micro Flashcards
what type of genome does poliovirus have?
+ssRNA
what type of genome do polyoma viruses have?
circular dsDNA
what are the two human polyoma viruses and what do they cause?
BK: little disease, seen in urine of AIDS patients
JC: PML
where do replication and assembly occur for polyoma viruses?
both in nucleus
what are the T antigens?
early genes in polyoma virus replication: initiate DNA replication and responsible for transformation
small and large: immortalize cells
small and medium: transform cells
what is progressive multifocal leukoencephalopathy? what is the pathogenesis?
progressive demyelinating disease of CNS caused by JC virus
infects and lyses oligodendrocytes
what are the three main symptoms of PML?
clumsiness, progressive weakness, speech problems
how is PML treated in AIDS and transplant patients?
AIDS: optimize HAART therapy->50% mortality
transplant: alter (don’t halt) immunosuppressive therapy->still 80% mortality
what is Kuru? what is its presentation? how is it transmitted?
prion disease in Papua New Guinea transmitted by ritualistic cannibalism: “tremble with fear”
what is the primary and secondary presentation of Creutzfeldt-Jakob disease? how does it end?
- dementia and myoclonus
- ataxia/cerebellar dysfunction
- akinetic mutism
what prion disease has been shown to be transmitted by dural grafts, corneal grafts, pituitary-derived hGH? which have short incubation?
Creutzfeldt-Jakob disease
dural and corneal grafts
how is variant Creutzfeldt-Jakob disease transmitted?
beef products and blood
which is more contagious and why: vCJD or CJD?
vCKD: also infects tonsils, spleen, lymph nodes, appendix
->diagnose by tonsil biopsy
what are the primary manifestations of vCJD? what is the end stage presentation?
- anxiety and depression
- sensory abnormalities, esp. visual late
- akinetic mutism
what is required to get vCJD?
vCJD: methionine at codon 129
how is GSS disease contracted
familial, AD
what prion diseases show amyloid plaques?
GSS
what is the primary presentation of GSS?
gait abnormalities and ataxia
-no dementia
which prion disease actually rarely shows spongiform changes?
fatal familial insomnia
what is the presentation of FFI?
sleep disturbances and autonomic dysfunction
name the prion disease according to presentation: insomnia and autonomic dysfunction; dementia and myoclonus; ataxia and gait abnormalities; anxiety/depression/sensory abnormalities
FFI, CJD, GSS, vCJD
what bacteria cause meningitis in infants?
GBS, G- enteric bacilli, Listeria
what bacteria cause meningitis in children 3mo-2yr?
S. pneumo, Neisseia, H. flu type B
what bacteria cause meningitis in children >2?
Neisseria and S. pneumo
what bacteria cause meningitis in immunocompromised?
Staph spp., G- enteric bacilli, Pseudomonas
how should meningitis be empirically treated? what do they cover?
- dexamethasone 2. 3rd gen ceph for strep, Neisseria, H. flu 3. vanc for resistant strep and G-‘s 4. penicillin for Neisseria 5. ampicillin for listeria 6. doxycycline to cover RMSF and Lyme 7. acyclovir to cover herpes encephalitis
what type of meningitis is splenic dysfunction a risk factor for?
Strep. pneumo
what is choline binding protein?
virulence factor for S. pneumo, important for crossing BBB in meningitis
how is meningococcal meningitis diagnosed? how is it cultured
rapid latex agglutination test on CSF
on chocolate agar
how does Neisseria escape the immune system?
phase variation: turn off capsule on invasion of mucosal cells, turn back on in bloodstream
what causes the fever and rash of meningococcemia?
endotoxin: LPS
how can individuals exposed to Neisseria be prophylactically treated?
1 pill of ciprofloxacin
rifampin
how is H. flu cultured?
chocolate agar
why does type B H. flu cause meningitis?
has antiphagocytic polyribotol capsule
what is used to treat H. flu meningitis? what is it commonly resistant to?
3rd gen cephalosporin
ampicillin resistant
why is a gram stain of CSF not very useful in ruling out bacterial meningitis?
Listeria doesn’t gram stain well, intracellular
diarrhea/abdominal discomfort may precede meningitis caused by what bacteria?
listeria
what is the treatment of listeria?
ampicillin
which cryptococcus species causes meningitis primarily in HIV and which accounts for most of fungal meningitis in healthy individuals?
HIV: neoformans
healthy: gatii
what type of fungus is cryptococcus?
encapsulated yeast
what is the disease progression of fungal infection to meningitis?
initially asymptomatic pulmonary infection
chronic infection leads to meningitis
how can cryptococcus be diagnosed in lab?
yeast with halos on India ink
how is cryptococcus meningitis treated?
amphotericin B and flucytosine
how is meningitis due to Exserohilum rostratum treated?
IV voriconazole for 3 months
what characteristically causes necrosis of temporal lobe? what CSF finding indicates necrosis? how can it be visualized? how is it treated?
HSV-1 encephalitis, RBC’s in CSF, not usually seen on CT, acyclovir
which flaviviridae cause encephalitis? what is the genoma?
+ssRNA
West Nile, St. Louis, and Japanese encephalitis
what is the most common cause of arboviral pediatric encephalitis in US? how does it present? what type of virus is it?
La Crosse virus
seizures and focal neurological signs
bunyavirus
what is the genome of bunyaviridae? how is it different from influenza?
segmented -ssRNA
replication in cytoplasm, mRNA’s not spliced
what is the genome of rabies virus?
enveloped, non-segmented -ssRNA
bullet-shaped
exaggerated gag reflex is a sign of what disease?
rabies
what virus uses ambisense replication?
Lymphocytic Choriomeningitis Virus (LCMV)->arenavirus
how is LCMV spread?
aerosolized from rodent excreta/saliva
how does a brain abscess show up on CT? how is it treated?
ring-enhancing lesion with surrounding edema
3rd gen cephalosporin and metronidazole to cover Bacteroides fragilis
what is the primary cause of spinal epidural abscess? what is the major sign and key feature?
S. aureus (90%)
point tenderness, esp. to touch
key feature: worse pain on lying down
how does RMSF cause encephalitis?
attacks vascular endothelium: systemic vasculitis attacks brain parenchyma causing confusion, seizures, focal deficits
how is RMSF treated? Lyme disease?
doxycycline for both, ceftriaxone for Lyme disease
what are two presentations of neurosyphilis? how is it treated?
general paresis, tabes dorsalis (dorsal column demyelination)
high dose IV penicillin
how does TB affect the brain? where is most severe? what is a common complication?
chronic granulomatous meningitis, esp. severe at base of brain; thickened basal meninges cause entrapment of CN’s
