Environmental Services
Autoclave Efficacy Testing Testing Procedure Introduction to the Tools: A number of tools are available to assess the performance performance of the autoclave; autoclave; these include physical, chemical and biological indicators. It is important to note that these indicators will only respond to time, temperature and moisture conditions, and not to organic load.
Physical Indicators:
Pressure and temperature recording devices. Thermocouples can be placed inside the load to determine the temperature achieved in the bag itself.
Chemical Indicators: These indicators change colour after being exposed to specific spe cific temperatures. There are two types of chemical indicators, temperature sensitive tape (autoclave tape) and integrated chemical indicator strips. For autoclave tape, the colour change will occur upon exposure to the given temperature; it is not time related. Therefore these indicators can only attest to the temperature attained and not to exposure time and hence success of sterilization. Integrated chemical indicator strips however, provide a limited validation of temperature and time, though this is not as accurate as a Biological Indicator, and so it cannot be used as a replacement.
Biological Indicators: Biological indicators ind icators are used in the efficacy eff icacy testing of the autoclave G. process to effectively sterilize the contents being treated. stearothermophilus spores are used, as they are the most resistant organism to steam autoclaving. To determine the effectiveness of the autoclave process the biological indicator must be placed in a typical test load (solid or liquid) and exposed to the typical cycle conditions. This is the standard method of validating the effectiveness of your autoclave procedures. Testing using a biological indicator must be undertaken monthly, unless otherwise authorized by RMS.
Revised by: Stephanie Thomson Date: July 29, 2013
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Environmental Services
Procedure for Efficacy Testing with Biological Indicators: 1. Read and follow the supplier’s instructions. Link to Instructions. 2. Tie a string around the BI tube and place the G. stearotheromophilus in centre of representative test load (inside a waste bag). 3. Process load in normal fashion. 4. Extract and process the BIs a. Pull the BI from the waste bag and remove the string b. Using the ampule crusher, break the glass ampule inside the plastic tube. Be careful not to break the plastic. Do this for the positive control (a tube that did not go into the autoclave) and the autoclaved BI. c. Incubate G.stearothermophilus samples as instructed by manufacturer (55-60oC for 24-48hrs). 5. Check for colour change at regular intervals during the incubation period (24, and 48 hours). If media is yellow and turbid the autoclave process has FAILED. Immediately upon noting yellow colouration, re-run all samples with new biological indicators. 6. If failure continues to be noted, either increases time of exposure or initiate repairs to the autoclave. Note the autoclave cannot be used again until validations procedure indicates that autoclave is now adequately sterilizing the material. 7. Record all results. (Positive and Negative) Records: 1. Record biological indicator information: brand, lot #, expiry date. 2. Record the date, operator, cycle time, cycle temperature of the test run. 3. Record results: colour change noted - yellow (Failure), no colour change purple (Pass) 4. Email the results to
[email protected]
Revised by: Stephanie Thomson Date: July 29, 2013
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