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infec y3s1 > IC17 Community acquired bacterial meningitis > Flashcards

IC17 Community acquired bacterial meningitis Flashcards

1
Q

risk factors/ predisposing factors

TIC2S

A
  1. immunocompromised
  2. prolonged contact with infected individuals
  3. travel to endemic areas
  4. CNS shunting: tube draining CSF from brain due to fluid buildup
  5. splenectomised patients
    * Removal of spleen due to its enlargement will compromise immunity ⇒ important to be vaccinated to prevent bacterial infections
    * Spleen = important for immunity against bacterial infection; have macrophages that neutralise bacteria
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2
Q

mechanisms of entry

A

Invasion of mucosal surface
* Bacteria transported in blood to meninges

Spread from para-meningeal focus
* Organs nearby affected organ can get infected by bacteria
* Local infections → sinusitis, otitis media, pharyngitis

Head trauma
* Direct inoculation of bacteria onto meninges from external due to opening of meninges

Anatomical defects
* Bacteria can colonise & invade; Multiplication of bacteria ⇒ infection
* CSF fistula/ leak
Fistula → abnormal connection between tissues
Leak → break in mucosa (supposedly closed)
* Congenital defects → structural damage protecting tissues; allows spread of bacteria

Neurological procedures
Bacteria introduced during surgery

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3
Q

symptoms

A
  • Fever, chills
  • Classic triad: headache, backache, nuchal (neck) rigidity
  • Mental status change (irritability), photophobia
  • N/V, anorexia, poor feeding habits (infants)
  • petechiae/ purpura ⇒ neisseria meningitidis meningitis infection
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4
Q

physical signs

A

Kernig sign
When hamstring extended & thigh is perpendicular to trunk ⇒ severe back pain

Brudzinski sign
* Severe neck stiffness
* When neck held up, hip & knee will naturally move up

Building fontane
* Occurs in children
* Skull does not close up due to inflammation (alot of CSF & inflammatory processes)

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5
Q

diagnostic methods

A
  1. hx & physical examination
  2. blood culture
  3. lumbar puncture
  4. general lab tests
  5. radiology (brain CT scan/ MRI)
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6
Q

diagnostic: lumbar puncture

what can be derived, continuation of empiric therapy

A

CSF composition, gram-stain, culture & PCR (to check for genetic material)
Suggestive, but do not confirm aetiology of meningitis

To continue empiric therapy until CSF culture becomes negative + no other evidence of bacterial infection

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7
Q

p

diagnostic: lumbar puncture
composition of normal CSF

glucose, protein, WBC

A

Glucose
2.6-4.5 mmol/L
CSF : blood > 0.66

Protein
< 0.4 g/L

WBC
< 5 cells/ mm3

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8
Q

diagnostic: lumbar puncture
composition of bacterial meningitis

glucose, protein, WBC

A

Glucose
Very low
CSF : blood < 0.4 (Due to bacteria consuming glucose)

Protein
Raised; >1.5 g/L

WBC
Raised; > 100 cells/ mm3
Predominantly neutrophils; for pleocytosis

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9
Q

diagnostic: lumbar puncture
composition of viral meningitis

glucose, protein, WBC

A

Glucose
Normal to slightly low

Protein
Normal to mildly raised

WBC
Raised; 5-1000 cells/ mm3
Predominantly lymphocytes; to clear virus

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10
Q

diagnostic: general lab test

Examples

A

WBC, C-reactive protein, procalcitonin

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11
Q

diagnostic: radiology

indications, when to conduct

A

Usually for:
* Evaluation of differential diagnosis & complications
* If patient conscious level is low/ not alert

Can be done before lumbar punctures in patients with concerns of brain shift due to mass lesion (extremely swollen brain)
* Due to risk of brain herniation (dropping of tissues) during lumbar puncture

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12
Q

causative pathogens: neonates (<1 month)

A

Group B streptococcus (streptococcus agalactiae)
E.coli
Listeria monocytogenes

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13
Q

causative pathogens: infants-children (1-23 months)

A

Streptococcus pneumoniae
Neisseria meningitidis
Group B Streptococcus (S. agalactiae)
E.coli

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14
Q

causative pathogens: children-adults (2-50 years)

A

S.pneumoniae
N. meningitidis

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15
Q

causative pathogens: adults (>50 years)

A

S.pneumoniae
N. meningitidis
L. monocytogenes
Aerobic gram-negative bacilli: E.coli, Klebsiella species

