Nervous system infections Flashcards
which people have a higher risk of developing infectious meningoencephalitis
⭡risk in neonates, elderly, immunocompromised, pregnancy, crowded enviroments
what are the mechanisms of infection that can cause a meningoencephalitis
hematogeneous dissemination
direct trauma
contagious spread
pathophysiology of hematogeneous dissemination for meningoencephalitis
hematogeneous dissemination → specially from the nasopharynx (most commonly Neisseria)
pathophysiology of direct trauma for meningoencephalitis
direct trauma → fractured skull, VP shunts, neurosurgical procedures, etc. (think about staph aureus and staph epidermidis)
pathophysiology of contagious spread for meningoencephalitis
contagious spread → otitis media, sinusitis (strep pneumo)
- remember that otitis media in children is commonly caused by the non typeable H.influenza, type B is uncommon because of vaccination
how do you distinguish meningitis and encephalitis
meningitis → Kerning and Brudzinski sign
encephalitis → focal neurological deficits
typical triad of bacterial meningoencephalitis
rapid onset fever, nuchal rigidity, headache or altered mentation
what’s the clinical presentation of meningoencephalitis
typical triad = rapid onset fever, nuchal rigidity, headache or altered mentation
hypotension, tachycardia, photophobia, emesis, altered mentation, seizures
Kerning and Brudzinski sign, papilledema, Cushing reflex
what do you expect to find in a lumbar puncture of a bacterial meningitis
⭡opening presure
cloudy fluid
pleocytosis (>1,000 mm^3, granulocytosis = neutrofiles)
⭡protein, ⭣glucose
what are the typical pathogens of a bacterial meningitis
S.pneumonia
N.meningitis
H. influenzae type B
Listeria
meningococcemia is caused by which pathogen
Neisseria meningitis
what’s the presentation of meningococcemia ? how does it work?
respiratory droplets (crowded environments) → colonizes nasopharynx → jumps to the CSF (hematogeneous dissemination)
endotoxin (LOS) → septic shock
presentation → purpura/petechiae
complication: waterhouse-friderichsen syndrome = acute adrenal insufficiency
do you give prophylaxis for someone that was closed with someone that now has meningococcemia?
prophylaxis is necessary for people with close contact !!
is there a vaccine for neisseria meningitis?
there is a vaccine = MenACWY
- you can still get the B serotype because we can’t vaccine against it since it’s fairly similar to humans
- even though it’s a risk people in the military get it (risk populations can get it → including people without their spleen)
most common cause of adult meningitis
strep penumonia
meningitis caused by strep penumo and neisseria are more common in people with ….
a prior splenectomy → no spleen = no antibodies = no opsonization
which pathogen that causes meningitis leaves the most sequels, including future trombosis
strep penumonia
which population is susceptible to an infection with listeria
Listeria happens in the old (elderly) and the young (neonates)
what’s the most common atypical bacteria that causes meningitis?
S. aureus (direct trauma, VP shunt)
what’s the clinical presentation of a viral meningitis
non specific signs/symptoms: low grade fever, malaise, myalgia, maculopapular rash +/- less severe meningeal signs
what do you expect to find in a lumbar puncture of someone with viral meningitis
⭡/- opening pressure
clear fluid
pleocytosis (10-500/mm^3, lymphocytosis)
⭡/- protein
normal glucose
what typical viruses cause viral meningitis
enteroviruses (MCC)
HSV
VZV
West Nile virus
St. Louis encephalitis virus
HIV
when is meningitis caused by enteroviruses more commonly found
most common in summer months
which are the most common enteroviruses that cause meningitis
- coxsackie virus → hand, foot, mouth disease
- echovirus
- poliovirus → myelitis
- adenovirus → least high-yield
which is the most important enterovirus that causes meningitis
coxsackie virus
HSV normally causes ———–, their lesions are normally in the ——– ——–
encephalitis
temporal lobe
characteristics of a HSV encephalitis
normally a temporal lobe encephalitis
Kluver-Bucy syndrome: bilateral temporal lobe lesions → HSV-1 encephalitis
damage to the amigdala = loss of the fear response, hyper-orality, hyper-sexuality, impulsive behaviour
damage to hippocampus = amnesia (typically anterograde)
West Nile virus is associated with ….
