Microbiology 5 - CNS infections and meningitis

Question 1

Which antibiotic should be used first line in meningitis?

Answer 1

Ceftriaxone

Question 2

If listeria meningitis is suspected, what antibiotic therapy should be used?

Answer 2

Ceftriaxone plus amoxicillin

Question 3

Which pathogen is most likely to be the cause in myelitis?

Answer 3

Poliovirus

Question 4

What is myelitis?

Answer 4

Inflammation of the spinal cord

Question 5

Recall the 3 most likely causative organisms in acute meningitis, and the most susceptible demographic of patient to each

Answer 5

N. meningitidis = young
S. pneumoniae = elderly (so vaccine at 65 years)
H. influenzae = those who haven’t had HiB vaccine

Question 6

What is the most commonn cause of meningitis in neonates?

Answer 6

Group B strep

Question 7

What is the most likely causative organism in chronic meningitis?

Answer 7

TB

Question 8

What is the most likely causative organism in aseptic meningitis?

Answer 8

Coxsackie virus

Question 9

Describe the rash produced by meningococcal meningitis

Answer 9

Non-blanching purpuric rash

Question 10

What is the most likely viral cause of encephalitis in the UK and worldwide?

Answer 10

UK: HSV
Worldwide: WNV

Question 11

Recall 3 possible routes of infection that may cause a brain abscess

Answer 11

Direct expansion from

• otitis media
• mastoiditis
• paranasal sinusitis

Question 12

What is the most common type of spinal vertebral infection?

Answer 12

Pyogenic vertebral osteomyelitis

Question 13

What is the most common cause of pyogenic vertebral osteomyelitis?

Answer 13

Infective endocarditis - staph/ strep can be ‘flicked off’ the valve

Also can be due to spinal surgery/trauma

Question 14

What is the first investigation to do in suspected meningitis?

Answer 14

Blood cultures

Question 15

Recall the stains used in CSF analysis to look for a) bacteria b) TB and c) fungi

Answer 15

a) gram stain
b) auramine stain
c) India ink

Question 16

If “alpha haemolytic diplococci” are found in CSF, what is the pathogen causing meningitis?

Answer 16

Streptococcus pneumoniae

Question 17

What is the normal range for CSF protein?

Answer 17

0.15-0.4

Question 18

What is the appearance of CSF in purulent vs aseptic vs TB meningitis?

Answer 18

Purulent: turbid

Aseptic/ TB: slightly turbid or clear

Question 19

What type of cell is elevated in the CSF in purulent vs aseptic vs TB meningitis?

Answer 19

Purulent: polymorphs

Aseptic/ TB: lymphocytes

Question 20

In which type of meningitis will gram stain antigen tests be positive?

Answer 20

Purulent meningitis

Question 21

Which type of meningitis produces the most protein in CSF?

Answer 21

TB meningitis

Question 22

What is the empirical therapy for meningitis?

Answer 22

Ceftriaxone 2g IV bd

Add amoxicillin if >50 or immunocompromised or listeria is supsected