Central Nervous System Infections Lecture

Question 1

Viral meningitis - time of year, viruses, diagnosis, treatment

Answer 1

COMMON
Late summer/autumn
Viruses - Enteroviruses eg ECHO or other microbes and non infectious causes
Diagnosis - viral stool culture, throat swab and CSF PCR
Treatment - supportive as self limiting

Question 2

Viral encephalitis - viruses

Answer 2

Herpes simplex - diagnose QUICKLY

Question 3

Is Viral Encephalitis travel or occupational related?

Answer 3

Yes.
Travel - West Nile, Japanese B encephalitis, Tick Borne Encephalitis
Occupation - Rabies

Question 4

Clinical Features Encephalitis (6)

Answer 4

Insidious onset - sometimes sudden
Meningismus
Stupor, coma
Seizures, partial paralysis
Confusion, psychosis
Speech, memory problems

Question 5

Investigations for Encephalitis (3)

Answer 5

LP
EEG
MRI
if delay start pre-emptive aciclovir as prompt therapy improves outcomes

Question 6

Describe MRI findings in Encephalitis

Answer 6

Inflamed portion of the brain brightest white. Usually temporal lobe

Question 7

Common causes of bacterial meningitis in..
Neonates
Children
10 to 21
21 onward
Elderly

Answer 7

Neonates - listeria, group b strep, e.coli
Children - h.influenze
10 to 21 - meningococcal
21 onward - pneumococcal>meningococcal
Elderly - pneumococcal > listeria

Question 8

Common causes of bacterial meningitis with these risk factors...
Decreased CMI
S/P neurosurgery or opened head trauma
Fracture of the cribiform plate
Immunocompromised

Answer 8

Decreased CMI - listeria
S/P neurosurgery or opened head trauma - staphylococcus, gram negative rods
Fracture of the cribiform plate - pneumococcal
Immunocompromised - s.pneumonia, n.meningitidis, listeria

Question 9

Bacterial Meningitis - Clinical Signs (3)

Answer 9

Fever
Stiff neck
Alteration in consciousness

Question 10

Bacterial Meningitis - Signs and Symptoms (8)

Answer 10

Headache
Vomiting
Pyrexia
Neck stiffness
Photophobia
Lethargy
Confusion
Rash

Question 11

Signs of bacterial meningitis often absent or atypical in..? (3)

Answer 11

The very young
The very old
Immunocompromised people

Question 12

In bacterial meningitis which kind of WBC would you expect to find in the subarachnoid fluid?

Answer 12

Neutrophils

Question 13

Describe some potential pathogenesises of bacterial meningitis (3)

Answer 13

1. Nasopharyngeal colonisation
2. Direct extension of bacteria
   - parameningeal foci (sinusitis, brain abscess, mastoiditis)
   - across skull defects/fracture
3. From remote foci of infection eg endocarditis, pneumonia, UTI

Question 14

Antibiotic of choice for listeria monocytogenes

Answer 14

IV Ampicillin/amoxicillin

Gram positive bacilli

Intrinsically resistant to ceftriaxone

Question 15

Which subgroup of patients do we mainly see crytococcal meningitis in?

Answer 15

HIV patients

Question 16

When we send CSF for interpretation what do we want to know from…

1. Haematology
2. Microbiology
3. Chemistry

Answer 16

1. cell count, differential
2. gram stain, cultures
3. glucose, protein

Question 17

What is the typical cell type CSF findings in Viral meningitis

Answer 17

cells are lymphocytes

Question 18

What are the CSF findings for bacterial meningitis

1. Cell type
2. Protein levels
3. Glucose levels

Answer 18

1. predominantly polymorphs
2. protein high
3. glucose less than 70% of blood glucose

Question 19

What is the CSF findings for partially treated bacterial meningitis

1. Cell type
2. Protein levels
3. Glucose levels

Answer 19

1. predominantly lymphocytes
2. protein high or very high
3. glucose normal or decreased

Question 20

CSF predictive of bacterial meningitis with 99% accuracy if….

