Intro to Practical and MRSA sampling Flashcards
How does a Bunsen burner used to keep everything sterile ?
a Bunsen burner is lit to create up-draught of hot air
you need to work close to the Bunsen burner whilst its set to a roaring blue flame.
how do you streak for a single colony ?
- heat loop in flame until red hot then keep it close to the flame for 5 secs whilst it cools
- touch a colony with the sterile loop and spread the cells out over surface of agar
- the loop needs to be sterilised between each step
why are liquid cultures usually used in Erlenmeyer (conical) flasks ?
Normally important to achieve sufficient aeration.
where is staphylococcus aureus usually found ?
its often found on the skin and in the nose of healthy people, ‘carriers’
what happens if S. aureus enters the blood stream ?
it can cause more serious systemic infections:
- bacteremia
- sepsis
- septic shock
what is bacteremia ?
bacteria are present in the bloodstream
what is sepsis?
serious bodyside response to infection including raised white blood cell levels, fever, weakness, increased heart rate and rapid breathing
what is septic shock?
dangerously low blood pressure associated with sepsis, resulting in organs receiving too little blood and leading to organ failure; septic shock is life threatening
what does MRSA stand for ?
methicillin-resistant S.aureus
where does MRSA occur mist commonly ?
In hospitalised people
what does S. aureus do to mannitol salt ?
S. aureus ferments mannitol to produce acid this changes the agar from normal red to yellow
what coloured colonies and pigments does S. aureus produce ?
It produces yellow pigments and gold coloured colonies
what is the standard unit of viable count ?
cfu = colony forming unit
-cells present which are able to develop into a colony
how long does it take for E. coli to divide (1 cell to become 2) ?
30 mins
