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14 Cards in this Set
- Front
- Back
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Define colonization
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microbe has taken up residence in body
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Define infection
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colonization of body by microbe that can cause disease
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Define disease
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symptoms that occur when pathogenic microbe infects body
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Define infectivity
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measure of how good a microbe is at infecting those it encounters
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Define pathogenicity
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ability of a microbe to cause symptoms
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Define virulence
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ability of a microbe to cause severe disease
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What is the measure of infectivity in amimals called? What does it mean?
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Infectious Dose 50 (ID50). It means the # of microbes needed to infect 50% of the animals exposed to them (low number = more infectious)
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What is the measure of virulance in animals called? What does it mean?
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Lethal Dose 50 (LD50). It means the # of microbes required to kill 50% of the animals exposed to them (low number = more lethal)
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What is the measure of infectivity in humans called? What does it mean?
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Attack rate of infection. % of susceptible people in the population who develop a particular disease
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What is the measure of virulance in humans called? What does it mean?
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Case fatality rate. % of people with particular disease who die (high number = more lethal)
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What are Koch's postulates?
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1. Organism present in all people with the disease
2. Organisms isolated as a pure culture 3. Isolated organism produces same diseases in experimentally infected host 4. Same organism isolated from experimentally inoculated host |
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What are Koch's postulates for?
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Prove that a microbe is the cause of disease
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Mention a microbe that is an exception to Koch's postulates
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Syphilis (Treponema pallidum). It has never been cultivated and does not cause human type illness in animals (except for rabbit testicles), however, proved to be the pathogenic microbe due to fluorescent antibody test in blood
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What are common ways of categorizing microorganisms?
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Phenotypes:
-Shape (Rod [Bacillus], Short Rod, Coccus, Coccobacillus, Spiral…) -Gram stain -Metabolism (Aerobic, Anaerobic, Fastidious…) Genotypes |
