IC17 CA- bacterial meningitits and C.difficile Flashcards
define meningitis
inflammation of the leptomeninges
parts of leptomeninges
- arachnoid
- subarachnoid space (cerebrospinal fluid)
- pia mater
causes of meningitis
- infection (bacteria/septic meningitis, virus, fungal, parasitic, syphilis)
- drugs (bactrim, ibuprofen)
- autoimmune diseases
incidence of bacteria meningitis
- more in africa population
- male > female
- common in children
RF bacteria meningitis
- 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
how does bacteria gain entry into the body for meningitis
- invasion of mucosal surface -> hematogenous spread to brain
- spread from para-meningeal focus (otits media, sinusistis)
- penetrating head truama
- anatomical defects in meninges
- previous neurological procedures
symptoms of bacterial meningitis
- 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
physical signs of bacterial meningitis
- Kernig sign (back pain when leg raised)
- Brudzinski sign (neck raised, leg bent)
- Bulging fontane (usually in babies)
diagnosis of bacterial meningitis
- history and physical examination
- blood cultures
- lumbar puncture
- elevated opening pressure
- CSF composition
- CSF gram-stain and culture
- CSF PCR
normal CSF
- glucose
- protein
- WBC
glucose: 2.6–4.5 mmol/L
CSF : blood > 0.66
protein: <0.4 g/L
WBC: <5 cells/mm3
bacterial meningitis CSF
- glucose
- protein
- WBC
glucose: very low
CSF : blood > 0.4
protein: >1.5 g/L
WBC: >100 cells/mm3 (mostly neutrophils) -> pleocytosis
viral meningitis CSF
- glucose
- protein
- WBC
glucose: normal to slightly low
protein: normal to slightly raised
WBC: 5-1000 cells/mm3 (mostly lymphocytes)
lab findings for bacterial meningitis
general lab findings (WBC, CRP, procalcitonin)
- signs of systemic infection
- non specific for bacterial meningitis
radiology- brain imaging (CT/MRI) for meningitis
- not required for diagnosis (usually only for differential diagnosis)
- MAY BE DONE prior to lumbar puncture (prevent risk of brain herniation)
meningitis: when should abx be started?
Antibiotic should be started as soon as possible (within 1 hour)
bacterial meningitis likely organism in neonates (<1yo) and abx used
- Grp B streptococcus (strep agalactiae)
- E.coli
- Listeria monocytogenes
- IV ceftriaxone + ampicillin (for Listeria)
bacterial meningitis likely organism in infants and children (1-23 mths) and abx used
- Streptococcus pneumoniae
- Neisseria meningitidis
- Strep agalactiae
- E.coli
- IV ceftiaxone + vancomycin (vanco to cover resistant strep pneumoniae)
bacterial meningitis likely organism children and adults (2-50 yo) and abx used
- Strep pneumoniae
- Neisseria meningitidis
- IV ceftriaxone + vancomycin
bacterial meningitis likely organism adults (>50 yo) and abx used
- Strep pneumoniae
- Neisseria meningitidis
- Listeria monocytogenes
- gram negative bacilli (E.coli, Klebs)
- IV ceftriaxone + vancomycin + ampicillin
culture directed for Strep pneumoniae
(pen susceptible) IV pen G, ampicillin
(pen resistant, cephalosporin susceptible) ceftriaxone
(pen, ceph resistant) vancomycin + rifampicin
duration: 10-14 days
IV rifampicin 300mg q12h
culture directed for Neisseria meningitidis
(pen susceptible) IV pen G, ampicillin
(pen resistant, mild allergy) ceftriaxone
duration: 5-7 days
culture directed Listeria monocytogenes
(pen susceptible) IV pen G, ampicillin
(pen allergy) co-trimoxazole, meropenem
duration >21days
culture directed Grp B strep (strep agalactiae)
(pen susceptible) IV pen G, ampicillin
(pen resistant, mild allergy) ceftriaxone
duration: 14-21 days
if culture negative how? (Meningitis)
empiric abx for at least 14 days (may be extended)
bacterial meningitis - adjunctive corticosteroids
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
bacterial meningitis - therapeutic response
- 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
abx use in meningitis must:
- distribute to CSF (achieve adequate CSF concentrations) - usually high dose, IV
- active against likely pathogens
- does not aggravate CNS morbidity (eg seizures)
- imipenem and cefepime increase risk of seizures
meningitis: RF for close contact
exposure to oral secretions of pt with bacterial meningitidis
chemoprophylaxis for close contact for meningitis
- rifampicin PO
(adults) 600mg q12hr x4 doses
(children) 10mg/kd q12hrs x4 doses
(infants <1mth) 5mg/kg q12hrs x4 doses - ciprofloxacin 500mg PO x1 dose
- ceftriaxone 125-250mg IM x1 dose
what kind of bacteria is Clostridoides difficile?
- what are the toxins strains produced
- how are spores transmitted?
gram positive, spore forming anaerobic bacillus
- produces toxin A and B
- transmitted by fecal-oral route
can C.difficle be asymptomatic?
yes
asymptomatic carriage to fulminant disease
describe pathogenesis of C.difficile
- 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
why are some people asymptomatic carriers
they have antibodies to the toxins (more than normal)
C.difficile: RF
- 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)
which abx has increased risk of developing CDI
all abx
greatest risk:
- clindamycin
- 3rd/4th gen cephalosporins
- fluroquinolones
highest risk while receiving abx, elevated up to 12 weeks later
which abx has protective effect against developing CDI
doxycycline
tigecycline
- inhibits toxin production
- minimal effects on gut flora
CDI infection control and prevention
- isolation
- hand hygiene
- environmental cleaning
- antimicrobial stewardship
CDI: Recognise the critical role of Antimicrobial Stewardship in reducing incidence of CDI
protective effect with reduce use abx
other modalities to reduce Cdiff
- acid suppression (reduce unnecessary PPI)
- probiotics (to reestablish microbiota)
Clinical presentations of C.difficile
(mild, moderate, severe)
- 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)
dx of C.difficile
- 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
which grp of patients should CDI testing be done in?
symptomatic pt only
lab stool test cannot differentiate btw colonisation and infection
things to note before doing stool test for C.difficile
- 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
management of C.difficile (tx principles)
- 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
define non severe C.difficile and abx used
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)
define severe C.difficile and abx used
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)
define fulminant C.difficile and abx used
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)
if fixadomicin available in SG?
no
recurrent CDI definition
Defined as a resolution of CDI symptoms, followed by subsequent reappearance of symptoms after treatment has been discontinued
RF for recurrence in CDI
- 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
tx for first recurrence of C.difficile
Initially using fidaxomicin/ vancomycin
- PO fidaxomicin pulse
- PO vancomycin tapered/pulse
Initially using metronidazole
- PO vancomycin 125mg QDS x10d
C.difficile monitoring
- 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
