CNS infections - Cellular Pathogens

Question 1

what is the typical cause of non-bacterial meningitis?

Answer 1

viral pathogen. typically enteroviruses

Question 2

what is cause of aseptic meningitis?

Answer 2

anything non-bacterial cause (ie virus, inflammatory conditions, etc)

Question 3

3 most pathogenic causes behind meningitis (infants/ children/adults? typical origin?

Answer 3

H. influenza,
Neisseria meningitidis,
haemophilius influenzae (type B)

All of these come from nasopharynx.

Question 4

3 most common pathogenic causes of meningitis in neonates? origin?

Answer 4

E. coli (and other gram neg bacilli),
Group B streptococcus
Listeria monocytogenes

All of these come from the birth canal (ie from the gut)

Question 5

how might meningitis infections develop?

Answer 5

pathogen colonizes nasophrynx.
invasion of blood stream and multiplication.
crosses BBB
invasion of meninges and CNS
increased permeability of BBB
pleocytosis and increased ICP
release of pro-inflammatory compounds
-->neuronal injury

Question 6

what are the symptoms/signs of a neonate/toddle suffering from meningitis?

Answer 6

fever, vomiting/nausea, irritable/unsettled, refusing food/drink

altered mental state
bulging fontanelle

Question 7

what is characteristic sign of nisseria meningitis infection?

Answer 7

meningococcaemia produces a petechial or purpuric rash

Question 8

what are normal csf values for WBC, RBC, pressure, protein and glucose?

Answer 8

Pressure 2.5 mmol/L (>60% blood)

Question 9

what might a csf analysis of viral meningitis show?

Answer 9

normal clear appearance,
normal glucose, 
normal protein, 
gram negative, 
pressure normal,
lots of lymphocytes (100s)

Question 10

what might a csf analysis of bacterial meningitis show?

Answer 10

raised pressure,
cloudy appearance,
1000s of N,
gram stain positive,
protein high,
glucose low

Question 11

what might a csf analysis of TB meningitis show?

Answer 11

raised pressure,
cloudy appearance,
100's of lymphocytes,
ziehl-neelsen stain positive
very high protein
glucose very low

Question 12

when should a lumbar puncture not be performed in children/young adults with suspected meningitis

Answer 12

-signs of raised ICP (fluctuating levels of conciousness, relative bradycardia, focal neurological signs, poorly responsive pupils)–>will cause herniation of brain stem through foramen magnum

• shock
• extensive/spreading purpura
• after convulsions (until stabilized)
• coagulation abnormalities

Question 13

what are the dangers of delaying analysis of a csf sample?

Answer 13

cells lyse in hypotonic fluid, white cell count decreases, causing a false negative

Question 14

what are treatment priorities for meningitis?

Answer 14

• resuscitation/life support
• fluids
• Abx
• Steroids at least 15 min prior to 1st Abx dose or within 1hr of 1st abx dose.
• contact prophylaxis

Question 15

what Abx would you use to empirically treat infant/children/adults with suspected bacterial meningitis?

Answer 15

IV dose 3rd gen cephalosporin (cefotaxime or ceftriaxone)

…against usual pathogens of nisseria, haemophilius influenzae type B or strep pneumoniae.

Question 16

what Abx would you use to empirically treat neonates with suspected bacterial meningitis?

Answer 16

Group B Strep or Listeria can be treated with IV penicillin or gentamicin.

E. coli can be treated with IV dose 3rd gen cephalosporin (cefotaxime or ceftriaxone)

Question 17

most common neuronal injury following meningitis?

Answer 17

deafness/hearing loss

Question 18

which bacterial pathogen group has the highest incidence of causing neuronal injury with meningitis

Answer 18

meningococcus bacteria