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3151 > Meningitis/ C. diff > Flashcards

Meningitis/ C. diff Flashcards

1
Q

causes of meningitis

A

infection (bacteria/ virus/ fungi/ parasite/ TB/ syphilis)

Drugs (bactrim, ibuprofen)

Autoimmune disease

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2
Q

Which populations are more susceptible to bacterial meningitis?

A

Men (> female)
More common in children

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3
Q

Pathogenesis of meningitis

A

immune deficiency/ prolonged close contact/ travel to endemic areas
-> predisposes infection & colonisation by bacteria that can cause meningitis
*strep pneumo, N. meningitidis, H. influenzae, L. monocytogenes etc
-> Bacteria gain entry into the body via various mechanisms:
1. invasion of mucosal surface
2. spread from para-meningeal focus (otitis media, sinusitis etc)
3. penetrating head trauma
4. anatomic defects in meninges
5. previous neurological procedures
-> in a susceptible host: bacteria enter CSF & colonise meninges *esp arachnoids -> bacterial meningitis

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4
Q

Risk factors/ predisposing factors for bacterial meningitis

A

head trauma
CNS shunts
neurosurgical patients
CSF fistula/ leak
local infections (otitis media, sinusitis)
immunosuppression
splenectomised pts
congenital defects

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5
Q

symptoms of bacterial meningitis

A

fever
chills
*(classic triad) headache/ backache/ nuchal (neck) rigidity
nausea, vomiting, anorexia, poor feeding habits in infants
petechiae/ purpura (specific for neisseria meningitis)

physical signs:
Kernig sign (while supine, 1 leg raised 90degrees -> pain)
Brudzinski sign ( while supine, legs bend as neck is lifted from ground)
Bulging fontane: ‘soft’ spot @ centre of infant’s skull (natural)

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6
Q

diagnosis for bacterial meningitis (lab measures etc)

A

History & physical examination (any headache/backache/neck rigidity, Kernig/Brudzinski sign)

Blood cultures (>50%: +ve)

Lumbar puncture:
Opening pressure - elevated
CSF composition - elevated WBCs (>100/mm3) & protein (>1.5g/L), lowered glucose (<0.4)
CSF gram stain & culture
CSF PCR
General lab findings (WBC, CRP, calcitonin) *non-specific for bact. meningitis
Radiology (brain imaging) *for differential diagnosis

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7
Q

Empiric therapy for bacterial meningitis in NEONATES

A

Likely pathogen: Group B Strep (S. agalactiae) // E.coli // Listeria monocytogenes

Abx: IV ceftriaxone (2g q12h(?)) + IV ampicillin (2g q4h(?))
*ampi - covers listeria

Duration of therapy:
Group B strep - 14-21d
Listeria - =/>21d

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8
Q

Empiric therapy for bacterial meningitis for INFANTS (1-23mths)

A

Likely pathogen: Strep pneumo // N. meningitidis // E.coli // Group B Strep (S. agalactiae)

Abx: IV Ceftriaxone (2g q12h(?)) + IV Vancomycin (25-30mg/kg LD, 15mg/kg q8-12h until AUC/MIC 400-600(?))

*vanco: covers strep pneumo

Duration of therapy
Strep pneumo - 10-14d
N. meningitidis - 5-7d
Group B Strep - 14-21d

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9
Q

Empiric therapy for bacterial meningitis in children & adult (2-50y/o)

A

Likely pathogen: strep pneumo // n. meningitidis

Abx: IV Ceftriaxone (2g q12h) + IV vancomycin (25-30mg/kg LD, 15mg/kg q8-12h until AUC/MIC 400-600)

*vanco covers strep pneumo

Duration of therapy:
Strep pneumo - 10-14
N. meningitidis - 5-7

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10
Q

Empiric therapy for bacterial meningitis in adults (>50y/o)

A

Likely pathogen: Strep pneumo // N. meningitidis // Listeria monocytogenes // aerobic GN bacilli (E.coli/Klebsiella)

Abx: IV Ceftriaxone (2g q12h) + IV Vancomycin (25-30mg/kg LD, 15mg/kg q8-12h until AUC/MIC of 400-600) + IV Ampicillin (2g q4h)

*vanco covers strep pneumo, ampi covers listeria

Duration of therapy:
N. meningitidis: 5-7
Listeria monocytogenes: =/>21d

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11
Q

Culture-directed therapy for bacterial meningitis

A
  1. Strep pneumo (10-14d)
    pen sensitive - ampicillin, Pen G
    pen resistant, ceph susceptible - ceftriaxone
    pen & ceph resistant - vanco + rifampicin
  2. N. meningitidis (5-7d)
    pen sensitive - pen G, ampicillin
    pen resistant OR mild allergy - ceftriaxone
  3. Listeria monocytogenes (>/= 21d)
    pen sensitive - Pen G, ampicillin
    **pen ALLERGY - co-trimoxazole, meropenem
  4. Group B Strep (14-21d)
    pen sensitive - Pen G, ampicillin
    pen MILD allergy - ceftriaxone

