Stopper processor validation

Hi All,

I am currently validating the use of spiked stoppers for use in a stopper washer autoclave and am having a little trouble with it.

What appeared to be working was using depyrogenated paperclips through which to thread the stoppers together. The load was 10,000 stoppers + the spiked ones, sterilisation phase of 20 mins. No washing or drying was performed in order to focus solely on the sterilisation phase. (Micro dept aren’t happy with the theory that depyrogenating paperclips to hold the stoppers together eliminates growth later on post processing)

I then moved on to a different autoclave using a load of 35000 stoppers and some spiked stoppers. I have just taken a look in the incubator here and one seems to have grown. I don’t know for sure if it is geobacillus at this stage but i’d imagine it is.

Question is, has anyone else any experience with spiked stoppers that works consistently? are there any theories on why using depyrogenated paperclips worked?

Please advise!


hmmm. we spike the stoppers directly. You could just buy ready to use pre sterilized stoppers.


we are buying sterile spiked stoppers from SGM. The issue is the use of them. How do you join them together or identify them within the load?


Put them in a secondary bag…No I meant buy pre-sterilized, ready to use stoppers. Just pour them in you bowl and go. They are fully validated and accepted by the FDA.

Hi Meyert

My spiked stoppers are ready to use but to be able to find them again within a load of up to 35000 other stoppers i need a way of identifying them. This is where bunching them together with the paperclip came in.

In what application were you able to use autoclave pouches? i’m not sure they would withstand the turbulence in the stopper drum we have here. i may have a go at that though! have ever used anything else to keep them together?

Secondly, do you know of any theory as to why the use of depyrogenated paperclips causes no growth post incubation? this is the main sticking point with the micro department on site here.




Is that a Fedagari washer/autoclave that you are using? I had never seen a combination like that until recently. We wash separately, then sterilize. We have your typical pass through autoclave from Getinge, so the bags don’t tear apart. Is it possible to stop the cycle after the wash and then put the spiked stoppers in? How about some sort of mesh bag? or thread.

I don’t see why a depyrogenated paper clip would have any effect on the outcome. Unless, it causes an falsely elevate Fo because of its thermal properties. Did one run use a paperclip and other not? Also those are two different load sizes and a lot more thermal load than the first trial. I can see where you may not have attained temperature and therefore the spores would grow. What are you basing your time off, chamber? Drain? Load TCs? Just curious.

When I said ready to use stoppers…I meant in production…There is no reason to do the validation that you are doing. The stoppers come pre-sterilized and ready to use in your filling process.


Hi Tim

we do use a fedegari stopper washer. it has a rotating drum inside into which the stopper loads are placed for processing. the usual production cycle has a washing phase at the start, sterilisation then drying. for the validation cycle i’m only focusing on the sterilisation part and have created a new program which consists of a shortened sterilisation phase. i get what you mean about using pre-sterilised stoppers now but that wouldn’t be possible here.

all my trial cycles used paperclips with which to bind the stoppers into bunches so if the F0 was falsely elevated it would apply to both depyrogenated paperclips and not. perhaps it is time to try another method of keeping them together!!

i used valprobes in one of my trial cycles to see if i was reaching the temps correctly. the temps are fine. (our autoclaves are reval’ed annually also and don’t show issues really). ordinarily we’d use valprobes in the drum and drain. accpetance criteria is based HTM 2010.




Sorry for the long post…interesting to me :slight_smile:

I researched a little further, and some of our facilities do use the paper clip approach. They have no issues, but they just use it to identify the spiked stoppers, not keep them together. Others use the plastic price tag holders you find on clothing. I don’t know how else to describe. :o These little plastic tags identify spiked stoppers and allow them to move about the chamber.

Maybe it was just a false positive on the bio-indicator. Sounds like everything met acceptance criteria. Was it only one trial that failed?

The whole micro department thread…would I be safe to assume that your controls had the paper clip? and they wouldn’t grow? Is that their issue?

I’m just getting into this stopper processing as I was in IT hell for 3 years. I’m interested in why a Ready to Use stopper wouldn’t work for your application? Then I can give that feedback to our development group. Also, how dry do you actually get your stoppers after autoclaving.


hi tim

It’s great to have a long post! I’ve put this query up a couple of times with no joy.

can you find out for me how they treat the paperclips prior to using them please? i read a forum on the internet from the PDA which mentioned in one post that stainless steel wire was used by some people which i guess is fairly equivalent to using a paperclip. i also tried putting thermocouple wire through the stoppers on one occasion which was fine also. i used depyrogenated scissors to poke the holes through for them though. i wanted to stick with the paperclips out of ease of use more than anything.
can i also ask you are the stoppers that you are sterilising wet or dry??

wrt the micro dept thread, the issue is that depyrogenating something is not sterilising and there doesn’t seem to be a reason why the paperclips would be causing failures or passes. also, i had 4 failed cycles using sanitised (IPA + flame) paperclips and another 4 clean cycles with depyrogenated ones. that was until the other day with the bigger load. i did however put more stoppers than usual on the paperclips so the failure may just have been down to using too many all lodged together. (steam penetration issues possibly).

ready to use stoppers wouldn’t work here from a QA and regulatory point of view. stoppers have been processed as part of the overall manaufacturing process for years so it’s not going to change that drastically now. stopper processing works for us here - the validation approach i am working on is the new bit. this is changing over from using ampoules to spiked stoppers.

with respect to dryness, that is a whole different topic of itself!! i have done quite a bit of work around this area also due to a process upgrade in the facility in which i work. stopper dryness is dependent on a lot of factors - the stopper material characteristics, length of sterilisation (this part makes them the wettest apparently), length of dryness, method of drying etc etc. there’s a number of good articles i found recently. i have them on the computer if you want me to send them to you??


and also, the controls did not have a paperclip attached. each stopper was taken off the paperclip prior to incubation