Audia- Meningitis/Encephalitis Flashcards
Neisseria meningitidis
E. coli
is an inflammation (swelling) of the protective membranes covering the brain and spinal cord (the meninges). A bacterial or viral infection of the fluid surrounding the brain and spinal cord usually causes the swelling
Meningitis
is inflammation of the brain
Encephalitis
_____encephalitis results from direct infection of the brain (e.g., rabies)
Primary Encephalitis
______encephalitis results when infection spreads from meninges to the brain
Secondary Encephalitis
where to obtain CSF
L3-L5 (lumbar puncture)
mostly lymphocytes
normal glucose
normal or mildly elevated protein
(CSF)
viral infection
mostly PMNs (neutrophils seen)
decreased glucose
elevated protein
(CSF)
bacterial infection
what should be on differential if patient is immunocompromised
fungal infection
major causes of bacterial meningitis in the US
S. pneumoniae
group B strep
N. meningitidis
H. influenzae
Listeria monocytogenes
E. coli
capsular K antigen—protects from complement (anti-phagocytic) and can disseminate
neonatal meningitis from E. coli
obligate intracellular, actin rocket, lunchmeat, and transmitted from mom to child
neonatal meningitis from Listeria
risk factors include:
age
group setting
medical hx
healthcare workers
bacterial meningitis
how do Group B strep and E.coli transmit bacterial meningitis
vertical (mother to baby)
H. influenzae and S. pneumoniae transmission of bacterial meningitis
horizontal via resp. droplets and aerosols
Horizontal transmission by direct sharing of respiratory or throat secretions (saliva/spit) – kissing, sharing drinks, lengthy contact (cohabitants)
N. meningitidis
also has oral-fecal transmission
E. coli
can cause meningitis by contaminating food
E. coli and Listeria
sudden onset fever, HA, stiff neck (3-4 days post-exposure)
bacterial meningitis
Other symptoms include nausea, emesis (vomiting), photophobia (light sensitivity), altered mental status
bacterial meningitis
may not present classically and instead may be slow/inactive, irritable, vomit, poor feeding, abnormal reflexes (if infected with bacterial meningitis)
newborns and babies
S. pneumoniae
gram + lancet shaped cocci
capsule-producing (can disseminate well)
S. pneumoniae
alpha hemolytic; grows on blood agar
S. pneumoniae
to treat:
vancomycin + ceftriaxone
S. pneumoniae
interacts w/ D-Ala D-Ala, and blocks building of peptidoglycan and cross linking
Vancomycin
(hit the penicillin binding proteins)—PBPs are crucial for bacteria to build cell wall
Ceftriaxone
why use vanco + ceftriaxone
empiric therapy for the other causes of meningitis before you get the results
type of vaccine that will only generate IgM response
polysaccharides
conjugate ______ to a protein in order to get system turned on and get T cell engagement (T cells are important for inducing, class switching, and affinity maturation)
polysaccharide
to prevent S. pneumoniae
Vaccination (polyvalent conjugate against capsular polysaccharide or polysaccharide vaccine)
gram - diplococci
capsule producing (can disseminate well)
N. meningitidis
grows on blood agar
can have sequalae of limb loss, deafness, nervous system damage, brain damage
N. meningitidis
treat with ceftriaxone
penicillin G upon definitive diagnosis
N. meningitidis
to prevent ______: Vaccination (tetravalent conjugate against capsule or monovalent recombinant protein vaccine)
N. meningitidis
gram - pleomorphic coccobacillus
H. influenzae
type b (Hib) and Non-b
grows on chocolate agar
H. influenzae
treat with third-generation cephalosporins (cefotaxime and ceftriaxone)
H. influenzae
to prevent H. influenzae (type b only)
polysaccharide conjugate
20% of _____ survivors suffer permanent hearing loss or other neurological issues
H. influenzae type b
mild cases of this are usually self-limiting
treat with supportive care
viral meningitis
Enteroviruses (coxsackieviruses, echoviruses, non-polio enteroviruses) are the major cause of this in the US
viral meningitis
Measles
Mumps
Influenza
Herpes viruses (EBV, HSV, VZV)
Arboviruses (vector-borne disease)
other causes of viral meningitis in the US
coxsackieviruses, echoviruses, non-polio enteroviruses
Enteroviruses (oral-fecal route)
hand-foot-mouth disease
