Infection
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- Created by: Laura Hannify
- Created on: 21-03-23 14:19
Microorganisms and Infections
Microorganism - Any organism too small to be seen by the naked eye
Pathogen-Microorganisms that cause disease
Infection- The presence of microorganisms causing damage to body tissues
Pathogen-Microorganisms that cause disease
Infection- The presence of microorganisms causing damage to body tissues
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Process of infection
Four stages:
- Colonization, Invasion, Multiplication and Spread
- Colonization, Invasion, Multiplication and Spread
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Colonization
-Infectious microorganisms exist in reservoirs, e.g infected human
-Transmitted via direct contact, or indirectly by
vectors (insects), direct exposure (faecal oral transmission through
food/water)
- Human-to-human transmission by aerosolized
microor
-Transmitted via direct contact, or indirectly by
vectors (insects), direct exposure (faecal oral transmission through
food/water)
- Human-to-human transmission by aerosolized
microor
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Invasion
- Infectious agent can invade surrounding tissues/other
sites
- Developed mechanisms to penetrate tissues & avoid
host’s nonspecific and specific defences (inflammation & immunity)
sites
- Developed mechanisms to penetrate tissues & avoid
host’s nonspecific and specific defences (inflammation & immunity)
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Multiplication
-Warm, nutrient filled host environment
- Undergo rapid multiplication – replicate within infected cells (viral pathogens); replicate in macrophages &
other cells (bacterial pathogens)
- Undergo rapid multiplication – replicate within infected cells (viral pathogens); replicate in macrophages &
other cells (bacterial pathogens)
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Spread
- Produce localized infections without spread to other regions of the body
Others highly invasive - may enter lymphatics, blood, internal organs
▪ Successful spread - relies on virulence factors –
adhesion molecules, toxins & protection against host’s i
Others highly invasive - may enter lymphatics, blood, internal organs
▪ Successful spread - relies on virulence factors –
adhesion molecules, toxins & protection against host’s i
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Clinical Infectious Disease Process
Four stages:
1. Incubation period
2. Prodromal stage
3. Invasion period
4. Convalescence
1. Incubation period
2. Prodromal stage
3. Invasion period
4. Convalescence
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1) Incubation Period
The interval between exposure to an infectious agent and the appearance of
the first symptoms
- Microorganism has entered the individual,
undergone colonization & begun
multiplying
the first symptoms
- Microorganism has entered the individual,
undergone colonization & begun
multiplying
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2) Prodromal stage
▪ Pathogen continues to multiply, and the
host begins to experience general signs
and symptoms of illness
▪ Typically a result from activation of the
immune system, such as fever, pain,
soreness, swelling, or inflammation.
host begins to experience general signs
and symptoms of illness
▪ Typically a result from activation of the
immune system, such as fever, pain,
soreness, swelling, or inflammation.
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3) Invasion period
▪ Immune & inflammatory responses being
triggered
▪ Development of symptoms specifically
related to the pathogen AND symptoms
related to protective inflammatory
response
▪ Signs & symptoms of disease are the
most obvious and severe
triggered
▪ Development of symptoms specifically
related to the pathogen AND symptoms
related to protective inflammatory
response
▪ Signs & symptoms of disease are the
most obvious and severe
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4) Convalescence Period
- immune & inflammatory systems have in general successfully Removed infectious agents
Symptoms decline
▪ However, the disease may be fatal or
may enter a latency phase –
resolution of symptoms until
reactivation at another time
Symptoms decline
▪ However, the disease may be fatal or
may enter a latency phase –
resolution of symptoms until
reactivation at another time
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Clinical Manifestation of Infectious Disease
Effects may be acute, chronic, or
secondary to immune & inflammatory
responses, or from bacterial toxins or
viral injury.
Symptoms can include:
Fatigue, malaise, weakness, loss
concentration; generalised aching &
loss appetite, Fever (Hallmark).
secondary to immune & inflammatory
responses, or from bacterial toxins or
viral injury.
