Audia- Meningitis/Encephalitis Flashcards by Madeline Wing

Neisseria meningitidis

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E. coli

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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

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is inflammation of the brain

Encephalitis

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_____encephalitis results from direct infection of the brain (e.g., rabies)

Primary Encephalitis

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______encephalitis results when infection spreads from meninges to the brain

Secondary Encephalitis

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where to obtain CSF

L3-L5 (lumbar puncture)

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mostly lymphocytes
normal glucose
normal or mildly elevated protein
(CSF)

viral infection

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mostly PMNs (neutrophils seen)
decreased glucose
elevated protein
(CSF)

bacterial infection

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what should be on differential if patient is immunocompromised

fungal infection

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major causes of bacterial meningitis in the US

S. pneumoniae
group B strep
N. meningitidis
H. influenzae
Listeria monocytogenes
E. coli

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capsular K antigen—protects from complement (anti-phagocytic) and can disseminate

neonatal meningitis from E. coli

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obligate intracellular, actin rocket, lunchmeat, and transmitted from mom to child

neonatal meningitis from Listeria

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risk factors include:
age
group setting
medical hx
healthcare workers

bacterial meningitis

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how do Group B strep and E.coli transmit bacterial meningitis

vertical (mother to baby)

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H. influenzae and S. pneumoniae transmission of bacterial meningitis

horizontal via resp. droplets and aerosols

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Horizontal transmission by direct sharing of respiratory or throat secretions (saliva/spit) – kissing, sharing drinks, lengthy contact (cohabitants)

N. meningitidis

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also has oral-fecal transmission

E. coli

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can cause meningitis by contaminating food

E. coli and Listeria

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sudden onset fever, HA, stiff neck (3-4 days post-exposure)

bacterial meningitis

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Other symptoms include nausea, emesis (vomiting), photophobia (light sensitivity), altered mental status

bacterial meningitis

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may not present classically and instead may be slow/inactive, irritable, vomit, poor feeding, abnormal reflexes (if infected with bacterial meningitis)

newborns and babies

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S. pneumoniae

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gram + lancet shaped cocci
capsule-producing (can disseminate well)

S. pneumoniae

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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)