bioburden estimation

Question 1

what is a bioburden?

Answer 1

a population of viable microorganisms on or in a product or packaging

Question 2

what is the process of measuring bioburden

Answer 2

1. Sample selection  choosing samples statistically
2. Collection of items for test
3. Transfer to test lab variability depending where the lab is, may need to be transported long distances, so how do you prepare them for them for this?
4. Treatment (if required) to remove the cells. What techniques will you use to remove microorganisms from the product, some of which will have complex designs
5. Transfer to culture medium
6. Incubation

Question 3

what is the direct approach?

Answer 3

Direct contact between product and culture medium (agar plates). For some products this is easier than others.

Question 4

what is the indirect techniquie?

Answer 4

means you may have to wash the product to wash off any microorganism as bacteria like to stick to surfaces – usually full of nutrients.
sometimes very weak detergents are used, they wont kill cells but will remove them from the surfae

Question 5

what are the considerations needs to select the removal technique?

Answer 5

• Ability to remove microbial contamination
• Effect of removal method on microbial viability  don’t want to cause change to numbers and get a false representation
• Types and location of microorganisms
• Nature of product
• Culture conditions

Question 6

what do the types of microorganisms likely to be encountered dependent upon?

Answer 6

• Nature of product  natural are more likely to have a bioburden population
• Method od manufacture  have we added any microorganisms to the product how we made it
• Potential sources of contamination (operator, packaging)

Question 7

what is the process operation?

Answer 7

1. Cycle development is the heat killing the microorganisms you want to remove in test tube studies then moving to lab based
2. Cycle validation  proving that your experiment works. Key to the entire process.
3. Cycle monitoring  when you have all the evidence monitor every time to make sure you get the deserved end result

Question 8

what is process validation?

Answer 8

the establishment of documentary evidence that provides a high degree of assurance that a specific process will consistently produce a product meeting its pre-determined specifications. This applies to all sterilisation techniques

Question 9

what is installation qualification?

Answer 9

when you build sterilisation unit is everything you want to use working properly

Question 10

what is performance qualification?

Answer 10

does it work and do the job we want it to do properly. You can assess this in two different ways. The better of the two is physical qualification it is not subject to change (taking a physical measurement i.e. temperature profile). Microbiological is used as a back up to support physical qualification, this is when we use microorganisms which have a high resistance to the sterilisation process – but they are more prone to error and variability.

Question 11

what are biological indicators?

Answer 11

an inoculated carrier contained within its primary pack ready for use and providing a defined resistance to the specified sterilisation process. Usually they are simple things like spores’ strips, as endospores are the most resistant to remove, so you stick a stick in and you will be able to kill the most resistant form.

Question 12

wwhy do we use biological indicators/

Answer 12

• Standardised preparations containing selected microorganisms having known stable high resistance to sterilising agents – can collect D vales for endospores
• Used for validation (steam, dry heat, radiation, EtO) and monitoring (EtO) of sterilisation process
• In use, proportion of test organisms surviving the process are measure and related to the expected lethality of the process

Question 13

what are biological indicators characterised by?

Answer 13

• Strain of test organisms
• Reference to culture collection
• Manufacturers name, details of who produced
• Number (usually 106) CFU’s per test piece
• D-value
• Z-value
• Recommended storage conditions
• Expiry date – can last to 50-100 years
• Disposal instructions – how to get rid if you need to remove of them

Question 14

what factors govern the choice of BI?

Answer 14

• Stability
• Resistance (high in comparison to natural bioburden)
• Non-pathogenic – think of the people manufacturing the product
• Recoverability – you want to be able to check 100% where killed and if some don’t die you want to be able to recover the surviving spores to dispose of them properly

Question 15

what is the general guidance for the selection of sterilisation method?

Answer 15

• Balancing the advantages of available methods against their disadvantages. Is the product sensitive to heat? Is the product flammable?
• No requirements to specify which method should be used. No set guidelines you need to be able to produce validation as why the method you have chosen works
• Choice of method made at the design and development stage – this is where manufacturers will have to chose. The default is always heat sterilisation

Question 16

what is the specific guidance for selection of sterilisation method?

Answer 16

• Terminal sterilisation of product in final container is preffered to aseptic processing
• Agent in contact with all parts of product
• Process variables are controlled and monitored
• Process does not present hazards to operators or environment
• Process does not leave toxic residues within the product