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15 Cards in this Set
- Front
- Back
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Non-lactose fermenters on MacConkey agar
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salmonella, shigella, yersenia, campylobacter
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Do E coli ferment lactose?
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Yes
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Most common cause aseptic meningitis
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enterovirus
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How do + strand RNA viruses replicate?
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+ strand RNA = mRNA, can be immediately translated. First translate proteins for the viral replicase, which is an RNA-dependent RNA polymerase to make + into -, then to +. + strands can be used to make proteins, amplify infection, or be template for more - strand
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How do enteroviruses infect the CNS?
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ingest fecal material -> virus infects mucosal + lymphoid cells in pharynx/intestine (1* viremia)-> start excreting in feces, seeds to extraneural cells -> either cross BBB in WBC, or via retrograde axonal transmission
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Salk created which vaccine?
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IPV (killed virus, get IgM/IgG, no reversion, but poor mucosal immunity)
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Herpes virus structure? Where do they replicate?
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Icosahedral capsid, surrounded by envelope, linear ds DNA. Replicate in nucleus
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How are herpes viruses spread?
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need close contact, like between mucosal surfaces, b/c they are fragile and don't survive well outside of body
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Three classes of herpes viruses and examples
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Classified by biologic/molecular methods. Alpha = HSV-1,2, VZV (grow rapidly, lyse infected cells, latent in sensory ganglia). Beta - CMV (slow growth, lysis slow, latent in WBC). Gamma - EBV (replicate in lymphoid, some lytic. Latent in B cells)
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Replication cycle for herpes
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glycoproteins on envelope tether to cell surface receptors -> fuse -> capsid/virus to cytoplasm -> to nucelus -> vmRNA made by host (IE,E,L). Capsid assembles in nucleus, get envelope from nucleus,
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Criteria for viral latency
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can detect viral DNA but no infectious viruses
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Genes expressed during latency
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no viral antigens or capsids, but some low-level transcription of other genes
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VZV pathogenesis
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spread by droplet nuclei or direct contact w/ lesions -> infect lymphoid tissue in pharynx -> viremia infects multiple organs and skin -> proceeds up local sesnory nerves to establish latency in ganglia
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Pathogenesis of herpes zoster
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latent VZV present, periodically reactivates, usually quelled by T cells. Immunity decr w/ age, so virus can travel back down nerve -> illness. This boosts immunity again so only get 1 case/lifetime
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Which streptococci are resistant to penicillins
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enterococci
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