Bacterial and fungal meningitis

Question 1

What are the features of Neisseria meningitidis?

Answer 1

Gram negative diplococci

Require blood for growth (chocolate agar)

13 capsular types: A, B, C, W135, Y most common

Can also be detected by nucleic acid amplification (PCR)

Question 2

What are the main differences between the clinical presentations on meningitis and encephalitis?

Answer 2

Focal neurology and confusion absent in meningitis; present in encephalitis.

Question 3

What is the natural habitat of N. meningitidis?

Answer 3

Nasopharynx - not all strains encapsulated (capsule is a virulence factor)

Question 4

What factors make N. meningitidis more likely to survive in the bloodstream?

Answer 4

Presence of capsule

Acquisition of iron from ferritin

Question 5

What are the possible presentations of N. meningitidis infection?

Answer 5

Fulminant septicaemia (no CNS infection)

Septicaemia with purpuric rash (no CNS infection)

Septicaemia with meningitis

Pyogenic (purulent) meningitis with no rash

Chronic meningococcal bacteraemia with arthralgia

Focal sepsis

Conjunctivitis, endophthalmitis

Question 6

What treatment is given can be given for N. meningitidis infection?

Answer 6

Ceftriaxone, cefotaxime
Penicillin
Intensive care management

Question 7

What chemoprophylaxis is given to close contacts of N. meningitidis infection?

Answer 7

Rifampicin

Ciprofloxacin

Question 8

What are the features of Haemophilus influenzae?

Answer 8

Small, pleomorphic, Gram negative cocco-bacilli or bacilli

Some strains produce a polysaccharide capsule

Six antigenic types a-f

Type b causes the most invasive disease

Cannot grow in the absence of blood

Question 9

What is the normal carriage of H. influenzae?

Answer 9

Restricted to humans

25-80% carry non-capsulate strains

5-10% carry capsulate strains

Nasopharynx

Question 10

How does H. influenzae reach the bloodstream?

Answer 10

Throat carriage – invasion of submucosa – blood stream

Question 11

What are the H. influenzae virulence factors?

Answer 11

Type b capsule

Fimbriae

IgA proteases

Outer membrane proteins/lipolysaccharide

Question 12

What treatment is given for H. influenzae?

Answer 12

Ceftriaxone, cefotaxime

Ampicillin

β-lactamase producing strains common

Question 13

What chemoprophylaxis is given to close contacts of H. influenzae patients?

Answer 13

Rifampicin

Question 14

What are the features of Streptococcus pneumoniae?

Answer 14

Gram positive cocci. Cells in pairs.

Requires blood or serum for growth. α-haemolytic activity on blood
agar (green colour)

Polysaccahride capusle: 95 capsular types

Question 15

What is the normal habitat of S. pneumoniae?

Answer 15

Human respiratory tract - droplet spread

Question 16

What treatment is given for S.pneumoniae meningitis?

Answer 16

Ceftriaxone, cefotaxime

Penicillin resistant common in some parts of the world

Question 17

In what group of patients with meningitis should steroids be given?

Answer 17

If S. pneumonia is suspected

Question 18

Which organisms cause neonatal meningitis?

Answer 18

Group B beta-haemolytic Streptococci

Escherichia coli

Listeria monocytogenes

Question 19

What are the clinical features of neonatal meningitis?

Answer 19

Neonatal infection. Variable onset

Early ( 5 days). Usually meningitis.

Question 20

What treatment is given for neonatal meningitis?

Answer 20

Cefotaxime

Ampicillin and gentamicin

Question 21

What are the complications of meningitis?

Answer 21

• Death
• Overwhelming sepsis
• Raised intracranial pressure
• Deafness
• Delayed development
• Seizures
• Stroke
• Hydrocephalus

Question 22

What are the common causes of lymphocytic meningitis?

Answer 22

Virus (HSV etc)
TB
Spirochetes

Question 23

What are the features of TB meningitis?

Answer 23

Important differential

Insidious onset

Epidemiological risk factor for TB:

• Immunocompromised
• Alcoholic
• Travel

Diagnosis difficult

• AFB often not seen on microscopy
• Delay in diagnosis leads to a worse prognosis

12 months standard TB treatment
Steroids beneficial

Question 24

What are the features of cryptococcal meningitis?

Answer 24

Cryptococcus is a yeast

Common problem in patients with late stage HIV

Insidious onset

Lymphocytic meningitis

Yeast forms seen in CSF in Indian Ink stain

Question 25

What treatment is given for cryptococcal meningitis?

Answer 25

Prolonged course of treatment with:

- amphotericin, flucytosine or fluconazole

Question 26

What are the features of Clostridium tetani?

Answer 26

Gram positive spore forming bacillus

Terminal round spore (drumstick)

Strict anaerobe

Question 27

How does C. tetani produce disease?

Answer 27

• Toxin genes plasmid encoded
• Toxin spreads via bloodstream and retrograde transport
• Binds to ganglioside receptors and blocks release of inhibitory interneurones
• Convulsive contraction of voluntary muscles

Question 28

What are the clinical features of tetanus?

Answer 28

Tonic muscle spasms

Trismus

Opisthotonus

Respiratory difficulties

Cardiovascular instability
(sympathetic nervous system)

Question 29

What treatment is given for tetanus?

Answer 29

Antitoxin (horse or human)

Penicillin or metronidazole

Drugs for spasms

Muscle relaxants

Respiratory support

Question 30

Is encephalitis usually bacterial or viral in origin?

Answer 30

Viral