What are the three domains into which life is split?
What are the main pathogens that can affect humans?
What is "virulence"?
The level of infectivity of a pathogen
A bacterial cell wall is composed of ___________
What is peptidoglycan
The main constitute of a bacterial cell wall
It is essentiall a suger caging - repeating polysaccharide stucture with peptide cross links - providing a rigid structure and barrier
Which two types of bacterial cell wall exist?
(There are also bacteria without a cell wall)
How are gram positive and negative bacteria differentiated?
By performing a gram stain
What is a gram stain?
A test used to differentiate between gram positive and negative bacteria.
Crystal violet dye is used to stain the cell wall - specificially the peptidoglycan layer
The extent to which the dye is retained determines the type of bacteria
Gram positive - thick peptidoglycan layer - stay purple
Gram negative - thin peptidoglycan layer - turns pink
Gram positive bacteria have a _____ peptidoglycan layer allowing them to deal with ______ internal pressures.
Of both gram positive and negative which of the two has a larger periplasmic space?
(They have two different periplasmic spaces)
Which bacteria class has two membranes?
(Outer and plasma)
What exists on the outside of gram negative bacteria that confer antigenic properties?
Lipid polysaccharides (endotoxins)
Besides having antigenic properties, what other important characteristic do lipid polysaccharides possess?
They have bacterial toxin properties which cause damage to neighboring cells and evoke an inflammatory response
Why are gram positive bacteria more susceptible to antibiotics?
The outside peptidoglycan layer can act as a target for antibiotics such as penicillin
What happens when antibiotics bind to the peptidoglyan layer of gam positive bacteria?
The peptide cross links within peptidoglycan are broken down
What are flagella and fimbriae (pili)?
Extracellular proteinaceous extensions
What are some of the functions of flagella and fimbriea?
- Increase bacterial surface area
- Can act as a syringe to inject proteins and RNA into cells
- Passage of DNA from one bacterium to another - horizontal gene transfer
- Motility (only flagella)
What 5 key factors so bacteria require to grow and thrive?
- Food (C, O, H, N, salts and vitamins etc.)
- Correct temperature
- Osmotic pressure
- Oxygen content
What are aerobic bacteria?
Bacteria that require oxygen to grow
What are microaerophiles?
Bacteria that only require minimal oxygen to grow
What are facultative anaerobes?
Bacteria that can use oxygen if it is available, but do not require it to function
What are obligate anaerobes?
Bacteria that do not require oxygen at all
What are the stages in the chain of infection?
- Infectious microbe
- Portal of exit
- Mode of transmission
- Portal of entry
- Susceptible host
What are the only 5 ways in which infection can be spread?
- Inoculation (vaccination or artifical introduction) - direct or indirect
- Mother to infant - vertical transmission
- Intercourse - STI or STD
In what 5 situations (clinically) is hand washing necessary?
- Before patient contact
- Before aseptic task
- After bodily fluid exposure
- After patient contact
- After contact with patient surroundings - when leaving zone
What are black bags for?
What are orange bags for?
For serious airbourne pathogens, those infected should be kept within a ________ ________ room
What is the definition of disinfection?
Any process by which the level of microorganisms is reduced to a safe level
What is the definition of sterilisation?
A process by which all microorganisms are killed or removed to render the object incapable of causing infection