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Micro 5 > export_cns bacteria i > Flashcards

export_cns bacteria i Flashcards

1
Q

Two main categories of CNS infections

A

Meningitis (affect meninges)

Encephalitis (affect brain parenchyma)

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2
Q

What makes up the blood brain barrier (BBB)?

A

Tight junctions between endothelial cells of cerebral microvasculature, epithelial cells of choroid plexus, and arachnoid cells

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3
Q

What does the BBB do?

A

Separates blood and CSF, isolating the CNS from the rest of the body

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4
Q

How do pathogens gain entry into the CNS?

A

Hematogenous spread from distant site of inoculation or infection (bacteremia)
Spread from adjacent/contiguous site to CNS

Direct inoculation

Neuronal spread

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5
Q

What is meningitis?

A

Inflammation of the meninges and CSF

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6
Q

What are the causes of meningitis, and which is the most severe?

A 
Acute pyogenic (bacterial) - most severe
Aseptic (viral)

Chronic (any class of microbe)

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7
Q

Increased risk for meningitis

A

Pneumonia or chronic otitis media (pneumococcal)

URTI (meningococcal)

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8
Q

Pathology of meningitis

A

Inflammatory mediators initiated due to toxins, resulting in edema, increased intracranial pressure, seizures, coma, and DEATH

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9
Q

Diagnose meningitis

A

Almost all patients have two of the following Sx:

Fever

Headache

Stiff neck

Altered mental status

Labs: CSF Gram-stain, cultures, latex agglutination

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10
Q

CSF abnormalities in bacterial meningitis

A

Presence of PMNs
Decreased glucose

Increased protein

Increased pressure

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11
Q

CSF abnormalities of viral meningitis/encephalitis

A

Monocytes and lymphocytes
Normal glucose

Normal/slightly increased protein pressure

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12
Q

Treatment of bacterial meningitis

A

Empirical antibiotic therapy

Using diagnostic tests can help determine most effective drug

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13
Q

Bacterial meningitis causative agents

A

S. pnuemo
N. meningitidis

S. agalactiae

Listeria monocytogenes

H. influenzae

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14
Q

S. pneumo features

A

Gram-positive cocci in chains
Catalase negative

Alpha-hemolytic

Susceptible to optochin and bile

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15
Q

What is the most common cause of vaccine-preventable death in the U.S.?

A

Pneumococcal meningitis

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16
Q

Pneumococcal virulence factors

A

Choline binding proteins
Pneumolysin

IgA protease

Capsule

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17
Q

Choline binding proteins

A

Allows for colonization in the oropharynx

18
Q

Pneumolysin

A

Inhibits mucociliary clearance

May also interfere with macrophage clearance

19
Q

Pneumococcal meningitis clinical importance

A

Acute onset
High mortality

Neurological sequela

20
Q

Pneumococcal meningitis recommended therapy

A

Vancomycin with a cephalosporin

Modify when organism is identified

21
Q

Pneumococcal polysaccharide vaccine (PPV)

A

Capsular polysaccharide Ag from 23 types of pneumococcus

Does not prevent pneumonia as effectively

22
Q

Who should get the PPV?

A

Adults > 65 years old

Anyone > 2 years old with increased risk

23
Q

Pneumococcal conjugate vaccine (PCV13)

A

Pneumococcal capsule (13 serotypes) conjugated to nontoxic diphtheria toxin

24
Q

Who should get the PCV13?

A

Routine child vaccine

2, 4, 6 months, then booster at 12-15 months

25
Q

N. meningitides features

A

Gram-negative diplococcus
Oxidase and catalase positive

Oxidizes BOTH glucose and maltose

Fastidious, requiring CO2

26
Q

N. meningitides virulence factors

A

Capsule

LOS

27
Q

N. meningitides transmission

A

~10% of population is colonized

Transmission is via aerosolized droplets

28
Q

Which serotypes cause almost all invasive meningococcal disease?

A

C
B

Y

W-135

A

29
Q

N. meningitides virulence factors

A

Pilli
Capsule

LOS

30
Q

LOS effects

A

Inflammation/immune response
Endotoxemia (organ failure)

DIC

31
Q

N. meningitides entry into CNS

A

BBB weakened

Cross BBB WITHIN neutrophils

32
Q

What is meningococcemia?

A

Bloodstream infection occurring with or without meningitis

33
Q

Meningococcemia Sx

A

Fever
Petechial/purpuric rash

Hypotension

Multiorgan failure

34
Q

What causes meningococcal meningitis?

A

Hematogenous dissemination

35
Q

Diagnose meningococcal meningitis

A

Gram-stain of CSF and/or blood
Bacteremia

Susceptibility testing

36
Q

Treatment for meningococcal meningitis

A

Again, start with vancomycin and a cephalosporin until identification has occurred
N. meningitides is usually susceptible to penicillin, so can use this after identification

37
Q

Meningococcal polysaccharide vaccine (MPV)

A

Tetravalent polysaccharide vaccine against serotypes A, C, Y, and W-135
Protection against B is on the way

38
Q

Who should get the MPV?

A

Not recommended as routine vaccination, but should be used in high-risk persons
In event of an outbreak

39
Q

What defines a meningococcal outbreak?

A

3+ cases in < 3 months

40
Q

Meningococcal conjugate vaccine (MCV4)

A

Tetravalent against A, C, Y, and W-135 (B still on the way)

Conjugated to nontoxic diphtheria toxin subunit

41
Q

Who should get the MCV4?

A

Anyone 11-55

9 months-55 years that have increased risk factors

42
Q

Differences between MPV and MCV4?

A

MCV4 illustrates a booster effect, and has a higher IgG response, and a higher affinity Ab response

Micro 5 (8 decks)

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