export_cns bacteria i

Question 1

Two main categories of CNS infections

Answer 1

Meningitis (affect meninges)

Encephalitis (affect brain parenchyma)

Question 2

What makes up the blood brain barrier (BBB)?

Answer 2

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

Question 3

What does the BBB do?

Answer 3

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

Question 4

How do pathogens gain entry into the CNS?

Answer 4

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

Direct inoculation

Neuronal spread

Question 5

What is meningitis?

Answer 5

Inflammation of the meninges and CSF

Question 6

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

Answer 6

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

Chronic (any class of microbe)

Question 7

Increased risk for meningitis

Answer 7

Pneumonia or chronic otitis media (pneumococcal)

URTI (meningococcal)

Question 8

Virulence factors for meningitis

Answer 8

Capsule
Fimbriae

Pili

MOMPs

Question 9

Pathology of meningitis

Answer 9

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

Question 10

Diagnose meningitis

Answer 10

Almost all patients have two of the following Sx:

Fever

Headache

Stiff neck

Altered mental status

Labs: CSF Gram-stain, cultures, latex agglutination

Question 11

CSF abnormalities in bacterial meningitis

Answer 11

Presence of PMNs
Decreased glucose

Increased protein

Increased pressure

Question 12

CSF abnormalities of viral meningitis/encephalitis

Answer 12

Monocytes and lymphocytes
Normal glucose

Normal/slightly increased protein pressure

Question 13

Treatment of bacterial meningitis

Answer 13

Empirical antibiotic therapy

Using diagnostic tests can help determine most effective drug

Question 14

Bacterial meningitis causative agents

Answer 14

S. pnuemo
N. meningitidis

S. agalactiae

Listeria monocytogenes

H. influenzae

Question 15

S. pneumo features

Answer 15

Gram-positive cocci in chains
Catalase negative

Alpha-hemolytic

Susceptible to optochin and bile

Question 16

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

Answer 16

Pneumococcal meningitis

Question 17

Pneumococcal virulence factors

Answer 17

Choline binding proteins
Pneumolysin

IgA protease

Capsule

Question 18

Choline binding proteins

Answer 18

Allows for colonization in the oropharynx

Question 19

Pneumolysin

Answer 19

Inhibits mucociliary clearance

May also interfere with macrophage clearance

Question 20

Pneumococcal meningitis clinical importance

Answer 20

Acute onset
High mortality

Neurological sequela

Question 21

Pneumococcal meningitis recommended therapy

Answer 21

Vancomycin with a cephalosporin

Modify when organism is identified

Question 22

Pneumococcal polysaccharide vaccine (PPV)

Answer 22

Capsular polysaccharide Ag from 23 types of pneumococcus

Does not prevent pneumonia as effectively

Question 23

Who should get the PPV?

Answer 23

Adults > 65 years old

Anyone > 2 years old with increased risk

Question 24

Pneumococcal conjugate vaccine (PCV13)

Answer 24

Pneumococcal capsule (13 serotypes) conjugated to nontoxic diphtheria toxin

Question 25

Who should get the PCV13?

Answer 25

Routine child vaccine | 2, 4, 6 months, then booster at 12-15 months

Question 26

N. meningitides features

Answer 26

Gram-negative diplococcus Oxidase and catalase positive Oxidizes BOTH glucose and maltose Fastidious, requiring CO2

Question 27

N. meningitides virulence factors

Answer 27

Capsule | LOS

Question 28

N. meningitides transmission

Answer 28

~10% of population is colonized | Transmission is via aerosolized droplets

Question 29

Which serotypes cause almost all invasive meningococcal disease?

Answer 29

C B Y W-135 A

Question 30

N. meningitides virulence factors

Answer 30

Pilli Capsule LOS

Question 31

LOS effects

Answer 31

Inflammation/immune response Endotoxemia (organ failure) DIC

Question 32

N. meningitides entry into CNS

Answer 32

BBB weakened | Cross BBB WITHIN neutrophils

Question 33

What is meningococcemia?

Answer 33

Bloodstream infection occurring with or without meningitis

Question 34

Meningococcemia Sx

Answer 34

Fever Petechial/purpuric rash Hypotension Multiorgan failure

Question 35

What causes meningococcal meningitis?

Answer 35

Hematogenous dissemination

Question 36

Diagnose meningococcal meningitis

Answer 36

Gram-stain of CSF and/or blood Bacteremia Susceptibility testing

Question 37

Treatment for meningococcal meningitis

Answer 37

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

Question 38

Meningococcal polysaccharide vaccine (MPV)

Answer 38

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

Question 39

Who should get the MPV?

Answer 39

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

Question 40

What defines a meningococcal outbreak?

Answer 40

3+ cases in < 3 months

Question 41

Meningococcal conjugate vaccine (MCV4)

Answer 41

Tetravalent against A, C, Y, and W-135 (B still on the way) | Conjugated to nontoxic diphtheria toxin subunit

Question 42

Who should get the MCV4?

Answer 42

Anyone 11-55 | 9 months-55 years that have increased risk factors

Question 43

Differences between MPV and MCV4?

Answer 43

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