Meningitis

Question 1

Is bacterial or viral meningitis more common? Who is each more common in?

Answer 1

Viral meningitis is more common

Viral is more common in children, and bacterial is more common in adults since introduction of the Hib vaccine

Question 2

As bacteria replicate in the subarachnoid space, what are two major effects the release of bacterial components (i.e. LPS) will cause?

Answer 2

1. Dilation of cerebral microvascular epithelium

2. Stimulation of macrophages and neutrophils, which release inflammatory cytokines

Question 3

What is vasogenic edema?

Answer 3

Edema caused by increased permeability of blood brain barrier, leads to increased ICP, especially due to exit of proteins from the blood into the CSF leading to increased oncotic pressure

Basically, edema caused by “vaso” or vessels opening

Question 4

What is interstitial edema?

Answer 4

Increased resistance to CSF outflow due to inflammation of the subarachnoid space leads to increased ICP and breakage of blood-CSF barrier, but will NOT cause a protein increase

Basically, edema caused by excess CSF

Question 5

What is cytotoxic edema?

Answer 5

Increased intracellular pressure buildup due to loss of ion gradients, often following subarachnoid inflammation

Basically, edema within the neuronal cell rather than interstitial space

Question 6

Why is increased ICP really a problem?

Answer 6

Leads to decreased cerebral blood flow and loss of cerebrovascular autoregulation

Question 7

What can extended subarachnoid space inflammation due to the blood vessels in the brain?

Answer 7

Causes cerebral vasculitis

Question 8

What is the main pathogenic factor that facilitates entrance into the CSF? What is the host defense?

Answer 8

Fimbriae, and association with macrophages

Host defense: Blood-CSF barrier

Question 9

What is the main pathogenic factor that allows survival in the CSF? What is the host defense?

Answer 9

Polysaccharide capsule

Host defense would be humoral + complement-mediated, however there is poor antibodies in the CSF so there is no defense!

Question 10

What is the difference between early and late onset GBS infection?

Answer 10

Early: <7 days, highly preventable
Late: Nosocomial or community-borne (up to 1 month)

Question 11

What are the top 5 microbes causing CNS infection in 1-23 month olds?

Answer 11

1. Group B strep
2. E. coli K1
   (listeria falls off the list)
3. Strept pneumoniae
4. Hib (vaccine not completed yet)
5. Neisseria meningitidis

Question 12

What are the top 2 microbes causing meningitis from 2 years to 18 years?

Answer 12

1. N. meningitidis (most common cause among teens)

2. S. pneumoniae

Question 13

What are the top 2 microbes causing meningitis from 18 to 50 years?

Answer 13

1. S. pneumoniae (most common cause among adults)

2. N. meningitides

Question 14

How do the microbes causing meningitis differ past age 50?

Answer 14

Same top two, but a return of Listeria (immunocompromization with age) and aerobic gram negatives like E. coli

Question 15

What species most commonly cause meningitis following head trauma / post neurosurgery?

Answer 15

Staphylococcus aureus and epidermitis.

Aerobic gram negatives as well including P. aeruginosa and E. coli

Question 16

What causes meningitis in basilar skull fracture / CSF leak?

Answer 16

S. pneumonia
H. influenza
Group A Strept

Question 17

What are the most common clinical findings of meningitis in adults?

Answer 17

Neck stiffness (nuchal rigidity), fever, mental status change (depression), focal neurologic finding (indicates cerebral vasculitis), or rash (from Neisseria meningitidis)

Question 18

How do neonates / infants / non-verbal children present differently with meningitis than adults?

Answer 18

More subtle presentation, including fever, irritability, poor feeding, and bulging fontanelle is an important finding

Question 19

What are important predisposing factors to meningitis?

Answer 19

OPS of MOPS, although direct seeding has not been shown,

Endocarditis, recent head trauma / CSF leak, immunosuppression or splenic dysfunction, alcoholism, complement deficiency

Question 20

What complement deficiency puts you at a greater risk for meningitis?

Answer 20

Deficiency of C5-C9 (think Noir 5-9pm)

Question 21

What is done to diagnose meningitis?

Answer 21

Lumbar puncture

Question 22

What is needed to be done before LP in some patients?

Answer 22

Neuroimaging (CT) scan, especially in immunocompromised or when we’re concerned for stroke

Question 23

What are typical parameters you want to measure from CSF?

Answer 23

1. Opening pressure (ICP)
2. Protein
3. Glucose (with comparative simultaneous serum glucose)
4. Cell count
5. Bacteria / viral detection

Question 24

What is typically used for bacterial and viral detection?

Answer 24

Bacteria - latex agglutination, gram stain, or multiplex PCR

Viral - PCR

Question 25

Other than antibiotics which penetrate CSF well, what other drugs do we give patients with meningitis and why?

Answer 25

Corticosteroids - reduce inflammation to reduce ICP and prevent sensorineural hearing loss

Question 26

What is used to prevent meningitis?

Answer 26

Antibiotic prophylaxis for close contacts (Rifampin)

Vaccines including meningococcal, Hib, pneumococcal, and GBS antibiotics in pregnancy

Question 27

What is pleocytosis?

Answer 27

Increased number of WBCs in CSF

Question 28

What is the characteristic pleocytosis in aseptic meningitis?

Answer 28

Predominantly lymphocytic (T/B cells), with bacterial stain and cultures being negatively

Question 29

What is the most common cause of viral meningitis and who gets it?

Answer 29

Typically associated with enteroviruses, most common in infants / young children in late summer and early fall

Question 30

What WBC type are bacterial infections most likely to have in the CSF and how high is the total count?

Answer 30

Usually over >1,000 WBCs per mL, with >50% being PMNs

Question 31

What WBC type are viral infections most likely to have in the CSF and how high is the total count?

Answer 31

Usually over >1,000 WBCs per mL, with <50% being PMNs, except in early stages

Question 32

Are you expected to have increased protein in viral meningitis?

Answer 32

No, or only slightly elevated.

Only bacterial infections have >100 mg/dl protein

Question 33

What is the expected CSF vs serum glucose in bacterial meningitis?

Answer 33

<50% of serum glucose, important to get simultaneous glucose especially in diabetics

Question 34

What are some non-infectious causes to meningitis?

Answer 34

Autoimmune diseases like Lupus and Rheumatoid arthritis

Drugs such as NSAIDS, TMP/SMX, carbamazepine

Question 35

Do Patty Brown’s Case Studies on Blackboard

Answer 35

You fak fak