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PR3151 Finals > IC17 CA- bacterial meningitits and C.difficile > Flashcards

IC17 CA- bacterial meningitits and C.difficile Flashcards

1
Q

define meningitis

A

inflammation of the leptomeninges

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2
Q

parts of leptomeninges

A
  • arachnoid
  • subarachnoid space (cerebrospinal fluid)
  • pia mater
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3
Q

causes of meningitis

A
  • infection (bacteria/septic meningitis, virus, fungal, parasitic, syphilis)
  • drugs (bactrim, ibuprofen)
  • autoimmune diseases
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4
Q

incidence of bacteria meningitis

A
  • more in africa population
  • male > female
  • common in children
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5
Q

RF bacteria meningitis

A
  • immune deficiency (CS, HIV)
  • prolonged close contact with infected pt
  • travel to endemic areas
  • head trauma
  • CNS shunts
  • neurologic pts
  • CSF fistula/leak
  • local infection (sinusitis, otitis media, pharyngitis)
  • splenectomised pt
  • congenital defects
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6
Q

how does bacteria gain entry into the body for meningitis

A
  1. invasion of mucosal surface -> hematogenous spread to brain
  2. spread from para-meningeal focus (otits media, sinusistis)
  3. penetrating head truama
  4. anatomical defects in meninges
  5. previous neurological procedures
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7
Q

symptoms of bacterial meningitis

A
  • fever, chills
  • classic triad (headache, neck rigidity, backache)
  • mental status changes (irritability)
  • photophobia
  • N/V, anorexia, poor feeding habits (infants)
  • Petechiae, purpura (wide and large red spots) -> from neisseria meningitidis meningitis
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8
Q

physical signs of bacterial meningitis

A
  • Kernig sign (back pain when leg raised)
  • Brudzinski sign (neck raised, leg bent)
  • Bulging fontane (usually in babies)
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9
Q

diagnosis of bacterial meningitis

A
  1. history and physical examination
  2. blood cultures
  3. lumbar puncture
    - elevated opening pressure
    - CSF composition
    - CSF gram-stain and culture
    - CSF PCR
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10
Q

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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11
Q

bacterial meningitis CSF
- glucose
- protein
- WBC

A

glucose: very low
CSF : blood > 0.4

protein: >1.5 g/L
WBC: >100 cells/mm3 (mostly neutrophils) -> pleocytosis

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12
Q

viral meningitis CSF
- glucose
- protein
- WBC

A

glucose: normal to slightly low
protein: normal to slightly raised
WBC: 5-1000 cells/mm3 (mostly lymphocytes)

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13
Q

lab findings for bacterial meningitis

A

general lab findings (WBC, CRP, procalcitonin)
- signs of systemic infection
- non specific for bacterial meningitis

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14
Q

radiology- brain imaging (CT/MRI) for meningitis

A
  • not required for diagnosis (usually only for differential diagnosis)
  • MAY BE DONE prior to lumbar puncture (prevent risk of brain herniation)
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15
Q

meningitis: when should abx be started?

A

Antibiotic should be started as soon as possible (within 1 hour)

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16
Q

bacterial meningitis likely organism in neonates (<1yo) and abx used

A
  • Grp B streptococcus (strep agalactiae)
  • E.coli
  • Listeria monocytogenes
  • IV ceftriaxone + ampicillin (for Listeria)
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17
Q

bacterial meningitis likely organism in infants and children (1-23 mths) and abx used