Doses (all IV):
*Pen G - 4 MU q4h (not inside dosing table)
Ampicillin - 2g q4h
Ceftriaxone - 2g q12h
Vanco - 25-30mg/kg LD, 15mg/kg q8-12h until AUC/MIC of 400-600
*Rifampicin - 300mg q12h (not inside dosing table)
Co-trimoxazole
Meropenem - 2g q8h

**IF CULTURE -VE: STILL TREAT WITH EMPIRIC ABX FOR 14D (start from 1st day of ACTIVE therapy; unless MSSA bacteremia start counting from 1st day of culture -ve)

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12
Q

Adjunctive therapy in bacterial meningitis

A

Corticosteroids - Dexamethasone
* recommended for pts w bacterial meningitis beyond neonatal age (>6 weeks)
- allows LESS hearing loss & other neurologic sequelae in H. influenzae & S. pneumoniae meningitis
- allows LESS mortality in S. pneumoniae meningitis
**may decrease antibiotic penetration (less inflammation)
ADR: mental status change, hyperglycemia, HTN
- Administer 10-20mins BEFORE or AT SAME TIME as FIRST dose of abx
- (Adult dose) 10mg q6h (UP TO 4D)

*stop if pt NOT having bacterial meningitis/ species not H. influenzae/ Strep pneumo

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13
Q

Monitoring response from bacterial meningitis therapy

A
  • Resolution of S&S: Most pts improve within 48h
  • no need to repeat culture if improving clinically
    *if did not improve within 48h -> brain imaging to check for cerebrovascular complications eg. stroke, brain abscess
  • ADR monitoring:
    morbidity common in bacterial meningitis
  • Focal neurological deficits (hearing impairment, cognitive impairment, seizures)
  • After bacterial meningitis infection: pt at HIGH RISK of long-term neurological & neuropsychological deficits (impair daily life activities & QoL)
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14
Q

Chemoprophylaxis for close contacts of pt with bacterial meningitis

A
  • for Neisseria Meningitidis
  • Risk of meningococcal disease increased 400-800x for close contacts (HIGHEST RISK: household contacts)
  • Beneficial for CLOSE CONTACTS (household/ day care) or EXPOSURE TO ORAL SECRETIONS of index case
  1. Rifampicin (PO)
    adults: 600mg q12h, 4 doses
    children: 10mg/kg q12h, 4 doses
    infants (<1mth): 5mg/kg q12h, 4h
  2. Ciprofloxacin (PO) *ADULTS ONLY
    500mg, 1dose
  3. Ceftriaxone (IM)
    125-250mg, 1 dose
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15
Q

Features of C.diff & its infection

A

Gram +ve
SPORE-forming
ANAEROBIC bacillus
TOXIGENIC strain produces TOXIN A & B
*more clinically impt toxin: toxin B

causative organism of abx-associated DIARRHOEA & COLITIS
*most common cause of nosocomial diarrhea

SPORES transmission: by faecal-oral route

Presentation ranges from ASYMPTOMATIC to FULMINANT disease

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16
Q

Pathogenesis of C. diff infection

A

colonisation of intestinal tract with C. diff via faecal-oral route (facilitated by abx use: disruption of barrier function of normal colonic flora; provide niche for C Diff multiplication & toxic production)
*TOXIN A & B -> inflammation & diarrhea

*asymptomatic carriers carry ANTIBODIES (high serum levels) which are protective against C diff toxins.

17
Q

Risk factors for C. diff infection

A

Advanced age >65y/o
multiple/ severe comorbidities
immunosuppression
history of CDI
GI surgery
tube feeding
prior hospitalisation (last 1y)
duration of hospitalisation
residence in nursing home/ long-term care facilities
*use of gastric acid suppressive therapy
use of abx

18
Q

Antibiotics that may cause/ protects against C. diff

A

almost all antibiotics can cause C. diff infection

Greatest risk:
1. Clindamycin (OR 16.8)
2. 3rd & 4rd gen cephalosporins (OR 5.68)
3. Fluoroquinolones (OR 5.5)
*greatest risk while on abx but still elevated until 12wks later

PROTECTIVE: doxycycline/ tigecycline
- Active against C. diff growth + inhibits toxin production
- Minimal effect on gut flora

19
Q

C. diff infection pt control & prevention

A
  1. isolation
    - private room w dedicated toilet OR prioritise pts w stool incontinence
  2. hand hygiene
  3. environmental cleaning *sporicidal agents
  4. antimicrobial stewardship

