IC17: Bacterial Meningitis

Question 1

Which of the following is considered septic meningitis? Select all that apply

a) Bacteria

b) Virus (e.g enterovirus, herpes)

c) Fungal (e.g. cryptococci), parasitic (e.g. malaria), mycobacterium (e.g. TB), syphilis

d) Drugs

e) Autoimmune diseases

Answer 1

A only (bacterial causes)

Question 2

What are the classic triad of symptoms for BM?

Answer 2

Headache, backache, nuchal (neck) rigidity

Question 3

What symptom is a key clue for BM caused by Neisseria Meningitidis?

Answer 3

Petechiae or purpura on skin

Question 4

State the various ways lumbar puncture helps in diagnosis and management of BM

Answer 4

1) Elevated opening pressure (diagnosis)

2) CSF composition analysis (differentiate bacterial from viral)

3) CSF gram stain and culture (get AST)

4) CSF PCR (diagnose viral meningitis/ identification of organism)

Question 5

State the various ways CSF composition will differ in a patient with BM compared with healthy individual

Answer 5

BM patient:
1) Cloudy CSF appearance

2) Lower CSF: blood glucose ratio (<0.4)

3) Increased protein level (>1.5g/L)

4) Neutrophilic Pleocytosis (>100 cells/mm^3, white cells predominantly neutrophils)

Question 6

In which groups of patients will Listeria Monocytogenes be more likely to be isolated?

Answer 6

Neonates (<1 month old)

Adults (>50 year old)

Question 7

In what age group will there be a concern of Group B streptococcus BM?

Answer 7

< 2 years old

Question 8

What is the most common pathogen that causes BM?

Answer 8

S. pneumoniae

Question 9

What are the bacteria commonly present in the nasopharynx that can cause BM?

Answer 9

S. pnemoniae and Neisseira Meningitidis

Question 10

State the pathogens to be targeted empirically for the various age groups.

Answer 10

Neonates (< 1mth old):
- Grp B Strep
- Listeria
- E. coli

Infants (< 2 y.o):
- Grp B strep
- E. coli
- S. pneumoniae
- Neisseria Meningitidis

Children > 2 y.o and adults:
- S. pneumoniae
- Neisseria Meningitidis

Adults > 50 y.o:
- S. pneumoniae
- Neisseria Meningitidis
- Listeria
- Aerobic gram-negative bacilli (e.g E coli, Klebsiella)

Question 11

State the empiric antibiotic regimen used for each age group and state the purpose of adding/removing certain antibiotics depending on the age group

Answer 11

Neonate: Ceftriaxone + Ampicillin (Ampicillin to cover Listeria)

Infant (>1 mth) -adult (< 50 y.o): Ceftriaxone + Vancomycin (Vanco covers potential penicilin and cephalosporin resistant S. Pneumoniae)

Adult > 50 y.o: Ceftriaxone + Vancomycin + Ampicillin

Question 12

State the culture directed therapy for BM as well as duration of therapy for both positive and negative culture

Answer 12

1) Group B streptococcus:
- Penicillin G or
- Ampicillin or
- Ceftriaxone (mild penicilin allergy) Duration: 14-21 days

2) Streptococcus pneumoniae
- Penicillin G or Ampicillin (if penicillin susceptible)
- Penicillin resistant, cephalosporin susceptible: Ceftriaxone
- Penicillin, cephalosporin resistant: vancomycin plus rifampicin
Duration: 10-14 days

3) Neisseria meningitidis
- Penicillin susceptible: Penicillin or Ampicillin
- Penicillin resistant or mild allergy (mild rash): Ceftriaxone
Duration: 5-7 days

4) Listeria monocytogenes
- Penicillin G or Ampicillin
- Penicillin allergy: Co-trimoxazole, meropenem
Duration: ≥ 21 days

5) Negative culture, treat with empiric antibiotics, duration: at least 14 days

Question 13

When is adjunctive corticosteroid recommended in BM? State the adult dose

Answer 13

Recommended in patients with bacterial meningitis caused by S. pneumoniae or H. influenzae beyond the neonatal age (from 6 weeks upwards).

10mg q6h up to 4 days

Question 14

State the benefits of adjunct Corticosteroid in BM when used in appropriate group of patients

Answer 14

Decreased neurologic sequalae and hearing loss for pts with S. pneumo and H. influenzae

Decreased mortality for S. pneumo pts

Question 15

State who would need chemoprophylaxis for BM

Answer 15

For close contacts (household or day care) and those exposed to oral secretions of index case of Neisseria Meningitidis

Question 16

State the antibiotics regimen that can be used for chemoprophylaxis of N. Meningitidis Meningitis.

Answer 16

1) Rifampicin
Adult: 600mg q12h, 4 doses (based on child dose, adult ~60kg)
Child: 10mg/kg q12h, 4 doses
Infant (< 1 month old): 5mg/kg q12h, 4 doses

2) Ciprofloxacin
PO 500mg, single dose (for adult only)

3) Ceftriaxone
125-250mg IM, single dose

Question 17

Explain the pathophysiology of BM

Answer 17

Exposure to predisposing factors that increase risk of colonisation and infection by bacteria that can cause BM -> bacteria gain entry into body via various means and in susceptible host, enter the meninges

Question 18

What are the risk factors for BM

Answer 18

1) Defects in the head (surgery, unfused fontanel, head trauma, CNS shunt, CSF fistula/leak)

2) Metastasis of other infections from parameningeal focus (e.g otitis media, pharyngitis and sinusitis)

3) Immunosuppressed (HIV, functional or anatomical Asplenia, corticosteroid use etc.)

4) Male

5) Travel to endemic countries (e.g low income country)

6) Close contact with infected

7) Young age

Question 19

State the difference in CSF composition between viral and bacterial meningitis

Answer 19

Appearance: BM CSF turbid, VM CSF is clear

CSF glucose: blood glucose ratio:
both lowered but BM lower than VM

Protein: BM significantly higher than VM

White level: both raised; VM (5-1000 cells/mm^3). White cell predominant for VM is lymphocyte (Lymphocytic Pleocytosis) vs Neutrophilic pleocytosis in BM

Question 20

When is brain imaging done in BM?

Answer 20

o Not required for diagnosis of meningitis, but usually done to evaluate for differential diagnosis and complications

o May be done prior to lumbar puncture in patients with concern for brain shift due to a mass lesion, due to risk of brain herniation during lumbar puncture in these patients (usually for severe meningitis)

Question 21

Patient X developed BM and was suitably treated with empiric therapy. Culture today returned showing isolates significant for a Gram-positive intracellular rod. State the bacteria causing the BM and how should his BM treatment be modified.

Answer 21

Pathogen: Listeria monocytogenes

Culture directed therapy
Ampicillin or Pen G

If penicillin allergy: Bactrim or Meropenem

Treatment duration > 21 days

Question 22

Patient X developed BM and was suitably treated with empiric therapy. Culture today returned showing isolates significant for an aerobic Gram-negative diplococcus. State the bacteria causing the BM and how should his BM treatment be modified.

Answer 22

Pathogen:
Neisseria Meningitidis

Treatment:
Pen G or Ampicillin

If mild allergy or penicillin resistance: Ceftriaxone

Duration: 5-7 days