A
  • Streptococcus pneumoniae
  • Neisseria meningitidis
  • Strep agalactiae
  • E.coli
  • IV ceftiaxone + vancomycin (vanco to cover resistant strep pneumoniae)
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18
Q

bacterial meningitis likely organism children and adults (2-50 yo) and abx used

A
  • Strep pneumoniae
  • Neisseria meningitidis
  • IV ceftriaxone + vancomycin
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19
Q

bacterial meningitis likely organism adults (>50 yo) and abx used

A
  • Strep pneumoniae
  • Neisseria meningitidis
  • Listeria monocytogenes
  • gram negative bacilli (E.coli, Klebs)
  • IV ceftriaxone + vancomycin + ampicillin
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20
Q

culture directed for Strep pneumoniae

A

(pen susceptible) IV pen G, ampicillin
(pen resistant, cephalosporin susceptible) ceftriaxone
(pen, ceph resistant) vancomycin + rifampicin

duration: 10-14 days

IV rifampicin 300mg q12h

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21
Q

culture directed for Neisseria meningitidis

A

(pen susceptible) IV pen G, ampicillin
(pen resistant, mild allergy) ceftriaxone

duration: 5-7 days

22
Q

culture directed Listeria monocytogenes

A

(pen susceptible) IV pen G, ampicillin
(pen allergy) co-trimoxazole, meropenem

duration >21days

23
Q

culture directed Grp B strep (strep agalactiae)

A

(pen susceptible) IV pen G, ampicillin
(pen resistant, mild allergy) ceftriaxone

duration: 14-21 days

24
Q

if culture negative how? (Meningitis)

A

empiric abx for at least 14 days (may be extended)

25
Q

bacterial meningitis - adjunctive corticosteroids

A

dexamethasone 10mg q6h (up to 4 days)

For: > 6weeks (more than neonatal age)
administer 10-20mins before or tgt with first dose abx
stop when bacterial not (S.pneumoniae or H.influenzae)

Benefits:
- less hearing loss and neurologic sequelae (in H.influenzae and S.pneumoniae)
- decreased mortality (in S.pneumoniae)

Risks:
- decrease abx penetration
- ADR - mental status changes, hyperglycemia, HTN

26
Q

bacterial meningitis - therapeutic response

A
  • most pt improve within 48hrs
  • if never improve -> brain imaging is indicated to detect cerebrovascular complications (stroke, brain abscess)
  • if improve: no need repeat microbiological test
  • ADR
  • morbidity is common in bacterial meningitis
27
Q

abx use in meningitis must:

A
  1. distribute to CSF (achieve adequate CSF concentrations) - usually high dose, IV
  2. active against likely pathogens
  3. does not aggravate CNS morbidity (eg seizures)
    - imipenem and cefepime increase risk of seizures
28
Q

meningitis: RF for close contact

A

exposure to oral secretions of pt with bacterial meningitidis

29
Q

chemoprophylaxis for close contact for meningitis

A
  1. rifampicin PO
    (adults) 600mg q12hr x4 doses
    (children) 10mg/kd q12hrs x4 doses
    (infants <1mth) 5mg/kg q12hrs x4 doses
  2. ciprofloxacin 500mg PO x1 dose
  3. ceftriaxone 125-250mg IM x1 dose
30
Q

what kind of bacteria is Clostridoides difficile?
- what are the toxins strains produced
- how are spores transmitted?

A

gram positive, spore forming anaerobic bacillus
- produces toxin A and B
- transmitted by fecal-oral route

31
Q

can C.difficle be asymptomatic?

A

yes
asymptomatic carriage to fulminant disease

32
Q

describe pathogenesis of C.difficile

A
  • colonisation of intestinal C.difficle occurs via fecal-oral route
  • facilitated by abx use
  • toxigenic C.difficile release 2 toxins (toxin B more clinically important than toxin A)
  • toxin leads to inflammation and diarrhoea
33
Q

why are some people asymptomatic carriers

A

they have antibodies to the toxins (more than normal)

34
Q

C.difficile: RF

A
  • advanced >65 yo
  • multiple/ severe comorbidities
  • immunosuppression
  • hx of CDI (more vulnerable)
  • GI surgery
  • tube feeding
  • prior hospitalisation (in last 1 year)
  • duration of hospitalisation
  • residence in nursing home or long term care facilities
  • use of abx
  • use of gastric acid suppressive tx (PPI)
35
Q

which abx has increased risk of developing CDI

A

all abx
greatest risk:
- clindamycin
- 3rd/4th gen cephalosporins
- fluroquinolones

highest risk while receiving abx, elevated up to 12 weeks later

36
Q

which abx has protective effect against developing CDI

A

doxycycline
tigecycline
- inhibits toxin production
- minimal effects on gut flora