Other modalities to reduce c diff:
- avoid acid suppression (stop any unnecessary use of PPIs)
- use probiotics (but not routinely recommended)

20
Q

Clinical presentation for the various stages of C diff infection

A

*watery diarrhea (=/>3 unformed stools in 24h)

mild: DIARRHEA, abdominal cramps

moderate: DIARRHEA, FEVER, NAUSEA, MALAISE // abdominal cramps & distention // *LEUKOCYTOSIS (elevated WBC count // HYPOVOLEMIA
*WBC <15 x 10^9/L AND SCr <133umol/L (1.5mg/dL)

severe: FEVER, DIARRHEA, diffused abdominal cramps & distension, WBC >/= 15 x 10^9/L OR SCr >/= 133umol/L (1.5mg/dL)

fulminant: HYPOTENSION/SHOCK, ILEUS (no peristalsis), MEGACOLON (severe inflammation leading to perforation)

21
Q

Diagnosis of C. diff infection

A
  1. presence of diarrhea (>/= 3 unformed stools within 24h)
    OR
    radiographic evidence of ileus/ toxic megacolon
  2. +ve stool test result for C.diff OR its toxins
    OR
    colonoscopic/ histopathologic evidence of pseudomembranous colitis
    *lab stool test CANNOT distinguish btw colonisation & infection; testing ONLY for symptomatic pts (& limited to pts w DIARRHEA)
    ^ensure pt has not taken any laxative 2d prior to test, DO NOT REPEAT <7d (>60% pts w favourable clinical response still continue to test +ve)
22
Q

Treatment principles for C. diff infection

A
  1. DO NOT TREAT asymptomatic pts with +ve C. diff test (confirm symptoms consistent w CDI EXIST prior to prescribing therapy)
  2. if possible, discontinue any antibiotics NOT specifically treating CDI
  3. if additional antibiotic therapy necessary:
    - select narrowest spectrum agent possible
    - avoid agents with STRONG association w CDI (clinda/ 3/4 gen ceph/ FQ)
23
Q

empiric therapy for INITIAL episode for c diff infection

A

NON-SEVERE: WBC <15 x 10^9/L AND SCr <133umol/L (1.5mg/dL)
1st line: PO Fidaxomicin 200mg BD OR PO Vancomycin 125mg QDS
Alternative: PO metronidazole 400mg TDS

SEVERE: WBC >15 x 10^9/L OR SCr >133 umol/L (1.5mg/dL)
1st line: PO Fidaxomicin 200mg BD OR PO Vancomycin 125mg QDS

FULMINANT: WBC >15 x 10^9/L AND SCr >133 umol/L (1.5mg/dL)
1st line: IV metronidazole 500mg q8h + PO Vancomycin 500mg QDS +/- per-rectal (enema) Vancomycin 500mg QDS

Duration of therapy: 10d for ALL (may extend to 14d if symptoms not completely resolved)
*fidaxomicin preferred (over vanco/ metro) due to lower recurrence rate BUT not avail in SG

24
Q

Monitoring response in c diff infection

A
  1. Resolution of symptoms: should resolve in 10d, otherwise extend another 4d of treatment (no evidence for lowered recurrence for >14d treatment)
    *IF POOR RESPONSE: additional diagnostics/ consider escalation of pharmacologic treatment
    **DO NOT CONTINUE TREATMENT >14d if pt needs to continue concurrent abx
  2. culture
    DO NOT repeat culture <7d (>60% of pts still test +ve despite clinical response to treatment)
  3. ADR
25
Q

Recurrent CDI definition & prevalence

A

*pt recovers from CDI (resolution of CDI symptoms) -> subsequent REAPPEARANCE of symptoms AFTER treatment has been discontinued

~30% of patients experience recurrent CDI WITHIN 30D of treatment

26
Q

risk factors for recurrent CDI

A
  • administration of OTHER abx during/ after initial treatment for CDI
  • DEFECTIVE humoral immune response against C. diff toxins
  • advanced age
  • severe underlying disease
  • continued use of PPIs
27
Q

Treatment for recurrent CDI

A

1st recurrence
(if fidaxomicin/ vanco used for initial episode)
PO fidaxomicin 200mg BD x10d
OR
PO fidaxomicin 200mg BD x 5d THEN 200mg every other day x 20d
OR
PO vanco tapered/ pulse *125mg
(if metronidazole used for initial episode)
PO Vancomycin 125mg QDS x 10d

2nd/ subsequent recurrence
PO fidaxomicin 200mg BD x 5d THEN 200mg EOD x20d
PO vanco tapered/pulse *125mg
PO vanco 125mg QDS x 10d THEN RIFAXIMIN 400mg TDS x 20d
Faecal microbiota transplant

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