Micro-organisms and the chain of infection Flashcards
what does HCAI stand for
healthcare associated infection
what are the common sites of HCAIs
- respiratory infections
- urinary tract infections
- surgical site infections
what are the main classifications of microorganisms that cause infection
- fungi
- viruses
- bacteria
- protozoa
what is colonisation
Colonisation presence of bacteria on a body surface without causing disease in the person
what are signs or symptoms of infection rather than colonisation
Heat, swelling, redness, pain, loss of function, pus, fever, increased heart rate, high white blood cell count
what is infection
when pathogens / disease causing microorganisms gain access to host tissue and elicit an immune response
what are commensals
Microbes that live in close association with their host & in the correct environment do not harm it and can positively benefit it e.g skin flora
what are pathogens
Microorganisms that is able to cause disease
what is pathogenicity
The ability to cause disease in a host organism
what is pathogenesis
The process of how a microorganism produces disease
what is virulence
The degree of pathogenicity e.g. genetic, structural or biochemical features
what is required of a microbe to established infection in a host
▪ Gain access to host
▪ Adhere to, enter and move to a
favourable site within host tissues
▪ Penetrate or evade host defences in
order to multiply
▪ Dissemination of new pathogens within
or outside of the host
what is each stage of the chain of infection
- infectious agents
- reservoirs
- portals of exit
- modes of transmission
- portals of entry
- susceptible host
what are infectious agents
micro-organisms capable of causing disease or illness
what are reservoirs
place in which infectious agents live, grow and reproduce
what are portals of exit
ways in which infectious agent leaves the reservoir
what are modes of transmission
ways in which the infectious agent is spread from reservoirs to susceptible hosts
what are portals of entry
ways in which infectious agent enters the susceptible host
what are susceptible host
individuals may have trails that affect their susceptibility and severity of disease
what makes microorganisms good pathogens
- small
- flagella for movement
- multiple group together
- spores - enhance ability to survive in
unfavourable conditions - fimbria - enhanced adhesion to surfaces
what are viruses
Much smaller than bacteria but still very effective pathogens. Structurally different depending upon the type of virus
examples of fungi
- yeast e.g candida albicans
- dermatophytes - ringworm
examples of parasites
- protozoa
- parasitic worms
anti-fungal medications and where they act
- Cell membrane synthesis
- Form pores in cell membrane
anti-viral medications and how they act
- Blocks synthesis of RNA/DNA
- Blocks cell entry/penetration
- Interferes with enzymes used to make
RNA
