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30 Cards in this Set
- Front
- Back
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Types of Transmissible Spongiform Encephalopathies (TSEs)
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- Scrapie
- Bovine spongiform encephalopathy (BSE) - Creutzfeldt-Jakob Disease (CJD) - Kuru - Chronic Wasting Disease (CWD) |
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Scrapie
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- oldest known TSE
- in sheep and goats - cause fur-scraping, unusual gait - vertical transfer - not transferable to humans |
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PrP^Sc
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- Scrapie Prion Protein
- smallest known infectious agent - modified form of PrPc (found on neurons) - rich in beta sheets - insoluble - PK resistant - form aggregates - encoded by prnp gene |
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Features of TSE Diseases
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- neurodegenerative, always fatal, no therapies
- highest [PrPsc] in brain - prion accumulation --> neuron death - destruction of neurons causes spongy appearance - form amyloid plaques: insoluble fibrous protein aggregates |
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TSE symptoms
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- personality changes
- depression - jerking movements - lack of coordination/unsteady gait - lose ability to move/speak - death in months-years |
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Onset of prion diseases
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- heritable (inherit mutated prnp gene)
- infectious - sporadic (mutation of prnp gene) |
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Types of transmission for prions (most to least efficient)
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- intracerbral
- intravenus - intraperitoneal - Subcutaneous - Intragastric (oral) |
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Bovine spongiform encephalopathy (Mad cow disease)
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- major problem in UK until mid 1990s
- feeding animals remains of other animals - progressive fatal nervous sys disease - takes 4-5 years or more to develop - no diagnostic test for live animals - transmitted to humans by consumption of cow brain/spinal cord |
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variant Creutzfeldt-Jakob Disease (vCJD)
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- rare fatal TSE that affects humans
- linked to consumption of BSE-infected cattle |
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(classic) CJD
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- 3 categories:
- sporadic: no known environmental source (85% of cases) - hereditary: inherited genetic mutation (15% of cases) - iatrogenic: from surgery/contaminated medical equip (1%) |
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Kuru
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- from ritual cannibalism during funerals
- higher instances in females because they ate brain areas more often - body tremors - long incubation (5-20 years) - M129V mutation grants resistance to disease |
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Chronic Wasting Disease (CWD)
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- TSE of different species of deer, elk, moose
- transmission to humans unknown - hunters cautioned about eating meat from risk areas (esp in AB, SK, midwest) |
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Alzheimer's Disease
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- most common form of dementia
- buildup of beta-amyloid (Abeta) in brain - Abeta binds to same receptor as PrPsc (PrPc is receptor); may have common downstream mech |
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Lyme Borreliosis (Lyme Disease)
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- multisystemic disorder
- commonly presents as skin lesions (bull's eye) - most common vector-borne disease in NA - can lead to arthritis, carditis, nervous system disorders |
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Borrelia burgdorferi
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- Gram neg spirochete
- periplasmic flagella: axial filaments - no LPS on membrane, but have other lipoproteins as adhesins - spread by bite of hard ticks (Ixodes) in NA - white footed mice are major reservoir |
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Ixodes life cycle
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- larva, nymph, adult
- require blood meals between stages - majority of human infections from nymphs - B. burgdorferi not transmitted vertically |
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Lyme disease transmission
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- tick inserts barbed feeding tube
- secrete local anesthetic - transmission occurs after 24h of bite - ticks suck blood over several days - compounds in tick saliva inhibit DC activation |
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B. burgdorferi genetics
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- linear chromosome
- multiple plasmids (some linear, some circular) - plasmids required for infection - limited metabolic capacity |
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Lyme disease stages
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- Early localized stage: bulls eye rash, flu like symptoms
- Early disseminated stage: multiple rashes, swelling of large joints, heart palpitations, Bell's (facial) palsy - transverse BBB paracellularly - Late disseminated stage: arthritis, 5% develop neuro problems, slower response to antibiotics - post-treatment: lingering symptoms, may be autoimmune |
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Lyme disease vaccine
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- LYMErix
- controversial, claimed to cause arthritis - now approved for dogs |
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Staphylococci
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-Gram pos, coccus, grow in bunches
- Coagulase positive - Coagulase negative |
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Coagulase positive Staph
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- clumps in blood plasma
- S. aureus |
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Coagulase negative staph
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- forms suspension in blood plasma
- s epidermidis - s saprophyticus - cause biofilm-associated infections |
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Staph epidermis
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- coag neg
- not as dangerous as S aureus - not a good skin colonizer - resistant to many antibiotics - produces polysacch capsule - forms biofilms - found on implanted medical devices |
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Staph aureus
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- coag pos
- extracellular pathogen - pyogenic infection - hallmark abscesses (mostly on skin) - abscesses don't heal on their own |
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Staph aureus colonization
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- efficient colonizer of nares and skin
- doesn't usually cause problems - 1/3 population persistently colonized, 1/3 intermittently colonized, 1/3 will never carry- found on fomites - spread by direct or indirect contact - bind host proteins using adhesins - leading cause of nosocomial infections |
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Staph aureus direct effects
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- skin lesions
- deep abscesses - systemic infections |
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Gram stain
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pos = purple
neg = pink |
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4 stages of bacteria growth
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- lag: accumulate nutrients
- log growth: exponential growth - stationary: run out of nutrients, start accumulating waste - death: waste buildup toxic |
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Antibiotic targets
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cell wall synthprotein synthDNA/RNA synthfolate synthcell membrane alteration
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