Sterilisation 3 Flashcards
What is bioburdence estimation
How to estimate the starting population of the organism
what is the importance of bioburdance estimation
Initial population numbers required in order to specify sterilization parameters & inactivation kinetics.
definition of bioburdence. how is it found out
A population of viable microorganisms on or in a product and / or package’- remember organisms on the package are included
Bioburdance is a multistep process
transfer to lab on site or at other company.
treated to remove the cells from the material without killing them
direct techniques to get bioburdence?
contact with culture medium
this is the most ideal
cut a piece then put directly onto culture medium (agar plate)
but this isn’t always possible
explain indirect techniques to get bioburdence?
contact with eluent or
physical treatment
transfer to culture medium
in indirect techniques, why might a eluent be needed? what must we be careful of?
wash the microbes off
that its not killing the cells
why might detergents be used as an fluent sometimes?
to break bonds between MOs and the surface of the product. Must make sure there’s no weak antibacterial activity.
in indirect techniques, when would physical treatments be used? examples
if stuck more strongly. This can be in the presence of an eluent. Eg/ shake flask for 10 seconds. Mechanical shakers to be consistent. Or ultrasound to make the cells vibrate. Must be careful about frequency you use and for how long- can kill the cells if not careful.
small beads in mixture and shake- must be correct size
TF: there’s a universal growth medium. meaning?
false
some good general purpose media but never one that can allow any bacteria to grow as different bacteria have different nutritional needs
Conditions assessed during validation of a technique
example of a general purpose agar
Tryptone soya agar
what does sabaroud dextrose agar allow to grow?
yeast and fungi not bacteria
when selecting a growth media we want the _____ CFUs and _____ variety of colonies
highest
greatest
are there national standards for bioburdance?
no national standards, own in house standards are made. Level that they think is acceptable and as long as the product is below that level.
3 steps of process operation
cycle development
Cycle validation- providing proof that the process works- this is KEY
Cycle monitoring- once you’ve got all the evidence, you need to monitor the process to ensure you get the desired end result
what needs to be documented about process validation?
evidence that provides a high degree of assurance that a specific process will consistently produce a product meeting its’ pre-determined specifications
process validation steps?
installation qualification
performance qualification:
- physical qualification
- microbiological qualification
what is installation qualification?
is the equipment used to get the results working properly
what comes under performance qualification?
des it do the job we want it to?:
physical qualification is the best method- test the eg/ autoclave and measure conditions eg temperature profiles. Its accurate and consistent.
Microbiological- tends to be used as a backup to support physical Q OR If physical isn’t available
example of biological indicators for microbial qualification
spore strips- most resistant. put on the product and sterilised to see if there’s any survivors. if you can sterilise the most resistant, it should work on the others
point of using biological indicators
to provide a means of assessing directly the microbial lethality of a sterilisation process
what is needed to test EtO sterilisation. why?
Used for validation and monitoring (EtO) sterilisation- used only for EtO as no way to test this one
biological indicators are characterised by?
- Strain of test organism
- Reference to culture collection
- Manufacturers name
- Number (10^6) CFUs per test piece
- D value
- Z value
- Recommended storage conditions
- Expiry date
- Disposal instructions
factors governing choice of biological indicators?
- Stability
- Resistance
- Non- pathogenic
- Recovery- of any surviving spores- to provide proof that the process hasn’t worked
recommended test biological indicators for filtration techniques?
Brevundimonas diminuta
recommended test biological indicators for moist heat techniques?
Bacillus stearothermophilus
recommended test biological indicators for dry heat techniques?
Bacillus subtilus
recommended test biological indicators for irradiation techniques?
Bacillus pumilus
recommended test biological indicators for EtO techniques?
Bacillus subtilus
what is preferred over aseptic processing?
sterilisation of product in the final container
what sterilisation technique do we ideally want to use
heat
