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Neuro Block 2 - KJ > Intro to CNS Infections > Flashcards

Intro to CNS Infections Flashcards

1
Q

What does prednisone do and what does it treat?

A

Rheumatoid arthritis

-It can make a patient more immunocompromised

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2
Q

What are the ‘Big three’ CNS infection symptoms?

A

Fever, headache, altered mental state

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3
Q

What are infectious causes of CNS infection?

A

Meningitis, Encephalitis, Abscess

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4
Q

What are non-infectious causes of CNS infections?

A

-Subarachnoid hemorrhage, inflammatory disease-lupus, Neoplasia, Metabolic, Drug (NSAIDs)

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5
Q

What is the most common cause of bacterial meningitis?

A

Neisseria meningitis

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6
Q

What is the most common cause of encephalitis?

A

Viral/Herpes viral

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7
Q

What is the most common cause of abscess?

A

Strep, Staph

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8
Q

What is the most common cause of encephalopathy?

A

Build up of ammonia

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9
Q

Where does meningitis occur?

A

Subarachnoid Space

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10
Q

Where does encephalitis occur?

A

Diffuse parenchyma

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11
Q

Where does abscess occur?

A

Focal parenchyma

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12
Q

Where does myelitis occur?

A

Spinal cord

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13
Q

Tell me about Meningitis:

A
  • 95% will have 2 of: headache, fever, nuchal rigidity and altered mentality
  • Viral (most common)
  • Bacteria (life-threatening)
  • Fungi, protozoa (immunocompromised)
  • Pathogens affect different ages
  • Virulence factors like capsules allow pathogen to evade immune system
  • Vaccines available against several strains of life-threatening bacteria
  • Stiff neck = cue you in to meningitis
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14
Q

What is encephalitis?

A

Diffuse infection of parenchyma.

  • Fever, headache, and alterations of mental status
  • Motor and sensory deficits not seen in meningitis
  • Progression to seizures, speech disturbances, lethargy and coma
  • 33-66% of cases etiology is unknown despite an extensive diagnostic workup
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15
Q

What is the cause of most non-viral encephalitis?

A

Rickettsia, Mycoplasma, Acute disseminated encephalomyelitis (ADEM)

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16
Q

What is the cause of most viral encephalitis?

A

Enterovirus, Arbovirus, Herpes virus, Rabies

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17
Q

What is a brain abscess and what are its symptoms?

A

Focal infection of parenchyma.

  • Symptoms: fever, headache, neurological defects, seizure
  • Pre-existing ischemia, necrosis begins as cerebritis and then becomes encapsulated
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18
Q

What causes brain abscesses?

A

Mixture of bacteria: Streptococci (most common), Pseudomonas, Haemophilus, Staphylococcus, Bacteroides
[Mycobacterium, Fungi, Parasites - in immunocompromised]

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19
Q

What can happen to brain abscesses that rupture?

A

-They can cause meningitis or damage in other areas
-Otitis media > temporal lobe/cerebellum
-Dental/sinus infection > frontal lobe
-Hematogenous > multiple
Territory of middle cerebral artery
Trauma

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20
Q

What shows up in encephalitis?

A

Inflammation of brain

  • Fever, headache, focal neurologic signs, seizures (generalized or focal), mental status may fluctuate
  • Leukocytosis common in CBC, Pleocytosis common in CSF, diffuse slowing and occasional focal abnormalities or periodic patterns in electroncephalogram, may have focal abnormalities in MRI
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21
Q

What shows up in encephalopathy?

A

Abnormal brain function/structure

  • Refers to diffuse cerebral dysfunction without inflammation usually due to toxin or metabolic dysfunction
  • Steady decline in mental status, Seizures are uncommon but generalized
  • Not many symptoms (symptoms are uncommon)
  • No focal abnormalities on MRI
  • Diffuse slowing seen in electroencephalogram
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22
Q

Why are infections of CNS uncommon?

A
  • Scalp & skull helps protect from external entry
  • 3 meninges (dura, arachnoid, pia) surround brain and spinal cord
  • Epidural abscess limited due to tight attachment of dura to periosteum
  • Tight junctions of blood-brain barrier prevent organisms from entering CNS
  • Vaccination
23
Q

What is the role of microglia and astrocytes in innate immune cells in CNS?

A

Secrete cytokines and cheekiness that help recruit in macrophages and T cells

24
Q

What is the role of macrophages and T cells in innate immune response of CNS?

A

-Clear pathogens and repair tissue damage

25
Q

How can patients transmit infections of the brain?

A
  • Placental-fetal, milk
  • Respiratory
  • Sexual
  • Oral
  • Zoonotic (ex: Lyme’s disease)
  • Blood transfusion
  • Trauma
26
Q

How do the microbes invade the brain??

A
  • Hematogenous dissemination (blood)
  • Contiguous spread from sinusitis, otitis media, mastoiditis
  • Trauma or congenital lesions
  • Retrograde axonal transport (this happens wiht rabies to get the organism back up in the brain)
27
Q

When does Enterovirus usually occur?

