Meningitis Flashcards
Bacterial Meniginitis overview
Most common form of suppurative CNS infections:
Responsible organisms for meningitis
streptococcus pneumoniae ( 50%)
Neisseria meningitis (25%)
the causative organism of recurring epidemics q 8-12 years
group B streptococcus ( 15%)
listeria monocytogenes ( 10%)
staphylococci and pseudomonas aeruginous: hospital-acquired from brain surgery
Acute purulent infection within subarachnoid space
CNS inflammatory reaction
decreased LOC, ICP seizures, and stroke
irritaion of meniges and SAS and parechyma:
meningoencephlitis
meningitis infection initiated by
nasopharyngeal colonization: enters the bloodstream
Avoidance of classic bactericidal activity:
polysaccharide capsule
Access to CSF:
bacteria rapidly multiples
lack of immune defenses in CSF
A direct consequence of cytokines and chemokines:
increase blood-brain barrier permeability
vasogenic edema
leakage of serum proteins
inflammatory reaction induces invasion
neurologic manifestaions and complications
meningitis findings
Classic triad: fever, headache, nuchal rigidity
decrease LOC
light sensitivity
petechial or purpuric skin lesions
trunk and lower extremities
palms and soles
kerning’s sign
brudzinski sign
meningitis clinical findings
Focal seizures ( 20-40%)
focal arterial ischemia or infarction
cortical venous thrombosis with hemorrhage
focal edema
generalized seizure
hyponatnatremia
cerebral anoxia
toxic effects of antimicrobial agents
raised intracranial pressure ICP
cause of obtunded or comatose state
papilledema
poor pupillary response
CN VI palsy
decebrate posturing
crushing reflex: bradycardia HTN and irregular resp
cerebral herniation
opening pressures > 400
meningitis workup
lab: CBC, CMP, ESR, CRP
blood cult : initiate ABX after BCx
neuroimaging:
CT or MRI
prior to LP
HX of head trauma:
normal LOC
no focal nerulogic deficit
LP
CSF fluid analysis
CSF fluid in meningitis
Opening pressure : > 180
WBC: 10-100000 neutrophil predominant
Glucose < 2.2 ( 40mg dl)
CSF serum glucose <0.4
RBC absent
Protein < 0.45
Gram stain positive > 60%
culture positive > 80%
PCR detects bacterial DNA
Bacterial meningitis treatment
Immediate treatment:
Antibiotic initiated within 60 minutes
Dexamethasone
Community-acquired abx coverage:
Cover empirically:
Rocephin or cefepime and vancomycin ( 3rd generation)
Add acyclovir:
HSV encephalitis
ampicillin: added due to higher risk of listeria
> 55 years old
organ transplantation
malignancy
immunosuppression
all at risk for L monocytogenes
flagyl
cover gram-negative anaerobes (otitis, sinusitis, or mastoiditis )
Hospital-acquired coverage:
staphylococci and pseudomonas aeruginosa
Vancomycin and meropenem
management of ICP
elevation of HOP 30-45 degrees
intubation
mannitol
Viral meningitis
not nationally reported - 60-75 K per year
more often in temperate climates
increase during non-winter months
most common viruses;
echoviruses
coxsackieviruses
enteroviruses
varicella-zoster
HSV 2 > 1
HIV
arboviruses
viral meningitis clinical findings
immunocompetent adult patient
headache
frontal or retro-orbital
photophobia
fever
meningeal irritation
nuchal rigidity
malaise
myalgia
anorexia
nausea and vomiting
abdominal pain
mild lethargy or drowsiness
marked change in LOC not present
work up for viral meningitis
Lab:
CBC, CMP, ESR, CRP, HIV
Lumbar puncture:
PCR check CSF analysis :
Diagnostic of choice
CMV, EBV, VZV, HHV-6
WNV-specific CSF IGM
Viral culture:
generally poor
oligoclonal gamma globulin bands : number of viral infections will prove virus
serum serologic studies
WNV
HSV
VZN
CMV
EBV
CSF fluid for viral meningitis
opening pressure : 100-350
WBC 25-500 lymphocytes predominate
RBC absent
Glucose normal
protein 20-80
gram stain not detected
culture virus detected
PCR virus detected
