ISO 11135:2014, B.1.4, BI resistance x product bioburden

[akyt]

Hello guys, could you help me?

The standard ISO 11135: 2014, item B.1.4, says that the resistance of the product's bioburden must be less than the resistance of BI. I read the guide (item D.14.1.4), but I still have doubts about how I could run the tests to meet this item.

The standard talks about a fractional cycle and the sterility test after the cycle, but if there is growth in the BI and the product, how can I guarantee that the BI is still more resistant? Should the exposure time of this fractional cycle be defined to allow BI growth? Should I use product samples as if it were a routine sterilization? And how do I define the sampling?

If someone has another test suggestion to ensure that the BI is more resistant than the product's bioburden, please share. I will be very grateful for your support.

Thank you in advance.

 

[levatorsuperioris]

Characterize your bioburden (population) with fractional cycles, if your first fractional cycle kills everything in both your BI and your population, you have to restart. Its not uncommon to find your bioburden dead after your first fractional cycle, but your BI is not. This situation is normally ok, but you need to ensure the population of bioburden is => BI when you start.

If you are using Annex A you need one Fractional Cycle, if you are using Annex B you need multiple Fractional cycles to build a curve. You should likely hire a professional certified lab to design these as accuracy is critical.

You can use multiple fractional cycles per annex B in this situation you describe above.

 

[adir88]

If there is growth in both the product and BI, you need to increase the exposure until you get sterility in product. You could run some preliminary fractional cycles to work out the exposure time that gives you sterility for product but growth in your BI. Once you're happy, you can formally run it under a validation protocol to demonstrate that the product's bioburden is less than the resistance of the BI. Basically, you cannot pass your fractional cycle until you get all sterile (no growth) product.

Hope this helps.

Cheers.

 

[akyt]

Thank you so much for your contributions.
Now I could understand the fractional cycle strategy, but I have a question:
Can I use the product's natural bioburden (in its normally found population), or should I inoculate a known population (greater than or equal to the population of BI, 10^6) in a sterile product in order to compare resistance?
And having this resistance defined, how often should I redo this validation?

 

[chris1price]

No, use the natural bioburden. You are trying to show that the product is easier to sterilise than the BI. That way, when the BI is fully sterilised, you know the product will be as well.

 

[levatorsuperioris]

The point is to find out if the natural bioburden is more resistant to sterilization than your BI, innoculating would ruin the point, ie strains of species can have different resistances to Sterilization Methods -> famously troublesome was Gluteraldehyde and Mycobacterium Spores .... There are devices with extremely low CFU counts naturally, you work with what you have.

 

[adir88]

Agree with chris1price and levatorsuperioris. The point is to compare the natural resistance of the product to the BI.