The sterility assurance predicament:  There is no practical way of verifying the sterility of individual objects that have been through a sterilizer. 

Therefore, it is imperative that the three critical steps in testing the efficacy of the sterilizer process is followed which include:  Physical monitoring, the use of external and internal CI (chemical indicators) and the frequent use of BI’s (biological indicators).

Physical Monitoring:  Includes the recording of the sterilizer’s temperature, time and pressure on digital printouts, recorders, displays and/or gauges.  This provides real-time assessment of the sterilization cycle and a permanent record in the form of a chart or printed readout.  Physical monitoring helps to detect malfunctions sooner allowing you to take corrective actions.

Chemical Indicators:  Chemical Indicators are a critical part of an effective quality assurance program and should be used in conjunction with physical monitoring and biological indicator testing.  Best practices recommend that external and internal CI’s should be used for all items being sterilized.  Chemical indicators range from Class 1,2,3,4 and 5 as briefly described below: (See Sterilization Supplies for our full line of chemical indicators).

•      Class 1 chemical indicator:  A process indicator often referred to as an external indicator.  They distinguish between processed or unprocessed items and indicate that they were exposed the sterilizer.  These are seen as indicators on pouches, sterilizer tapes or labels.

•      Class 2 chemical indicator:  Is designed for a specific test procedure (e.g. The Bowie-Dick test used to determine if air removal has been adequate in dynamic-air-removal sterilizers)

•      Class 3 chemical indicator:  Is a single parameter indicator.  It is designed to react to one of the critical parameters of sterilization.

•      Class 4 chemical indicator:  Is a multi-parameter indicator.  It is designed to react to two or more of the critical parameters of sterilization.

•      Class 5 chemical indicator:  Is an integrating indicator.  This chemical indicator reacts to all three parameters of sterilization which include proper amount of time, temperature and pressure of the sterilizer.  They have been correlated to the performance of a biological indicator when used according to the manufacturers conditions noted on the label.

Biological Indicators:  (Also known as spore tests or BI’s) are paper filter strips inoculated with millions of spores.  They provide the only way the sterility process can be measured.  Sterilizer manufacturers validate their sterilizers by using biological indicators, and therefore BI’s should be used to check the sterilizer’s effectiveness frequently and on a routine basis. The CDC, The Joint Commission, AAMI and others are now recommending DAILY monitoring of sterilizers using biological indicators (or at least each day the sterilizer is being used). 

It is also recommended that a PCD be used when testing a sterilizer.  A “PCD” is a process challenge device.  This device is to be equal or greater than the most difficult item that is routinely sterilized such as a large pack or tray.  Often the device is assembled ‘in-house’ using towels folded and stacked with a BI (biological indicator) or CI (chemical indicator) in the center of the stacked towels.  A PCD should be representative of a package or tray that routinely is processed through the sterilizer.  PCD’s are also sold commercially (see Sterilization Supplies that are FDA cleared, although there is no universally accepted PCD for table top sterilizers.  PCD’s that are commercially available present a challenge to your sterilizer using a BI or CI in the center of the pack, but it may not represent your own particular tray or pack, which is why we recommend that the user sets up their own PCD “device” as noted above.  For more technical information, contact us at info@autoclavesporetesting.com.

PROOF OF STERILIZATION CONCLUSION:  If your facility is following the guidelines as noted above and as recommended by The CDC, The Joint Commission, and AAMI, and you have documented Third-Party Laboratory results of biological and chemical indicator test results, this will ensure you, your staff and your clients that your sterilizer is functioning correctly and is in fact sterilizing.