Tests Used in Steam Sterilization

Sterility Assurance is an important factor of sterilization. Several manufacturer provides several method of testing for the efficacy of steam sterilization. All are designed to test or measure specific parameters and conditions.

1. Tape Indicator - contrary to what is being practiced by many, tape indicators does not guarantee sterility of the load. They are being used on each load and are designed only to identity which load has been sterilized and which one is not.
2. Daily Air Removal Test (DART) - as the name implies, it is being used daily, preferably on the first loading, placed inside the autoclave together with the items being sterilized, usualy wrapped items or linen. They are meant to monitor the air-replacement capacity of steam in a pre-vacuum process of sterilization. The point is, if air was removed, steam has penetrated.
3. Bowie & Dick Test Pack - this test pack simulate a heavily densed pack or wrapped item. It has indicator in a wide sheet of paper and does not only monitor the penetrability of steam, but other conditions as well, such as wet loads, super heated steams, etc. It should be used with each loading or daily as may be prescribe by infection control committee.
4. Biological Indicator - this test indicator is a vial containing culture media and a spore disc containing certain type of bacteria, usually of high resistivity to extreme pressure and temperature. It is loaded to the sterilizer together with the items to be sterilized. After the sterilization, the vial is crushed, allowing the spores to come in contact with the media and then incubated for usually 24 hours. A change in color after incubation indicates growth of bacteria, therefore a failure in sterilization.

These indicators and test packs have purposes of their own and they can be used simultaneously for more accurate results.