meningitis

Question 1

describe each cause of meningitis

Answer 1

viral

• common, mostly benign
• spontaneously improves
• influenza (mainly A), enterovirus

bacterial

• common, serious
• N. meningitis or S. pneumoniae
• (M. TB = rarer)
• illness preceded by nasopharynx colonisation

fungi

• rare
• usually only in AIDs

Question 2

presentation

Answer 2

• headache
• sometimes photophobia
• neck stiffness
• drowsiness
• also systemic systems = fever, septic shock, rash

Question 3

diagnosis of meningitis

Answer 3

• clinical suspicion (signs appear late)

- samples = CSF, blood culture, throat swab, blood to detect bacterial DNA by PCR

Question 4

kernigs sign

Answer 4

lift legs up, bending at the hips, if headache worsens = meningitis

Question 5

streptococcal antigen test

Answer 5

shows if S. pneumoniae is present. Colour change when antigen binds to card

Question 6

lumbar puncture

Answer 6

• take CSF between L4/5 spinous process. fluid drawn from subarachnoid space

Question 7

what difference will viral vs bacterial CSF have

Answer 7

Bacterial

• increased protein
• decreased glucose
• increased neutrophils
• increased WBC

viral

• normal glucose
• increased or normal protein
• increased WBC
• increased lymphocytes

Question 8

describe PCR testing

Answer 8

• amplifies a single coy or a few copies of a segment of DNA
• tests for nucleic acid (tests S. pneumoniae DNA in CSF)
• doesn’t require live bacteria
• used when pathogens can’t be cultivated easily

Question 9

n meningitidis

Answer 9

characteristic rash, transforming into large petechiae (however no rash doesn’t exclude)

CSF gram stain negative = single layer peptidoglycan

Question 10

pathogenic mechanisms of N. meningitidis

Answer 10

• polysaccharide capsule prevents opsonisation and phagocytosis
• protein binds factor H (down-regulates complement)
• bacteria produces lipopolysaccharides to release in bloodstream (avoids complement)
• C4 binding protein prevents cleavage of C3

Question 11

development of shock

Answer 11

1. when bacteria load is very high neutrophils commit suicide
2. release their DNA into capillaries
3. DNA forms nets in capillaries, trapping circulating bacteria & immune cells
4. decreases BF to organs causing shock

Question 12

treatment for bacterial

Answer 12

• give IV antibiotics (penicillin)
• resuscitate
• take blood culture when IV inserted
• transfer to hospital
• investigations
• pain relief, fluids, IV antibiotics

Question 13

treatment for viral

Answer 13

• reassurance
• analgesia
• can usually recover at home

Question 14

treatment for patients in shock

Answer 14

maintain organ perfusion
- IV fluids, oxygen

resolve infection
- antibiotics, surgery

early recognition important

Question 15

cephalosporins

Answer 15

• derived from mould acremonium
• works in the same way as penicillin but with an extra carbon ring
• 3rd generation = ceftriaxone