CLINICAL WORKSHOP: Meningitis Microbiology

Question 1

A sample of what is taken when you suspect meningitis?

Answer 1

CSF
throat swab
blood test
aspirate

Question 2

What does a normal CSF sample look like?

Answer 2

clear water colour

Question 3

What does CSF look like in a meningitis sample?

Answer 3

milky

Question 4

Why does the sample look milky?

Answer 4

• full of protein

- full of WBCs

Question 5

What is the protein level in CSF of meningitis person?

Answer 5

• Normal CSF are between 0.15 and 0.4g/L

- Meningitis CSF: higher protein than normal e.g. 0.8g/L

Question 6

What is the glucose level in the CSF of a meningitis person?

Answer 6

• normal CSF glucose= between 0.3 and 3g/L

- bac meningitis CSF glucose= low CSF glucose (example 0.3g/L)

Question 7

What is the white cell count in the MENINGITIS CSF?

Answer 7

normal: between 0 and 7 white cells; 80% lymphocytes

bac meningitis: eg 540 cells, 80% neutrophils

Question 8

Under a microscope, what do you see in the CSF?

Answer 8

• after gram staining, neutrophils and bacteria are visible

- bean shaped gram negative diplococci sitting inside and outside of the neutrophils

Question 9

Where can N Meningitis survive?

Answer 9

in macrophages

Question 10

What are the 3 main organisms that can cause bacterial meningitis in children?

Answer 10

• neisseria meningitidis
• haemophilus influenza type B
• streptococcus pneumoniae

Question 11

What is neisseria meningitidis?

Answer 11

• gram negative bacteria
• diplococci
• oxidative activity POSITIVE
• no haemolysis shown on a blood agar plate

Question 12

What is haemophilus influenza type B?

Answer 12

• gram negative bacteria
• bacillus
• oxidative activity NEGATIVE
• NO haemolysis shown on blood agar plate

Question 13

What is streptococcus pneumoniae?

Answer 13

• gram positive
• diplococci
• oxidative activity NEGATIVE
• SHOWS alpha haemolysis on blood agar plate

Question 14

Why is the incidence of bacterial meningitis less?

Answer 14

because there are vaccinations against all 3 types of bacteria that cause meningitis

Question 15

In neonates, what other bacteria found in the CSF can be the cause of meningitis?

Answer 15

• E coli
• listeria
• group B haemolytic streptococcus

Question 16

Why is a culture of the CSF done?

Answer 16

• CSF has a lot of protein
• hard to see microorganisms inside it
• set up CSF for culture to grow on blood agar plate

Question 17

What is a CSF culture done for?

Answer 17

• determine antibiotic susceptibility

Question 18

What happens in a blood culture?

Answer 18

1. many bottles used with aerobic and anaerobic enviroonments
2. bottles show if culture is successful by turning red (CO2) is an indicator
3. bacteria then plated on blood agar plate
4. look at colonies
5. can also plate bacteria on chocolate agar (heated blood agar)
6. add oxidase reagent
7. colonies turn blue showing positive result