Symptoms can include:
Fatigue, malaise, weakness, loss
concentration; generalised aching &
loss appetite, Fever (Hallmark).
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Fever (Pyrexia)
-Rise in body temperature above the
normal i.e oral temperature (37.2 Degrees)
The body temperature is being
regulated at a higher level than normal
▪ Nervous system feedback to
HYPOTHALAMUS regulates
temperature = body’s thermostat
normal i.e oral temperature (37.2 Degrees)
The body temperature is being
regulated at a higher level than normal
▪ Nervous system feedback to
HYPOTHALAMUS regulates
temperature = body’s thermostat
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Classes of Infectious Microorganisms
Theses include:
Bacterial infection, Viral infection, Fungal infection and Parasitic & protozoal
infection
Bacterial infection, Viral infection, Fungal infection and Parasitic & protozoal
infection
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1. Bacterial infection
Bacteria – prokaryotic (no enclosed nucleus),no
mitochondria, or membrane bound organelles
Shapes of Bacteria- spherical, rodlike and spiral
Bacterial survival & growth depends on
effectiveness of body’s defences, and on the
bacterium’s capacity to r
mitochondria, or membrane bound organelles
Shapes of Bacteria- spherical, rodlike and spiral
Bacterial survival & growth depends on
effectiveness of body’s defences, and on the
bacterium’s capacity to r
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2. Viral Infection
Virus – minute particle that is capable of replication but only within living cells
Viral life cycle: Attachment to target cell, Penetration, Uncoatining, Replication, Assembly (formation new virons) and Release
Viral life cycle: Attachment to target cell, Penetration, Uncoatining, Replication, Assembly (formation new virons) and Release
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3. Fungal infection
Fungus – simple organism that lacks the green
pigment chlorophyll
▪ Infection with a fungus is called mycosis
▪ Fungi that invade the skin, hair or nails = dermatophytes
pigment chlorophyll
▪ Infection with a fungus is called mycosis
▪ Fungi that invade the skin, hair or nails = dermatophytes
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4. Parasitic & protozoal infection
Parasite – any living thing that lives in or on another living organism
Protozoa – single celled parasitic organisms
Risk factors – weakened immunity; lack clean drinking water; contact with soil containing infected animal or human faeces; live or trave
Protozoa – single celled parasitic organisms
Risk factors – weakened immunity; lack clean drinking water; contact with soil containing infected animal or human faeces; live or trave
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Countermeasures against pathogens
-Infection control measures e.g hand washing
- Antimicrobials e.g antibiotics
-Active Immunization: Vaccines. Vaccine-induced protection does not persist as
long as infection-induced immunity – booster
injections may be necessary
- Antimicrobials e.g antibiotics
-Active Immunization: Vaccines. Vaccine-induced protection does not persist as
long as infection-induced immunity – booster
injections may be necessary
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Other cards in this set
Card 2
Front
Four stages:
- Colonization, Invasion, Multiplication and Spread
- Colonization, Invasion, Multiplication and Spread
Back
Process of infection
Card 3
Front
-Infectious microorganisms exist in reservoirs, e.g infected human
-Transmitted via direct contact, or indirectly by
vectors (insects), direct exposure (faecal oral transmission through
food/water)
- Human-to-human transmission by aerosolized
microor
-Transmitted via direct contact, or indirectly by
vectors (insects), direct exposure (faecal oral transmission through
food/water)
- Human-to-human transmission by aerosolized
microor
Back
Card 4
Front
- Infectious agent can invade surrounding tissues/other
sites
- Developed mechanisms to penetrate tissues & avoid
host’s nonspecific and specific defences (inflammation & immunity)
sites
- Developed mechanisms to penetrate tissues & avoid
host’s nonspecific and specific defences (inflammation & immunity)
Back
Card 5
Front
-Warm, nutrient filled host environment
- Undergo rapid multiplication – replicate within infected cells (viral pathogens); replicate in macrophages &
other cells (bacterial pathogens)
- Undergo rapid multiplication – replicate within infected cells (viral pathogens); replicate in macrophages &
other cells (bacterial pathogens)
Back
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