Rites of Passage for Sterile Wipers


he final step in the manufacture of sterile wipers (either dry or pre-wetted) is gamma irradiation to destroy all viable organisms that may be present on the wipers or on associated packaging.  A source of confusion that often arises is how best to introduce packages of sterile wipers into the sterile suite.

 Most users understand that it’s not possible to bring a case of sterile wipers directly into the sterile suite to be unpacked there.  Even if the case were wiped down to remove viable organisms from its surface, cardboard packaging is not permitted in cleanrooms because of excessive particulation as well as being a source for mold/endotoxin contamination. Furthermore, transferring a large case from a non-sterile area into a sterile area is logistically difficult.

Under these circumstances, a more practical solution is to transfer individual bags of sterile wipers into the sterile area.  The question is:  How best to accomplish this without contaminating the wipers i.e. rendering the sterile wipers in the package non-sterile?

To develop a workable approach, follow the path of the sterile wipers.  After irradiation, the case of sterile wipers is completely free of viable organisms on the inside.  The exterior of the case will obviously be non-sterile, picking up viable organisms during the transport to your facility.  But this is of little concern, since the organisms will not penetrate into the interior of the case, and even if they could, the wiper packaging itself has been tested to ensure that no organisms can find their way inside to contaminate the wipers.   You are purchasing sterile wipers from a manufacturer that tests and guarantees package integrity, aren’t you?

Now consider the bag of sterile wipers, labelled to identify the product inside.  That bag is contained within a clear, sealed, polyethylene bag.  So, you have a bag within a bag. You are buying double bagged sterile wipers, aren’t you?  The inside of the clear polyethylene bag is sterile, and the outside, inside and contents of the sterile wiper bag itself are sterile, but the outside of the clear polyethylene bag is non-sterile since it will have been exposed to a non-sterile environment when it is removed from the case, outside the sterile suite.

The challenge then becomes how to get the double bagged sterile wipers inside the sterile suite without rendering them non-sterile.   Following is a series of steps to accomplish this:

In the non-sterile area, use polyester knit wipers, wetted (or pre-wetted) with 70% IPA.  Use one of these wipers to wipe down your gloves before handling the double bag of sterile wipers.  This will remove much surface bacteria from your gloves.  Discard the wiper used to wipe down the gloves.  Then use another clean, wetted wiper to wipe down the exterior of the clear polyethylene bag.  Do not open or pierce this bag – remember, the interior of the clear bag and its contents are still sterile.  Do not expose them to a non-sterile environment.  Introduce the wiped down bags into the pass through for the sterile suite.

Once the bags are in the sterile suite, the operator receiving the bags should follow the same wipedown procedure, substituting sterile, polyester knit wipers and sterile (i.e. filtered) 70% IPA for the wipedowns.  Again, the operator’s gloves should be wiped down, before wiping down (with a fresh wetted wipers) the exterior of the clear polyethylene bag.  Each bag received into the sterile suite should be wiped down with a fresh wetted wiper.  Only then should the clear polyethylene bags be removed.  This procedure will ensure that any contaminants on the exterior of the clear bags do not find their way onto the surface of the sterile wipe bag.

It is important to consider that even though the wipers are delivered free of all viable organisms, as soon as the package is opened the wipers are exposed to their current environment and could be compromised. Are you following a validated cleaning protocol with written SOPs?  Have you wiped your gloves each step of the passage according to your SOPs?

Another thing to think about, are you removing and disposing all opened sterile consumables – including sterile wipes – after a production lot has been completed.  This would include a situation in which only one wipe is used from the package. It’s just not worth the cost of the unused consumables to jeopardize the next production lot.  In fact, disposing of the opened sterile consumables is the best option (as opposed to trying to use them in some other non-sterile area of the facility), so that opened sterile consumables don’t inadvertently find their way back into the sterile suite and jeopardize a future lot.

Exquisite attention to detail are the rites of passage of sterile wipers into the sterile suite.

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