40 Biosafety Manual sterilized reaches 121°C and 15 PSI pressure. The tighter the autoclave is packed, the longer it will take to reach 121°C in the center of the load. • Contact - Steam saturation of the load is essential for effective decontamination. Air pockets or insufficient steam supply will prevent adequate contact. To ensure adequate steam contact, leave autoclave bags partially open during autoclaving to allow steam to penetrate the bag. Add a small amount of water inside the bag to help ensure heat transfer to the items being decontaminated (do not add water if it will cause biohazardous materials to leak out of the bag). • Containers - Use leak-proof containers for items to be autoclaved. Wherever possible, all considerations should be given to non-glass containers. Plastics such as polypropylene, polypropylene copolymer, or fluoropolymer products are capable of being autoclaved repeatedly. Place non-borosilicate glass bottles in a tray of water to help prevent heat shock. Place plastic bags inside a secondary container in the autoclave in case liquids leak out. Plastic or stainless steel containers are appropriate secondary containers. Make sure plastic bags and pans are autoclavable, to avoid having to clean up melted plastic. • Indicators -Tape indicators can only verify that the autoclave has reached normal operating temperatures for decontamination. Most chemical indicators change color after being exposed to 121°C, but cannot measure the length of time spent at 121°C. Biological indicators (Geobacillus stearothermophilus spore strips or spore suspensions) and certain chemical indicators (such as Sterigage®) verify that the autoclave reached adequate temperature for a long enough time to kill microorganisms. • Use autoclave tape on all bags of biohazardous waste. Before autoclaving bags of biohazardous waste, place an “X” with autoclave indicator tape over the biohazard symbol. Autoclave tape can also be used to indicate if media or equipment has been autoclaved. • Once a month, use a biological indicator (Geobacillus stearothermophilus spore strips or spore suspensions). Bury the indicator in the center of the load to validate adequate steam penetration. Document the biological indicator results in a log book or other suitable form. For more information about the ISU autoclave bioindicator program, contact EH&S at (515) 294-5359.
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