Lecture 28: Fever and headache

Question 1

Definition of meningitis?

Answer 1

An increase in WBC in the CSF within the subarachnoid space of the brain and brainstem. It is due to inflammation and is most commonly viral meningitis and is benign and seld-limiting.

Question 2

Causes of meningitis?

Answer 2

• Main cause are enteric viruses that are swallowed (like influenza and herpes)
• Bacterial meningitis is less common but far more serious. (main causes are N meningitidis and Streptococcus pneumoniae)
• fungi are rare and mostly only found in people with cancer or AIDS
• Protozoa are rare especially in non-third world countries
• Other: drugs, trauma, neurosurgery, cancer

Question 3

Inflammation of meninges causes?

Answer 3

• Headache
• photophobia
• neck stiffness
• drowsiness

But these are commonly late and earlier in the piece they present with:

• rash
• leg pain

Question 4

Bacterial meningitis cause? risk factors?

Answer 4

Illness is preceeded by nasopharyngeal colonisation as 10-20% of young adults being colonised with N. meningitidis

Bacteria enter the subarachnoid space and propogate

Question 5

Diagnosis of Meningitis?

Answer 5

• Clinical suspicion (symptoms can be vague early in the illness with signs of meningits appearing late in the illness)
• CSF fluid sample (L4/5 sample and pressure)
• Blood cultures
• Throat swap
• Blood to detect bacterial DNA by PCR
• Leg lift = Kernig’s sign with sore neck rather than sore hamstrings due to pulling on the cauda equina.

Question 6

Differences in CSF components with viral and bacterial infection?

Answer 6

Question 7

epidemiology?

Answer 7

Most of cases are found in people below the age of 5 especially below 1. The main brunt of the disease is within maori and pacific island children.

The mortality is stable at around 7% of all cases

Question 8

How does N. meningitidis avoid the immune system?

Answer 8

N meningitidis is a gram negative cocci

N meningitidase can coat itself in a layer that prevents C3 convertase from being formed

+ many more ways of interfeering with the complement cascade

Question 9

Concequences of high levels of lipopolysaccharides?

Answer 9

Platelets detect this and send signals to neutrophils to commit suicide and release their DNA

Their DNA forms a meshwork within small blood vessels as a way of trying to localise the infection

This is a physiological response to sepsis and causes clotting of small capillaries. This interferes with organ function massively.

• Drwosiness
• Confusion
• Fever
• Ahes and pains
• Clammy and grey skin
• Kidney and clotting failure

Question 10

Order of managemement for bacterial meningitis? Viral meningitis?

Answer 10

Bacterial

• Give IV antibiotics
• Resuscitate
• Take blood cultures
• Transfer to hospital

Viral

• reassure them they will be fine
• Analgesia
• Can usually recover at home

Question 11

What are cephalosporins?

Answer 11

They are antibiotics derived from the mould Acremonium and are very similar in structure to penicillins

Generation:

1 - cefazolin = used for hip transplants and what not

2 - Cefuroxime used like lolly water agaisnt staph, strep and E. coli

3 - Ceftriaxone is really agaisnt E coli and its cousins as well as pseudomonis bacteria (but not agaisnt staph aureus and strep)

4 - Cefepime, cefpirome are v v broad “fumagating agents”

5 - ceftaroline - now used in NZ against MRSA

Question 12

Treatment (antibiotics) for bacterial meningitis?

Answer 12

Some places will recommend ceftriaxone (cephalosporin) and this does work well and achieves moderate concentrations in CSF and has a broad spectrum of activity. (They have some cross-over in anaphylaxis if the person is anaphylactic to penicillin but it’s low so use ceftriaxone if anaphylactic to penecillin)

At Auckland city hospital Penicillin is used as ceftriaxone as it will kill off lots of other bacteria in the person.