dead birds
subacute sclerosing panencephalitis:
persistent measles infection → inflammatory demyelinating, ⭡anti-measles IgG in CSF
what pathogenes cause the most common atypical meningoencephalitis
tuberculosis: mycobacterium tuberculosis, immunocompromised, insidious onset, AFB, ADA activity
- most common form of chronic meningitis
Lyme: Borrelia burgdoferi, late stage neuroborreliosis, CN VII palsy (bilateral), nocturnal parasthesias, mononeuritis multiplex
Cryptococcal: cryptococcus neoformans, immunocompromised (CD4+ <100), India ink, Latex agglutination test, narrow-based budding yeast
Rickettsial: Rickettsia spp., petechiae, tick exposure, non-classic bacterial LP results
primary amebic: naegleria fowleri, warm freshwater ponds, rapid onset fulminant disease, hemorrhagic (RBC in LP), fatal
- contiguous spread
what do you expect to see in a lumbar puncture of a patient with atypical meningitis
⭡opening pressure
pleocytosis (lymphocytes)
⭡protein
⭣glucose
characteristics of a patient with neonatal meningitis
- 0-3 months old
- lethargy, emesis, hypotonia, fever (or hypothermia), bulging fontanelle, high pitch crying, seizures
which pathogens typically cause neonatal meningitis
streptococcus agalactiae (group B)
- main one
E.coli
Listeria
enteroviruses (coxsackie virus)
how does a baby get infected with strep. agalactiae
streptococcus agalactiae (group B) → vaginal colonization → can ascend to the uterus → chorioamnionitis → fetus swallows it and gets into the lungs
mom has to be tested 25-27 GWs = vaginal swap → if positive give Gentamicin + Ampicillin
what do you expect to see in a MacConkey agar depending on the pathogen that causes neonatal meningitis
if you test a sample in MacConkey agar and:
- it doesn’t grow anything = gram (+) = strep, listeria
- if it grow something = gram (-) = e.coli (pink color)
which findings in a patient suggest an elevated ICP?
papilledema
altered mentation
hipotension
irregular respirations
focal neurological deficits
do you always do a lumbar puncture if you suspect the patient has an encefalitis?
only if the px doesn’t have any sings of an elevated ICP
what’s the pharmacological management for adult meningitis
- empiric: ceftriaxone + vancomycin + dexamethasone +/- ampicillin
- fungal: amphotericin B
- tuberculous: RIPE variants (ethambutol has poor CNS penetration)
- cryptococcal: amphotericin B + flucytosine
- lyme: ceftriaxone
- HSV: acyclovir
what’s the pharmacological management for neonatal meningitis
empiric = cefotaxime + ampicillin + gentamicin
general principles of infectious cerebral lesions
focal neurological deficits (eg. hemiparesis, aphasia), ⭡risk of seizures
avoid LP if suspect mass lesions of ⭡ ICP → risk of brain herniation
typical abscess pathogens
commonly polymicrobial (oral anaerobes → bacteroides)
- dental infections
Viridans streptococci (MCC) → subacute endocarditis
- mitral valve→ septic emboli
staph aureus
staph epidermidis → VP shunts, neurosurgical equipment
Atypical abscess/cyst-forming pathogens
nocardia → immunocompromised patient, partial acid fast, initial pulmonary disease
- inhaled
cryptococcus neoformans → pigeons/bird droppings, immunicompromised (CD4+ <100), india ink, latex agglutination test → “soap bubble” lesions (pseudocystitis)
toxoplasma gondii → cat feces, immunocompromised (CD4+ <100), multiple “ring-enchancing” lesions, microscopy with tachyzoites
- oral infection
taenia solium → consumption of raw pork, eosinophilia, cystic lesion(s) +/- invaginated scolex
Neurotoxic pathogens
JC virus → reactivation → PML, immunocompromised (CD4+ <200), asymethric T2-hyperintense lesions
primary CNS lymphoma → viral associations (EBV), immunocompromised (CD4+ <100), solitary variable (homogenous vs ring) enhancing lesions on CT with contrast
HIV encephalotogy → diffuse atrophy, immunocompromised, symmetric T2-hyperintense lesions
spongiform encephalopathy → misfolded proteins (PRPsc), startling myoclonus, rapidly progressing dementia, ⭡14-3-3 protein (CSF), triphasic periodic sharp waves (EEG)
- Creutzfeldt-Jakob disease(CJD)