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16
Q

causative pathogens: Listeria Monocytogenes

characteristics, common infectees, where it is found

A
  • Gram-positive, intracellular rod bacteria
  • Commonly infected elderly & young ⇒ weaker immune system; unable to clear bacteria
  • Found in moist environment, soil & water
  • Linked to food-borne disease outbreaks
    ie: cold deli meats & unpasteurised dairy products
  • Can grow & replicate in refrigerator temperature
17
Q

causative pathogen: Neisseria meningitidis

characteristics, location

A
  • Fastidious, encapsulated, aerobic gram-negative diplococcus
  • Exists in nasopharynx of healthy individuals
18
Q

empiric therapy: when to start

A

ASAP, within 1 hour

19
Q

empiric therapy: neonates

A

Ceftriaxone + ampicillin

20
Q

empiric therapy: infants-children

A

Ceftriaxone + vancomycin

21
Q

empiric therapy: children-adult

A

Ceftriaxone + vancomycin

22
Q

empiric therapy: >50 year old

A

Ceftriaxone + vancomycin + ampicillin

23
Q

culture-directed therapy: ROA

A

All IV treatment → to ensure high serum concentration of drug enters CSF

24
Q

culture-directed therapy: s. pneumoniae

drugs & duration

A

10-14 days

Penicillin susceptible: Penicillin G or Ampicillin

Penicillin resistant, cephalosporin susceptible:
Ceftriaxone

Penicillin & cephalosporin resistant:
Vancomycin + rifampicin

25
Q

culture-directed therapy: listeria monocytogenes

drugs & duration

A

≥ 21 days

Penicillin susceptible: Penicillin G or Ampicillin

Penicillin allergy: co-trimoxazole, meropenem

26
Q

culture-directed therapy: Neisseria Meningitidis

drugs & duration

A

5-7 days

Penicillin susceptible: Penicillin G or Ampicillin

Penicillin resistant, cephalosporin susceptible:
Ceftriaxone

27
Q

culture-directed therapy: grp B strep

drugs & duration

A

14-21 days

Penicillin susceptible: Penicillin G or Ampicillin

Penicillin resistant, cephalosporin susceptible:
Ceftriaxone

28
Q

adjunctive therapy: dexamethasone

indication

A

Recommended for patients with bacterial meningitis > 6 weeks old (beyond neonatal age)
Due to severe inflammation of subarachnoid space
Key bacteria for initiation: H.influenzae & S.pneumoniae

29
Q

adjunctive therapy: dexamethasone

A

Recommended for patients with bacterial meningitis > 6 weeks old (beyond neonatal age)
Due to severe inflammation of subarachnoid space
Key bacteria for initiation: H.influenzae & S.pneumoniae

30
Q

adjunctive therapy: dexamethasone

benefits

A
  • Less hearing loss & other neurologic sequelae in H.influenzae & S.pneumoniae meningitis
  • Decreased mortality in S.pneumoniae meningitis
31
Q

adjunctive therapy: dexamethasone

risks

A

May decrease AB penetration
* Meningitis = inflammation of meninges; allows for more AB to enter
* Reduction of inflammation ⇒ lesser drugs can enter

ADR: mental status changes (ie: delirium), hyperglycemia, hypertension

32
Q

adjunctive therapy: dexamethasone

dosing instructions

A

Administer 10-20 mins before OR at same time as first dose of AB
* AB kills bacteria; releases substances that can cause more significant inflammation
* Dexamethasone ⇒ prophylaxis to control inflammation

Dexamethasone 10 mg q6h up to 4 days [adult dose]

Stop if patient discovered not to have bacterial meningitis OR if bacterium causing meningitis is not H.influenzae or S.pneumoniae

33
Q

AB dosing

ampicillin, penG, ceftriaxone, vanco, rifampicin, meropenem

A
  1. IV 2g q4h
  2. IV 4MU q4h
  3. IV 2g q12h
  4. IV 25-30mg/kg q8-12h
  5. IV 300mg q12h
  6. IV 2g q8h
34
Q

AB to caution/ avoid

A
  • Imipenem & fluoroquinolones at high doses ⇒ may cause seizures
  • cefepime in patients on dialysis → must properly adjust for renal dosing
    No proper adjustments ⇒ may cause accumulation in blood & seizures
  • All b-lactam at supratherapeutic levels ⇒ may be neurotoxic
35
Q

prophylaxis for meningococcal meningitis
indication

key bacteria, individuals

A

Key bacteria: Neisseria meningiditis

close contacts & exposure to oral secretions of infected individuals

36
Q

prophylaxis for meningococcal meningitis
drug choice

A

Rifampicin ⇒ total 2 days therapy
* Adults: 600 mg q12h, 4 doses
* Children: 10 mg/kg q12h, 4 doses
* Infants (<1 month): 5 mg/kg q12h, 4 doses

Ciprofloxacin: PO 500 mg, 1 dose ⇒ only for adults
Not for children due to arthropathy risk

Ceftriaxone: IM 125-250 mg, 1 dose

infec y3s1 (7 decks)

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