The UVM autoclave testing program is in full swing. Pathology, Medicine, Nutritional Science, the Vermont Cancer Center, Dental Hygiene, Biochemistry and Microbiology all have taken on the task of testing their autoclaves and procedures with bacteria indicator vi als supplied and incubated by us at the ESF.
Some of the autoclave that were tested failed to steril ize the indicator vials on the first try. Further testing revealed that the autoclave procedures, not the autoclave itself, were at fault. Modify ing the procedures by following the suggestions below resulted in complete steriliza tion of the vials, even those that were placed in the center of a bag of biowaste (the hard est place to reach with steam sterilization).
Remember that biowaste from the autoclaves goes to a municipal landfill after we in Risk Management certify that it has been sterilized. Risk Management and the Institutional Biosafety Committee developed this autoclave testing plan to verify that sterilization of the waste is effec tive.
You are responsible for being certain that your biowaste is sterilized. Do not assume that your autoclave pro cess is doing this. If your lab uses an autoclave to ster ilize biowaste, somebody from your lab needs to check that the procedures are adequate and posted for all au toclave users to follow. Call us at the ESF (6-5400) if you have questions or need indicator vials.
Autoclave Tips
Remember that microbes need to be exposed to steam at 121 mC for complete sterilization.
Autoclave your biowaste for 100 minutes - shorter cycles usually do not allow sterilization to the waste's center. Procedures with cycles less than 100 minutes are suspect and need careful testing.
Leave autoclave bags open to allow steam to penetrate them - closed autoclave bags keep the steam away from the infectious material.
Don't overstuff waste bags - densely packed bags insulate the microbes at the bag's center.
Autoclave smaller loads frequently to minimize packing - steam moves poorly through a densely packed autoclave.
You may need to add water (250 mL) into the bag in order to increase steam contact at the bag's interior.
Any procedure is acceptable so long as the waste is sterilized! Test your procedure and autoclave fre quently using Bacillusstearothermophilus indicator vials, available through the ESF.
Indicator vials need to be placed at the center of the bag during testing to be certain sterilization proce dure is adequate. Attach a string or wire to the vial for easy removal after autoclaving.
The UVM Safety Information home page is found at: http://esf.uvm.edu