Infection 1 Flashcards
Define infection
Invasion of a hosts tissues by micro-organisms.
What are the three ways that micro-organisms cause disease after invading a host?
- multiplication
- toxins
- host response
What are some of the main ways infection be gained?
- airborne
- via a vector (e.g Mosquitos)
- from animals
- intimate contact
Define Microbiota
A collection of micro-organisms in a particular area that are normally harmless, but if they spread to another area, can cause infection/harm.
Give an example of Microbiota.
E.Coli. Has normal presence in the large bowel. If it spreads to the urinary tract, it can cause a UTI.
Briefly explain the process of Gram Staining
- Add crystal violet dye
- Add iodine- forms a complex with the crystal violet
- Add acetone
- Add red dye
Gram negative bacteria are red, Gram positive remain purple/blue.
What is the result of gram staining?
Gram negative bacteria are stained red.
Gram positive bacteria are stained blue/purple.
Give two examples of Gram negative bacteria.
E.coli
Shigella
Neissarie
Salmonella
Give two examples of Gram positive bacteria.
Staphylococci
Streptococci
Clostridium
What is horizontal transmission?
Transmission of infection via contact, inhalation of droplets, aerosols etc.
What is vertical transmission?
Transmission of infection from mother to child.
Define dissemination.
The act of spreading something.
Outline the five steps of micro-organisms causing disease.
Exposure Adherence Invasion Multiplication Dissemination
Name three disease determinants.
- inoculum size
- resistance
- host co-morbidities
- infection site
- virulence factors (exotoxins and endotoxins)
Define exotoxins
Toxin released by bacterium into surroundings
Define endotoxins
Toxin in bacterium that are released when it disintegrates.
Name some supportive investigations to confirm a diagnosis of infection. (6)
FBC LFT CRP Kidney function test Imaging History theology
Name a specific test used to confirm an infection diagnosis.
Gram staining
What does the microbial world consist of? (4)
Viruses, bacteria, fungi and parasites
What are bacteriophages?
They are viruses that infect bacteria, which can then go on to cause infection.
Describe the appearance of a coccus bacterium.
A round shape
Describe the appearance of a bacilli.
A rod shape
Describe the appearance of a staphylococcus.
Grapes
Describe the appearance of streptococcus.
A strip of cocci.
What are obligate aerobes and anaerobes respectively?
Obligate aerobes- requires the prescence of oxygen to survive.
Obligate anaerobes- require the absence of oxygen to survive.
Give an example of a yeast fungi.
Candida
Give an example of a mold fungi.
Dermatophytes- ringworm and athletes foot.