37
Q

CDI infection control and prevention

A
  1. isolation
  2. hand hygiene
  3. environmental cleaning
  4. antimicrobial stewardship
38
Q

CDI: Recognise the critical role of Antimicrobial Stewardship in reducing incidence of CDI

A

protective effect with reduce use abx
other modalities to reduce Cdiff
- acid suppression (reduce unnecessary PPI)
- probiotics (to reestablish microbiota)

39
Q

Clinical presentations of C.difficile
(mild, moderate, severe)

A
  • watery diarrhoea (>= 3 loose stools in 24hrs)

(mild)
- diarrhoea, abdominal cramps
(morderate)
- fever, diarrhoea, nausea malaise
- abdominal cramps and distension
- leukocytosis
- hypovolemia (due to dehydration)
(severe)
- fever, diarrhoea, diffused abdominal crmaps and distension
- WBC >= 15 x 10^9
- SCr >= 133 umol/L

(fulminant) - severe and sudden
- hypotension/shock, ileus, megacolon (no peristalsis, colon is swollen)

40
Q

dx of C.difficile

A
  • presence of diarrhea (3 unformed stools in 24 hours), or
  • radiographic evidence of ileus or toxic megacolon
    AND
  • A positive stool test result for C difficile or its toxins, or
  • Colonoscopic or histopathologic evidence of
    pseudomembranous colitis
41
Q

which grp of patients should CDI testing be done in?

A

symptomatic pt only
lab stool test cannot differentiate btw colonisation and infection

42
Q

things to note before doing stool test for C.difficile

A
  • do not test for asymptomatic pt
  • only test when pt has diarrhoea (>= 3 unformed stools per day)
  • pt not using laxatives within past 48hrs
  • do not repeat in <7 days
  • do not repeat to document cure
43
Q

management of C.difficile (tx principles)

A
  • do not treat asymptomatic patients (confirm CDI presence)
  • discontinue any abx therapy not treating CDI (if possible)
  • select narrowest agent
  • avoid agents with strong association with CDI
44
Q

define non severe C.difficile and abx used

A

WBC < 15 x 10^9 L AND
SCr < 133 umol/L

PO Fidaxomicin 200mg BD
PO Vancomycin 125mg QDS
(alternative)
PO metronidazole 400mg TDS

10 days (14 days if sx not completely resolved)

45
Q

define severe C.difficile and abx used

A

WBC >= 15 x 10^9 OR
SCr >= 133 umol/L

PO Fidaxomicin 200mg BD
PO Vancomycin 125mg QDS

10 days (14 days if sx not completely resolved)

46
Q

define fulminant C.difficile and abx used

A

hypotension OR ileus OR megacolon

IV metronidazole 500mg q8h
+ PO vancomycin 500mg QDS
+/- PR vancomycin 500mg QDS

10 days (14 days if sx not completely resolved)

47
Q

if fixadomicin available in SG?

A

no

48
Q

recurrent CDI definition

A

Defined as a resolution of CDI symptoms, followed by subsequent reappearance of symptoms after treatment has been discontinued

49
Q

RF for recurrence in CDI

A
  • administration of other antibiotics during or after initial treatment of CDI
  • a defective humoral immune response against C. difficile toxins
  • advanced age and
  • severe underlying disease
  • continued use of PPIs
50
Q

tx for first recurrence of C.difficile

A

Initially using fidaxomicin/ vancomycin
- PO fidaxomicin pulse
- PO vancomycin tapered/pulse

Initially using metronidazole
- PO vancomycin 125mg QDS x10d

51
Q

C.difficile monitoring

A
  • sx should resolve in 10 days, if not extend for another 4 days
  • additional diagnostics/ escalation of meds if poor response
  • no evidence for decrease recurrence if use >10-14 days
  • do not continue C.difficile tx because pt needs to continue concurrent abx

PR3151 Finals (7 decks)

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