CSF

Question 1

How many CSF samples should be taken and why?

Answer 1

Best practice to take 3+ samples
3+ samples required for a serial red cell count

This might not always be possible, depends on how well the patient can tolerate it etc
Might get 5+ samples depending

Question 2

Why do we do a serial red cell count

Answer 2

Gives us information on how traumatic a tap was

Red cells should be highest in the first sample but should decrease with each sample

Question 3

What would high red blood cells in each sample indicate

Answer 3

Subarachnoid haemorrhage

Question 4

Why would a random sample have an increased red cell count

Answer 4

Might be due to movement of the patient or movement of the needle etc

There might be high red cells in 2 or 3 of the samples if there was poor access etc

Question 5

When do we a serial red cell count

Answer 5

Done on all samples as long as there is 3+ samples

Question 6

If you have 6 CSF samples which ones do you use? Why?

Answer 6

Use the last three samples
i.e. the ones labelled 4, 5, 6

Least amount of red blood cell contamination

Question 7

How do we process a CSF sample

Answer 7

Describe the appearance of all CSF samples

White cell count + Diff if necessary

Supplemental tests

Question 8

How do we describe the appearance of CSF

Answer 8

Colourless
Blood stained
Xanthochromia
Spider-web clot

Question 9

What does Xanthochromia mean?

Answer 9

Straw coloured CSF

Due to the breakdown of bilirubin

Question 10

What does a spider web clot in a CSF indicate?

Answer 10

TB meningitis

Question 11

What sample do we carry out a white cell count on? Why?

Answer 11

Last sample

Most accurate count, it’s directly from patient, least contamination

Question 12

What is considered a high white cell count for CSF?

Answer 12

White cell counts of 5 or higher

Question 13

What is considered a high red cell count?

Answer 13

Red cell count of 10 or higher

Question 14

What would a CSF with a wcc >5 look like?

Answer 14

Cloudy in appearance

Question 15

What can be done if the red blood cells are really high? Why

Answer 15

Use Turk’s solution

This dissolves any red blood cells

This allows for a more accurate white blood cell count

Question 16

What do we do if a white blood cell count is greater than 5?

Answer 16

We carry out a differential stain

Question 17

How do we carry out a differential stain?

Answer 17

Count the number of mononuclear cells versus polynuclear cells

Question 18

What does high mononuclear cells in a CSF diff mean

Answer 18

Viral infection

Question 19

What does high polymorphonuclear in a CSF diff mean?

Answer 19

Bacterial infection

Question 20

Do we do gram stains for CSF?

Answer 20

No gram stains
We do a film array instead

Question 21

Give some examples of internal supplemental test

Answer 21

Biochemistry for protein and glucose
Immunology for monoclonal bands

Question 22

Give some examples of send outs

Answer 22

MS investigation -> send out to UK

Alzheimer’s investigation -> send out to UK

Xanthochromia -> samples sent to Beaumont in a dark tube or wrapped in tinfoil

Query CJD sent out to Beaumont

Beta-2-transferrin sent to UK

Question 23

How are glucose and protein affected in bacterial vs viral infection?

Answer 23

Glucose decreased and protein increased during bacterial infection

Less of an impact seen during viral infection -> increased protein only

Question 24

Why might we test for Beta-2-transferrin?

Answer 24

Used to test if a sample contains any CSF

Maybe a patient has a query CSF leakage -> want to confirm is CSF

Non done in house, sent to the UK

Question 25

When do we culture CSF

Answer 25

Only done if cultures are wanted -> bacterial meningitis No need if viral meningitis etc

Question 26

What do we culture CSF on

Answer 26

Chocolate and blood agar

Question 27

When do we read CSF plates

Answer 27

Read twice Once after 24 hours Once after 48 hours

Question 28

What discs do we put up on CSF plates?

Answer 28

No discs If any colony grows its significant

Question 29

Why might we not see any growth when we culture CSFs up

Answer 29

Patients are nearly always on antibiotics already This is why we use the film array

Question 30

What is the principle behind the film array?

Answer 30

Nested PCR

Question 31

What are the benefits and disadvantages of using Film Array?

Answer 31

Useful for CSFs which are usually culture negative Only downfall is that sensitivities cannot be done

Question 32

What film array panels do we use

Answer 32

Two panels: - Meningitis/Encephalitis panel - Respiratory panel

Question 33

When do we use the film array respiratory panel?

Answer 33

▪ Done for someone suffering from flu symptoms who is Covid negative and GeneXpert negative ▪ Not very common, only done to try and figure out what exactly the patient has Panel containing covid and adenovirus etc

Question 34

What do we do if the film array is unable to type the virus?

Answer 34

We send the sample to the NVRL for typing

Question 35

What should we be looking for in CSF for HIV/Transplant patients

Answer 35

Cryptococcus We do a cryptococcus antigen screen on all newly diagnoses HIV patients

Question 36

What are the common causes of bacterial meningitis in adults

Answer 36

H. influenzae S. pneumoniae N. meningitidis

Question 37

What is the most common cause of viral meningitis?

Answer 37

70% is enterovius

Question 38

What are some different types of meningitis

Answer 38

Bacterial Viral Cryptococcal meningitis TB meningitis -> very rare in Ireland

Question 39

What are some common causes of meningitis in MMUH

Answer 39

S. pneumoniae Haemophilus. influenzae Neisseria species including N. gonorrhea Enterovirus Herpes caused meningitis

Question 40

What would indicate a cryptococcal infection?

Answer 40

Large volume of CSF 6+ samples etc

Question 41

What is the most common cause of meningitis in children?

Answer 41

Adenovirus