Let’s say I received a request to validate the following autoclave cycle which is going to be used for cell culture media sterilization. The accuracy of the internal temperature probe is 1.0 C.
Sterilization temperature set point: 123.0 C
Sterilization time: 30 min
Do you build in worst case validation runs:
3 cycles at lower temperature set point e.g. 121.0 C, or shorter time e.g., 20 minutes to ensure complete sterilization during routine.
3 cycles at higher temperature set point e.g. 125.0 C, or longer time e.g., 40 minutes to ensure growth media is still performing well.
-> Do you still need to add an empty chamber test for each of these conditions including the one at the requested set point (30 min at 123.0 C)? 3 cycles for each set point = 9 cycles in total.
…or can you just validate the parameters as they are defined by the requestor (then we have 3 cycles for load + 3 cycles for empty chamber)? In this case the when monitored temperature during routine sterilization phase would deviate from the set point that was validated, how much deviation is allowed, and how to defend such events?
Hi Monepok,
If you have already qualified your autoclave and you need to qualify a new load, no need to go for empty chamber (heat distribution) cycle.
If you qualify your cycle for 20 min an d if you say you would recomment 30 min as routine cycle, no one may accept as you would not know your media behaviou in 30 min cycle. Same case with 40 min cycle. Better, develop a cycle which your media can withstand and which can provide you a minimum sterility assurance (6 log)
First I would change your cycle and that sterilization time be 15 minutes. Why? Cell media is temperature labile and it is not recommended to hold it longer period at high temperature. 15 minutes sterilization time is enough!
Fo values collected during heating/cooling will give you enough safety margine and for liquid load better to use Fo values than time/temperature.
But, lets go back to your case. First I would do a run with nominal parameters - to see what lethality collect during regular sterilization. After that I would be performed 3 runs with worst case parameters and BIs.
If autoclave have controled lower temperature (let say if temperature fall below 122oC alarm is occured) then i would set 122oC as worst case. Beside that I would short time from 30 minutes to 20 minutes to calculate Fbio in the case that BIs do not have D value greater than 2.
And to resume - one mapping + 3 worst case parameters runs with BIs. That runs with longer times does not have sense because you will never have such situation and each cell batch is tested for grow promotion.