Coxsackie type A
require T cells to “help” B cells * elicited by protein antigens * involve follicular B cells (reside in follicles of secondary lymphoid organs)
T cell dependent antibody response
do not require T cells to “help” B cells * elicited by polysaccharide, lipid & nucleic acid antigens * involve B-1 B cells (mucosal tissues, peritoneum) and marginal zone B cells (spleen)
T cell independent antibody response
Immunosuppression is a major risk factor (steroids, HIV, organ transplants)
Geographic risk factors
fungal meningitis
Cryptococcus (meningoencephalitis)
Histoplasma (central and eastern US)
Blastomyces (Midwest, south central, southeastern US)
Coccidiodies (southwest, south-central Wa, parts of Mexico and Central/South America)
Candida (highest yield)
major causes of fungal meningitis in US
endemic in mississippi and ohio river valleys
hides in macrophages
bat and bird droppings
systemic
Histoplasmosis
endemic in eastern and central US, great lakes
broad based budding
soil and decaying leaf matter
systemic
Blastomycosis
opportunistic
adhesion and yeast to hyphal transition
candida
toxicity of anti-fungals
liver and renal
target cell wall
fungicidal
(polyenes—-targets cell wall)
Amphotericin B and Nystatin
targets ergosterol synthesis
fungistatic
(-azoles)
Fluconazole
targets ergosterol synthesis
Terbinafine
least toxic
targets beta1,3 glucan
Echinocandins
targets fungal DNA/RNA synthesis
Flucytosine
Rare form of meningitis called eosinophilic meningitis/meningoencephalitis (EM)
travel hx important
parasitic meningitis
Angiostrongylus cantonensis (neurologic angiostrongyliasis)
Baylisascaris procyonis (baylisascariasis; neural larva migrans)
Gnathostoma spinigerum (neurognathostomiasis)
major causes of parasitic meningitis
can get this from swimming in warm fresh water w/ soil (florida and texas)
prevalence low
brain eating
Amebic meningitis
West Nile virus causing encephalitis
encephalitis
Rabies virus causing encephalitis
Often causes mild flu-like symptoms (fever, headache)
Severe cases can lead to altered mental status, seizures, loss of motor control, weakness, altered senses
viral encephalitis
HSV
West Nile virus
EEEV
Rabies virus
causes of viral encephalitis
2 main types of Arboviruses (transmitted by mosquitoes) causing viral encephalitis
West Nile Virus
Eastern Equine Encephalitis Virus
Flavivirus family
+ve sense ssRNA; Icosahedral nucleocapsid; enveloped
Most common arboviral encephalitis in US
West Nile Virus
Togavirus family
+ve sense ssRNA; Icosahedral nucleocapsid, enveloped
Rare in the US, but severe disease (50% mortality)
Eastern Equine Encephalitis Virus
________viruses are the ones that look, smell, and taste like mRNAs (once virus gets inside cell, that viral message can be immediately translated, can make one long protein that turns into active subunits of virus)
+ sense ssRNA
leave host cell by a budding process and pick up membrane from that host
so the viral major glycoproteins will be in that membrane and helps get in to next cell
enveloped virus
don’t get high enough viral loads that the mosquito could pick up enough and go infect another person
dead end hosts (humans and horses)
to diagnose West Nile virus
NAAT (requires reverse transcriptase)
normal PCR tests done in the lab only works on DNA; so for ______viruses, gotta convert RNA into DNA (like HIV and lenti viruses use reverse transcriptase to convert their RNA genome into DNA)
RNA viruses
to diagnose EEEV
isolate virus from blood and brain tissue, CSF
only vaccine for EEEV
killed vaccine for horses
how to treat WNV and EEEV
supportive care
large bullet shaped virus particle
-sense ssRNA
Rhabdovirus (rabies)
_____sense ssRNA (must bring luggage with them (viral RNA dependent RNA polymerase) that will be used to make messages in order for production of viral protein); must go through transcription step first
negative
major antigenic determinant is viral glycoprotein
Rhabdovirus
Easily treatable if you catch it before symptoms manifest (give IVIG)—-passive transfer of immunity (IgG will neutralize virus and prevent it from spreading)
Rhabdovirus (rabies)
virus replicates so slowly, can actually get vaccinated after exposure to this
rhabdovirus (rabies)