Principles of infection 1 Flashcards
What are the stages of infection
- Survival of microbe and spread to the host
- Adherence of microbe to the host and entry into
the host - Multiplication
- Evasion of host defences
- Damage to the host
- Shedding of microbe and spread to the
environment or to another host
What are the modes of transmission of microbes?
-Airborne/droplet
-GI tract
-Through the skin
-From inanimate objects
-Other epithelial surfaces
What is the diameter of droplets?
-Droplets are >5 microns in diameter
How do aerosols and droplets behave?
behave ballistically
What are droplets <5 microns known as and why are they more dangerous than droplets?
Droplets smaller than 5 microns are known as droplet nuclei or aerosols and remain suspended in the air for long periods and may travel relatively long distances from the person coughing/sneezing
What is R0?
R0 (“R nought”) is the mean number of people infected by one individual with the
infection).
What is the transmission route via GI tract?
-Faeco-oral route
-Food and water
-example is e.coli
What bloodstream infection can arise following intravascular line?
-Bloodstream infection with staphylococcus epidermidis following insertion of intravascular line
What is fomite and an example of it?
-A fomite is an object that may be contaminated with a microbe and then be a source of infection
-medical instruments and many other everyday objects
-Toy on children ward
When does multiplication of microbe work
-This occurs after internalisation of the microbe
What are the local symptoms of infection?
-Redness, swelling, warmth, pain, loss of function
What are the systemic symptoms of infection?
-Fever, Rigors, chills, tachycardia, tachypnoea
What is an acute infection?
-Rapid onset, brief period of symptoms and resolution within days
