Disease Niches (how niche connects to symptoms) Flashcards
How diseases are connected to the infected niche with the human (23 cards)
What is the niche of S.aureus
Nasopharynx
Why is it stable in this niche
Can evade the I.S. and our antibodies
- sequesters IgG Fc chains by binding them
- Creates coats of polymers to surround it and camouflage
What 4 diseases can it cause
- Furuncles (pus pockets, self-contained)
- Endocarditis (heart valves)
- Indwelling devices (catheters, pace makers)
- TSS (cytokine storm and shock)
Where do we get S.A. from?
Our own body when we get a wound
1/3 of us are colonised
Colonisation can come and go (transient) but also may persist across a person’s lifetime
4 reasons why S.A. is good at colonising and damaging us
- Range of VFs for colonising range of areas
- Evades the I.S.
- Can move into deep tissue
- Lives for long time on surfaces (E.g. catheters)
What is the niche of S.pneumoniae
Nasopharynx
Why is it not stable in this niche
Cannot evade the I.S. well, so only stays for 3 weeks max
Causes disease only when immune system compromised
What 4 diseases can it cause?
- Meningitis
- Otis Media
- Pneumonia
- Sepsis
How can pathogens in the nasopharynx easily move?
The nasopharynx links many parts of the body
- Easily cross to brain through a hole
- Very vascular to move to blood
- On the passage to airways
Why does S.P. cause 2 types of disease
Invasive
Non-invasive
Depending if they reach major organs/blood or not major ones E.g. bronchitis, otis media
What niche does C.difficile inhabit?
G.I tract
Why does C.difficile only cause in disease G.I tract?
Different survival strategies from different diseases -> stays in niche as it is tailored to that
Why do S.aureus and S.pneumoniae cause so many diseases
- Highly adaptable
- Able to discern different environments and make VFs accordingly
- Many VFs to change environment and cause different disease based on that environment
What are the symptoms of endocarditis (upon infection of the heart by S. aureus)
- High temperature
- Tiredness
- Weight loss
- Petechiae
Clumps of bacteria can act similar to blood clots.
LETHAL - Organ failure or stroke
How can Staphylococcus aureus cause septicaemia?
Abscesses of S. aureus shed, releasing bacteria into the blood stream -> causing immune response across body leading to lethal drop in blood pressure
What type of infection is septicaemia?
A metastatic infection (wherein the pathogenic agent is able to spread to multiple sites across the body)
What cells make up the nasopharynx:
- Mostly squamous epithelial cells and ciliated coulmnar cells (beat the cilia to move mucous)
- Beneath the epithelial layer there are many macrophages seromucous glands (produce mucous) within the submucosa
What formation within the nasopharynx is used for nutrient acquisition S. pneumoniae?
The mucous is used as a carbon and nitrogen source.
40-50% of its genome is dedicated to the metabolism of sugars.
How does S. pneumonia cause Meningitis?
-> S. pneumoniae gains access to the meninges after breaching compromised epithelial tissue (coinfection) and crossing short distance of soft tissue -> reaches top of the brainstem
How does S. pneumonia cause Oditis media?
S. pneumoniae gains access to the ear via station tube openings/ valves in the nasopharynx
How does S. pneumonia cause Pneumonia?
S. pneumoniae gains access to lungs, as droplets are carried across inhaled air into the lungs
How does S. pneumonia cause Sepsis?
S. pneumona gains access to capiliaries via either a lung infection or across epithelial tissue within the nasopharynx.
What is S. pneumoniae’s main obstacle to establishing infection?
S. pneumoniae does not have a stable niche, instead inly surviving due to its high transmission.
