Flashcards in PA20014 applied microbiology Deck (82)
Who discovered that growth of microbes was NOT through spontaneous generation, in 1860?
Who devised a series of tests to assess germ theory of disease and mortality after surgery?
Which two scientists were the drivers of how microbiology was to be done?
Louis Pasteur, Robert koch
What's the problem with multi-dose containers?
They are used several times for different patients, should use single dose instead or use multi dose that have been sterilised by terminal autoclaving (sterilising the final container)
What was the sterilisation of topical and oral preparations triggered from?
Thyroid tablets found to be contaminated with bacteria.
Definition of sterile?
Free from all viable forms of life
It is expressed as a probability
What does the 'negative state is hard to proove' mean?
It's harder to prove that there are no forms of life, it's a lot easier to prove that there ARE forms of life present!
With the definition of sterile being free from all forms of life, one hitch is that we may not pick up all forms, how come?
When we do quality control, there is only a LIMITED AMOUNT OF MEDIA we can use to test for bacteria and this may not be sensitive to all forms of life,
Also some bacteria are impossible to grow and develop tests for as we don't understand the conditions they require.
This is why we can't say things are absolutely sterile; impossible to tell if we actually killed all forms of life.
What does ' the sterilisation process is not an all or nothing phenomenon' imply?
Sterilisation will process like a first order chemical reaction, ie the population exposed to the sterilisation process will decrease in number EXPONENTIALLY, but the number will NEVER REACH ZERO.
This basically means you never kill all the bacteria all at once, and some will always survive.
Why don't antimicrobial products state "this is 100% effective!"?
Number of bacteria left after sterilisation never reaches zero. You can't prove that all bacteria have been killed off as you can't detect some bacteria. They just kill most of the bacteria eg 99%.
What goes on the y axis of a fraction surviving curve? What does this mean?
This is a percentage, N= number of bacteria still surviving, No= number of bacteria you originally started with.
It is the fraction of surviving bacteria/ microorganisms
What does bioburden mean?
The number of bacteria present in the product before sterilisation
If you want a better level of PNSU, should you sterilise for a longer or shorter time?
Gets the probability of bacteria being present per unit right down.
What are the problems with long sterilisation times?
Drugs may start to degrade (due to high temps used)
The process is time consuming and expensive
What is the minimum required standard value of PNSU for most pharmaceutical products?
1 in 10^6
What type of bacteria can form spores?
Only SOME types of GRAM POSITIVE bacteria
What types of microorganisms are most likely to be contaminants ?
Bacteria and Fungi
What types of bacteria can be resistant to sterilisation?
Some types of gram positive bacteria that can form spores.
In what area of manufacture therapeutics are bacteria and fungi used in?
Recombinant DNA technology
What are the most stable/ resistant type of microorganism?
What are the least resistant type of microorganism?
Multicellular organisms, then vegetative bacteria and fungi
The killing of _____ can be used to validate various sterilisation methods?
Bacterial endospores. This is because they're very resistant to things like chemicals and heat therefore if you can kill the spores in your process then you can be sure other organisms are killed too.
What are prions?
Infectious agents composed of protein in a misfolded form.
Are all bacteria pathogenic?
No, most bacteria and non- pathogenic in fact!
But there are some pathogenic bacteria..
Which type of bacteria have a THICK peptidoglycan layer?
How many membranes do gram positive bacteria have?
ONE cytoplasmic membrane
What type of acids does the peptidoglycan layer in gram positive bacteria contain?
Lipoteichoic (longer ones) and teichoic acids
Which type of bacteria has a thin peptidoglycan layer? What is the intermembrane space called that this is present in?
Gram negative bacteria
How many membranes do gram negative bacteria have?
2, and outer membrane which contains PORINS and LPS, and and cytoplasmic membrane.