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22 Cards in this Set
- Front
- Back
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What pH do bacteria prefer
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Bacteria prefer neutral pH - can be killed at low pH like stomach acid
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Aerobes, microaerophiles and facultative anaerobes have two enzymes that detoxify oxygen - what are they?
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SOD (super oxide dismutase) and catalase
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Classification of organisms according to their O2 requirement
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-Obligate aerobes - require oxygen
-Facultative anaerobes - grow best with O2 but can survive without -Microaerophiles - likes low O2 concentration -Aerotolerant - grow without O2 but are not killed by it -Obligate anaerobes - cant grow in presense of O2 |
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Microaerophiles are gram _
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Negative
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Capnophiles
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Organism that will grow with enriched carbon dioxide
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Catabolism vs anabolism
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Catabolism - degradation to generate energy and reducing power
Anabolism - building - biosynthesis, polymerization and assembly |
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Chemotrophic metabolism
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-Energy from chemicals - all pathogens degrade organic compounds to produce energy in form of ATP
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Fastidious organisms
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-Require numerous supplements and can be cultured on only special media such as blood or chocolate agar
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Requirements for growth of bacteria
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CHOMPKINS
C - Carbon H - Hydrogen O- oxygen M - magnesium P - phosphorus K - potassium I- iron N - nitrogen S- sulfur |
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Lag phase
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Time when bacteria are adjusting to new environment, some synthesis occurs
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Log phase
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-Time when bacteria grow fastest
-Exponential growth -Also most sensitive to antibiotics during this phase |
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Stationary phase
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Number of growing cells = number of dead cells
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Decline phase
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Period when cells start to decrease in number
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Normal flora
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Bacteria that normally inhibit the body - nonpathogenic, some produce vitamin K (enterobacteria) - may be resident or transient
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Infection
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Presence of organisms in the body, may or may not have clinical symptoms
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Disease
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Clinical manifestation of infection
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Pathogenesis
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Organism's capacity to cause infection
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Virulence
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Degree of pathogenecity
Number of severe cases/ total number of cases |
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Virulence factor
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-Affects whether organism will cause infection and how severe it will be
-Can be attachment, survival, escaping immune system |
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Infectivity
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How frequently agent is transmitted to susceptible person
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Incidence
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-# of new cases within specified time
-# of cases/# of susceptible people |
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Prevalence
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Total # of cases in population at given time
-cross sectional |