Answer 20

WBC count >2000
Neutrophils >1180
Protein >220mg/dl
Glucose

Question 21

What is aseptic meningitis?

Answer 21

Non pyogenic bacterial meningitis

Question 22

What spinal fluid formula does aseptic meningitis typically have?

Answer 22

Low WBC
Minimally elevated protein
Normal glucose

Question 23

Infectious and treatable causes of aseptic meningitis/encephalitis syndrome (9)

Answer 23

HSV 1 and 2
Syphilis
Listeria (occasionally)
Tuberculosis
Cryptococcus
Leptospirosis
Cerebral malaria
African tick typhus
Lyme disease

Question 24

Non-infectious and treatable causes of aseptic meningitis/encephalitis syndrome (6)

Answer 24

Carcinomatous
Sarcoidosis
Vasculitis
Dural venous sinus thrombosis
Migraine
Drug
Co-trimoxazole
IVIG
NSAIDS

Question 25

Indications for hospital admission in acute adult bacterial meningitis (5)

Answer 25

- signs of meningeal irritation
 - an impaired conscious level
 - a petechial rash
 - who are febrile or unwell and have had a recent fit
 - Any illness, especially headache, and are close contacts of patients with meningococcal infection, even if they have received a prophylactic antibiotic

Question 26

Early inpatient action for acute adult bacterial meningitis (4)

Answer 26

- take blood for culture and coagulation screen 
- give the empirical treatment - LP 
- take a throat swab which should be plated as soon as practicable by the microbiologist 
- disrupt and swab or aspirate any petechial or purpuric skin lesions for microscopy and culture

Question 27

What should be done to investigate patients with papilloedema or focal neurological signs?

Answer 27

Urgent CT or nuclear magnetic resonance scan | BUT DONT delay appropriate antibiotics

Question 28

Who should undergo CT before Lumbar Punctures? (6)

Answer 28

``` Immunocompromised patients History of CNS disease New onset seizure Papilloedema Abnormal level of consciousness Focal neurologic deficit ```

Question 29

Indications for lumbar puncture in acute adult bacterial meningitis

Answer 29

All adult patients with suspected meningitis except when a clear contraindication exists (III) or of there is a confident clinical diagnosis of meningococcal infection with a typical meningococcal rash (III)

Question 30

Should antibiotics be given before or after lumbar puncture in acute bacterial meningitis?

Answer 30

BEFORE

Question 31

Should you give steroids if you are not confident you are using the correct antimicrobials?

Answer 31

NO

Question 32

What is the empiric antibiotic therapy for acute adult bacterial meningitis?

Answer 32

EMPIRIC ANTIBIOTIC THERAPY IV CEFTRIAXONE 2g bd ADD IV AMPICILLIN/AMOXICILLIN 2g qds IF LISTERIA SUSPECTED

Question 33

What is the empiric antibiotic therapy for acute adult bacterial meningitis IF penicillin allergy?

Answer 33

PENICILLIN ALLERGY (RASH OR ANAPHYLAXIS) If there is a clear history of anaphylaxis to beta-lactams give chloramphenicol iv 25 mg/kg 6-hourly with vancomycin iv 500 mg 6-hourly or 1g 12-hourly. If listeria suspected and penicillin allergy co-trimoxazole alone has been used successfully for this infection.

Question 34

When do we give steroids to patients suspected of bacterial meningitis?

Answer 34

Give to all patients suspected of bacterial meningitis (10mg iv 15-20 min before or with the first dose of antibiotic and then every 6 hours for 4d) Unfavourable outcome reduced from 25% to 15% and mortality from 15 to 7% Most striking benefit in pneumococcal meningitis Less likely also to have impaired consciousness,seizures and cardio-respiratory failure Do not give in post-surgical meningitis, severe immunocompromise, meningococcal or septic shock or those hypersensitive to sterroids