Meningitis pt.1

Question 1

What is meningitis?

Answer 1

Inflammation of the meninges

Question 2

What are the meningies?

Answer 2

Three membranes that cover the brain and spinal cord and include (from most superficial to deepest):

• Dura mater
• Arachnoid mater
• Pia mater

Question 3

Where is the CSF found?

Answer 3

It is found in the subarachnoid space found between the pia and arachnoid mater

Question 4

Aside from the arachnoid space, what other anatomical space can found in the CNS?

Answer 4

A potential space known as the subdural space and according to some authors, it contains a very thin layer of fluid

Question 5

Where is the main site of meningitis infection?

Answer 5

The subarachnoid space with involvement of the CSF

Question 6

According to the appearance of the CSF, how can one differentiate between possible etiologies of meningitis?

Answer 6

• Transparent CSF suggests a viral meningitis

- Purulent (cloudy) CSF suggests a bacterial meningitis

Question 7

What are the possible infectious etiologies of meningitis?

Answer 7

They include viral, bacterial, fungal, parasitic/protozoal

Question 8

What are examples of parasitic/protozoal organisms that can cause meningitis?

Answer 8

They include:

• Plasmodium
• Toxoplasma
• Amoeba (Naegleria fowleri)
• Angiostrongylus
• Hydatid
• Cysticercosis (Taenia solium tapeworm)

Question 9

What are examples of fungal organisms that can cause meningitis?

Answer 9

They include:

• Cryptococcus
• Histoplasma
• Aspergillus
• Candida
• Mucormycosis
• Coccidiosis

Question 10

What is the most common etiological form of infectious meningitis?

Answer 10

Viral is the most common, followed by bacterial (still common), with fungal and parasitic/protozoal being rare

Question 11

What are the most common bacteria causing bacterial meningitis?

Answer 11

They include:

• Streptococcus pneumoniae
• Group B Streptococcus
• Neisseria meningitidis
• Haemophilus influenzae
• Listeria monocytogenes
• Escherichia coli

H. Influenzae b, S. pneumoniae, N. meningitidis
cause together 75-80% of all bacterial meningitis

Question 12

What is considered to be the most important bacterium causing meningitis?

Answer 12

Haemophilus influenzae

Question 13

What type of bacteria is Haemophilus influenzae?

Answer 13

Gram negative facultative anaerobic capnophilic coccobacillary

Question 14

What is a facultative anaerobic organism?

Answer 14

An organism that makes ATP by aerobic respiration if oxygen is present, but is capable of switching to fermentation if oxygen is absent

Question 15

Is Haemophilus influenzae preventable?

Answer 15

Yes, vaccination is available

Question 16

Which age group does Haemophilus influenzae affect?

Answer 16

Mostly children 6 months to 4 years old

Question 17

What type of bacteria is Neisseria Neisseria meningitidis?

Answer 17

Gram negative aerobic capsuled diplococci

Question 18

What is another name for Neisseria meningitidis?

Answer 18

Meningococcus

Question 19

What does capnophilic organisms?

Answer 19

Microorganisms that thrive in the presence of high concentrations of carbon dioxide (CO2)

Question 20

How common is the neisseria meningitidis bacterium in the population?

Answer 20

• Widespread in general population

- Estimated to be found in the nasopharyngeal flora of 3% to 25% of healthy individuals

Question 21

Where is neisseria meningitidis bacterium found in carriers?

Answer 21

Mostly found in the naso-pharynx

Question 22

Which serogroup of neisseria meningitidis is most common in the United States and Europe?

Answer 22

Serogroup B in the USA and Serogroup C in Europe

Question 23

Who is neisseria meningitidis vaccine recommended to?

Answer 23

• Universally recommended beginning at age 11 with boosters at 16 years
• It is also recommended down to the age of 9 months for anyone at high risk for meningococcal
  disease (complement deficiency, asplenia, HIV infection)
  -

Question 24

What are the serogroups of neisseria meningitidis based on?

Answer 24

Serogroups are based on the

polysaccharide capsule

Question 25

Which neisseria meningitidis serotypes are the most clinically relevant?

Answer 25

- The most important disease-producing serogroups are A, B, C, W-135, and Y - Group A causes widespread epidemics

Question 26

How N.meningitidis transmitted?

Answer 26

Transmission occurs by inhalation of aerosolized respiratory droplets

Question 27

What promotes transmission of N.meningitidis?

Answer 27

- Close, prolonged contact such as occurs in families and closed populations promotes transmission. - The estimated attack rate among family members residing with an index case is 1000 times higher than in the general population; this fact is evidence of the contagious nature of meningococcal infection - Other factors that foster transmission are contact with a virulent strain and host susceptibility (lack of protective antibody)

Question 28

What are typical settings of large N. meningitidis outbreaks?

Answer 28

Typical settings of larger outbreaks are schools, dormitories, and camps for military recruits. In these close living circumstances, N meningitidis spreads readily among newly exposed individuals, but disease develops only in those who lack group-specific antibody.

Question 29

What are problems with the current meningococcal vaccine?

Answer 29

- Does not protect against serogroup B (failure of the group B polysaccharide to be immunogenic at all, recognized as self by the host), Group B causes up to one-third of all disease, so no vaccine that omits it is likely to be completely successful - The “hole” created by absence of a group B component could have epidemic potential - There is less experience with these protein-conjugate vaccines which is why the recommended starting age is 11. In practice the age is being slowly and cautiously dropped down

Question 30

How can disease arise in individuals in contact with N. meningitidis?

Answer 30

Disease may be endogenous (respiratory microbiota) or transmitted from a case by respiratory droplets

Question 31

What is the current vaccine against N.meningitidis?

Answer 31

Meningococcal Conjugate Vaccine Quadrivalent (MCV4) which protects against serotypes A, C, Y, and W-135

Question 32

Which age group does N.meningitidis affect?

Answer 32

Most disease occurs in children 6 months to 5 years old ( 6 months and 2 years of age being the peak) with a second peak at 18 to 25 years of age