A

In later summer to fall

28
Q

What is the most common cause of viral meningitis and encephalitis?

A

Enterovirus

29
Q

What can geography tell you about a meningitis or encephalitis?

A

-May cue you in on whether it is cause by Tick exposure (lyme), West Nile Virus

30
Q

What caused the woman’s encephalitis?

A

Listeria monocytogenes

-Mortality rate = 25%!

31
Q

What are the steps you should take if you suspect bacterial meningitis?

A
  1. History & Physical
  2. Blood culture & Start immediate antibiotic treatment
  3. Neuroimaging
  4. Lumbar puncture/biopsy
  5. Identify organism (Gram stain/PCR/RT-PCR)
  6. Switch to definitive treatment based on antibiotic susceptibility tests and/or supportive therapy
32
Q

What antibiotic should be given first for CNS infection (if you need to aggressively manage)?

A
  • Empiric antibiotic - 3rd generation cephalosporin [beta-lactam] & additional agents if certain etiologies are suspected
  • Dexamethasone (when you kill of the bacteria you will get a lot of inflammation/leakiness of brain) decreases inflammation in subarachnoid space
33
Q

What are the benefits of 3rd generation cephalosporin/agressive antibiotic to first manage CNS infection?

A
  • Bactericidal - 10 fold greater than minimum inhibitory concentration
  • Small, lipophilic, low affinity for plasma binding proteins, and not a ligand of the efflux pumps at the blood brain barrier
34
Q

What else should be done to aggressively manage CNS infection?

A

Consider prophylactic treatment of close contacts (not necessary for Listeria, but is necessary for air-spread organisms)
-Antibiotic susceptibility testing for drug resistance

35
Q

The primary mechanism of antibacterial action of Ceftriaxone involves inhibition of. . .

A

. . .transpeptidation of peptidoglycan

36
Q

What empiric 3rd generation cephalosporin was chosen for the case study?

A

Ceftriaxone + Ampicillin (if Listeria)

37
Q

What is the mechanism of Ceftriaxone? What drug class is it?

A

3rd generation cephalosporin

Binds to penicillin binding proteins (transpeptidases) to inhibit cell-wall synthesis

38
Q

What resistance has developed against 3rd gen cephalosporins? What are the side effects?

A

Inactivaiton of the drug by beta-lactamases.

Allergies

39
Q

What is the spectrum of 3rd generation cephalosporin?

A

Used for streptococci and more serious Gram - infections, can cross blood-brain barrier

40
Q

What are three good CNS drugs?

A
  • Aminoglycosides
  • Beta-lactams
  • Macrolides, azalides
41
Q

What side effects do aminoglycosides cause?

A

Ototoxicity, peripheral neuropathy, encephalopathy (gentamicin), neuromuscular blockade

42
Q

What side effects do Beta-lactams cause?

A

Encephalopathy with triphasic waves on EEG, Tardive seizures, seizures, NCSE, Myoclonus, Asterexis, Watch for Renal Failure!

43
Q

What side effects do macrocodes, azalides cause?

A

Ototoxicity, damage to cochlea

44
Q

What does neuroimaging show in regards to meningitis?

A

Head CT normal but MRI shows leptomeningeal enhancements but no focal lesions

45
Q

What should not be done if there is a focal mass lesion?

A

Lumbar puncture, due to risk of brain herniation

46
Q

What are the routine screenings done with a lumbar puncture?

A
  • WBC count with differential
  • RBC count
  • Glucose concentration
  • Protein concentration
  • Gram stain
  • Bacterial culture
47
Q

What is a lumbar puncture done for?

A

To collect CSF in patients with suspected CNS infection (between 3rd and 4th lumbar vertebrae)

48
Q

What doe the lumbar puncture look for a patient with Listeria?

A
  • Elevated protein, dec. glucose, in. PMNs
  • Intracellular, gram + rod
  • Pos. CSF culture in 40% Listeria cases
  • Pos. blood culture in 60% of Listeria cases
  • Serology & culture of stool is unreliable
49
Q

What are CSF findings in patients with meningitis?

A

-High WBCs, High pressure, high protein, low glucose indicate meningitis

50
Q

What does glucose level go down in CSF of meningitis?

A

Bacteria are eating your glucose!

51
Q

What are the properties of Listeria monocytogenes?

A

Gram +, rod

  • Intracellular pathogen, in environment
  • Fever, headache, nuchal rigidity (diarrhead)
  • Immunosuppressed (pregnancy), old, newborns
  • Consumption of contaminated food - unpasteurized milk, cheese and deli meats
52
Q

How does Listeria monocytogenes cause infection?

A
  • Internalin induces phagocytosis by epithelial cells of the GI track, and phospholipase and listeriolysin O allow escape from vacuole
  • Actin tails facilitate pseudopod spread between adjacent cells
53
Q

What is a more definitive therapy for Listeria monocytogenes?

A

Ampicillin + Gentamicin

Neuro Block 2 - KJ (14 decks)

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