile virus endemic in the USA?

A

• Western and midwest states

51
Q

What is the diagnostic protocol of viral encephalitis?

A

• CSF pleocytosis
• EEG abnormal (up to 90% of patients)
• CT and MRI are helpful in ID of focal encephalitis and r/o other mimics of disease
• PCR amplification of viral nucleic acid from CSF is gold standard
○ HSV, VZV, CMV, EBV, enteroviruses
• WNV IgM detection in CSF is dx of WNV (better than PCR)

52
Q

What is the therapy regimen for viral encephalitis?

A 
• Treatment is mostly for herpes viruses
		○ Adult HSV
		○ Neonatal HSV
		○ VZV
	• All acyclovir
*empiric therapy is acyclovir
53
Q

What are the clinical features of Bacterial meningitis?

A

• Classic triad (only 45% patients have the classic triad though)
○ Fever, headache and neck stiffness (nuchal rigidity/meningismus)
• 100% of patients have at least 2 of the 4 symptoms
○ Fever, Headache, nuchal rigidity, altered mental status

Neuro (59 decks)

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