Micro-organisms and Infection
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- Created by: Orlaith Quigley
- Created on: 20-03-22 20:03
What is a micro-organism?
Any organism too small to be seen by the naked eye
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What is a pathogen?
Microorganisms that cause disease
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What is infection?
The presence of microorganisms causing damage to body tissues
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What is Symbiosis?
Benefits human & not harm the microorganism
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What is Commensalism?
Benefits microorganism & not harm the humans
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What is Pathogenicity?
Benefits microorganism & harms the human
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What is opportunism?
A benign microorganism becomes pathogenic
because of decreased human host resistance
because of decreased human host resistance
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What happens if the physical protective barriers & normal flora are compromised?
Cuts in the skin allow normally non-infectious bacteria cause local infections/invade further/infect organs
Damage to intestinal tract releases intestinal bacteria into
the blood stream sepsis/ shock/ death
Damage to intestinal tract releases intestinal bacteria into
the blood stream sepsis/ shock/ death
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Which systems maintain much of the symbiotic
relationship?
relationship?
The Immune & inflammatory
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What happens if these systems compromised?
many microorganisms will leave
their normal site & cause infection elsewhere in the body
Individuals with an immune deficiency can easily become infected - seize the
opportunity when defensive systems are weakened
their normal site & cause infection elsewhere in the body
Individuals with an immune deficiency can easily become infected - seize the
opportunity when defensive systems are weakened
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What are opportunistic microorganisms?
Individuals with an immune deficiency can easily become infected, opportunistic microorganisms seize the opportunity when defensive systems are weakened
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What are the four stages of progression from point of view of microorganism?
1. Colonization
2. Invasion
3. Multiplication
4. Spread
2. Invasion
3. Multiplication
4. Spread
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Where do infectious microorganisms exist?
In reservoirs e.g. environment (contaminated water, soil), animals or
infected humans
infected humans
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How are microorganisms transmitted?
via:
Direct contact
Indirectly by:
-vectors (insects)
- faecal oral transmission through
food/water or soil
Human-to-human transmission by:
-aerosolized microorganisms in droplets (coughing/sneezing)
-physical contact
Direct contact
Indirectly by:
-vectors (insects)
- faecal oral transmission through
food/water or soil
Human-to-human transmission by:
-aerosolized microorganisms in droplets (coughing/sneezing)
-physical contact
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What factors does successful spread rely on?
Virulence factors –
adhesion molecules, toxins & protection against host’s
inflammatory and immune system
adhesion molecules, toxins & protection against host’s
inflammatory and immune system
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What are the four stages of infection from point of view of the infected individual?
1. Incubation period
2. Prodromal stage
3. Invasion period
4. Convalescence
2. Prodromal stage
3. Invasion period
4. Convalescence
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What is the Incubation Period?
The interval between exposure to an infectious agent and the appearance of
the first symptoms
the first symptoms
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How long does the incubation period last?
May last several hours,
Days (flu 1-
2days) COVID19
(2-14days), chickenpox
13-17days)
Years (AIDS 1-10years)
Days (flu 1-
2days) COVID19
(2-14days), chickenpox
13-17days)
Years (AIDS 1-10years)
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What is the Prodromal Stage?
The appearance of initial symptoms which are often mild including feeling of
discomfort and tiredness
discomfort and tiredness
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What is the Invasion period?
The pathogen is multiplying rapidly, invading further, affecting tissues at site
of initial colonization & other areas
of initial colonization & other areas
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When are signs & symptoms of disease are the
most obvious and severe
most obvious and severe
The invasion period
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During which stage do symptoms specifically
related to the pathogen and symptoms
related to protective inflammatory
response develop?
related to the pathogen and symptoms
related to protective inflammatory
response develop?
The invasion period
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What is the Convalescence period?
Individual’s immune & inflammatory systems have in general successfully
removed infectious agent
removed infectious agent
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What is a latency phase
Resolution of symptoms until
reactivation at another time
reactivation at another time
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Periods of disease most likely to be associated with transmissibility of an
infection depends upon which factors?
infection depends upon which factors?
the disease, the pathogen, and the mechanisms
by which the disease develops and progresses
by which the disease develops and progresses
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Other cards in this set
Card 2
Front
What is a pathogen?
Back
Microorganisms that cause disease
Card 3
Front
What is infection?
Back
Card 4
Front
What is Symbiosis?
Back
Card 5
Front
What is Commensalism?
Back
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