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44 Cards in this Set
- Front
- Back
- 3rd side (hint)
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virulence factor
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physical attributes or components of the microbe that affect their ability to cause disease
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transmission
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the manner by which a microbe spreads
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What does the epidemiology of infection describe?
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- the population of hosts infected
- circumstances contributing to the susceptibility and infection of the infected |
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encounter
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microbe contact with POTENTIAL host
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entry
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microbe entry into the body either with or without crossing epithelial barriers
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spread
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the broadening of the range of infection from the site of entry
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multiplication
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reproduction of the microbe in the host
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dissemination
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movement of the microbe to sites peripheral from the site of entry
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incubation period
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time required for the microbe to multiply before host is defined to have the disease; few or no symptoms may be evident
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normal flora
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normal host bacteria that serves as a protective barrier against exogenous microbes
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pathogenesis
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process by which virulence factors contribute to disease in an individual host
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Koch's postulates
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- criteria that proves a specific microbe causes a disease
- used to formulate ways to interfere with transmission |
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Sporadic infection disease pattern?
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where an individual in a population develops a disease
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endemic infection disease pattern?
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disease is always present in a defined population, implying an equilibrium level between host/microbe/baseline level of infection
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epidemic disease pattern
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where the incidence of disease in a population is higher than normal
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colonization
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when a microbe enters the host and habituizes.
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herd immunity
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the barrier to epidemic; when the entire population can't be infected by the agent.
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What are Koch's postulates?
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1) agent must be found in the diseased
2) agent can be taken from diseased and grown in vitro 3) agent cultured in vitro must be able to infect susceptible animals 4) agent should be reisolated from experimentally infected animals |
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What are the four steps a pathogenic microbe must complete before it can cause a disease?
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encounter, entry, spread, multiplication
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microbes that can cross the placenta
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rubella, syphilis, toxoplasmosis
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PqRST!
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fomite
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inanimate objects that transmit infectious agents (IV, catheter, doorknobs, money)
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Most common barrier to spread of infectious agent?
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immunological
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Factors that influence spread of microbe?
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host anatomical factors and microbe physical characteristics
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inoculum size
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the amount of microbe that enters the host; affects the ability of the host to overcome barrier
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example: small doses of bacillus can't grow in penicillin but larger doses produce enough penicillinase to destroy penicillin and flourish
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What is the difference between infection and disease caused by infection?
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- disease is an impairment of host function and its corresponding symptoms dependent on host/agent interaction
- infection may not produce symptoms or impair host function |
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Some barriers to infection?
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- respiratory tract
- GI tract - immune system - skin |
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What occurs after ecounter, entry, spread, and multiplication?
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damage or disease
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What are the ways that infection can cause symptoms?
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- direct cell damage
- activation of host immune response |
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organelles
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P = none
E = yes |
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method of division
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P = binary fission
E = mitosis |
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ribosomes
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P = 70S (hint: they are smaller)
E = 80S |
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endocytosis
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P = can't, no membrane-bound organelles!
E= obvi |
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cell wall
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Present in all bacteria except mycoplasma
- fugus, algae, plant |
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What are the layers of most bacteria?
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1) surface layer
2) cell wall 3) plasma membrane 4) nucleoid 5) ribosomes 6) surface appendages |
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What virulence factors are affected by bacterial surface layers?
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- resists phagocytosis
- aids in tissue adherence |
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What are capsules/slimes and where are they produced?
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capsule = polysaccharide, slime is slime,
- produced on plasma membrane and secreted through the cell wall |
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What is the capsular antigen of S. Pneumoniae used in?
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- vaccines
- differentiation with varying Ab's |
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number of chromosomes
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P = a single circle/ haploid
E = multiple chromos/ diploid |
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bacteria without a cell wall
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mycoplasma
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cocci
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spheres
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bacilli
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rods
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spirochetes
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spirals
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forms a septum that separates daughter cells in division
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cell wall
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part of bacterium targeted for antibiotics
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enzymes used to make cell wall
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