Bacterial and fungal meningitis Flashcards Preview

Clinical Pathology > Bacterial and fungal meningitis > Flashcards

Flashcards in Bacterial and fungal meningitis Deck (30):
1

What are the features of Neisseria meningitidis?

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)

2

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

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

3

What is the natural habitat of N. meningitidis?

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

4

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

Presence of capsule
Acquisition of iron from ferritin

5

What are the possible presentations of N. meningitidis infection?

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

6

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

Ceftriaxone, cefotaxime
Penicillin
Intensive care management

7

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

Rifampicin
Ciprofloxacin

8

What are the features of Haemophilus influenzae?

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

9

What is the normal carriage of H. influenzae?

Restricted to humans

25-80% carry non-capsulate strains

5-10% carry capsulate strains

Nasopharynx

10

How does H. influenzae reach the bloodstream?

Throat carriage – invasion of submucosa – blood stream

11

What are the H. influenzae virulence factors?

Type b capsule

Fimbriae

IgA proteases

Outer membrane proteins/lipolysaccharide

12

What treatment is given for H. influenzae?

Ceftriaxone, cefotaxime

Ampicillin

β-lactamase producing strains common

13

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

Rifampicin

14

What are the features of Streptococcus pneumoniae?

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

15

What is the normal habitat of S. pneumoniae?

Human respiratory tract - droplet spread

16

What treatment is given for S.pneumoniae meningitis?

Ceftriaxone, cefotaxime

Penicillin resistant common in some parts of the world

17

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

If S. pneumonia is suspected

18

Which organisms cause neonatal meningitis?

Group B beta-haemolytic Streptococci

Escherichia coli

Listeria monocytogenes

19

What are the clinical features of neonatal meningitis?

Neonatal infection. Variable onset

Early ( 5 days). Usually meningitis.

20

What treatment is given for neonatal meningitis?

Cefotaxime

Ampicillin and gentamicin

21

What are the complications of meningitis?

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

22

What are the common causes of lymphocytic meningitis?

Virus (HSV etc)
TB
Spirochetes

23

What are the features of TB meningitis?

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

24

What are the features of cryptococcal meningitis?

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

25

What treatment is given for cryptococcal meningitis?

Prolonged course of treatment with:
- amphotericin, flucytosine or fluconazole

26

What are the features of Clostridium tetani?

Gram positive spore forming bacillus

Terminal round spore (drumstick)

Strict anaerobe

27

How does C. tetani produce disease?

- 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

28

What are the clinical features of tetanus?

Tonic muscle spasms

Trismus

Opisthotonus

Respiratory difficulties

Cardiovascular instability
(sympathetic nervous system)

29

What treatment is given for tetanus?

Antitoxin (horse or human)

Penicillin or metronidazole

Drugs for spasms

Muscle relaxants

Respiratory support

30

Is encephalitis usually bacterial or viral in origin?

Viral

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