Validating Autoclave Cycles for Carcass Disposal in Animal Biosafety Level 2/3 Containment Laboratories

Abstract

Introduction: Animal carcasses differ in composition from other types of solid waste, and through prior testing it was determined that cycle parameters applied to general, solid biohazardous waste did not ensure proper sterilization of ferret carcasses. Objectives: The goals of this study were to develop and validate an autoclave cycle that would ensure the decontamination of infectious animal carcasses before removal from an animal biosafety level 2/3 containment suite for downstream disposal and to test different ways to prepare and package animal carcasses for autoclaving. Methods: Intact ferret carcasses were implanted with biological indicators, and the carcasses were placed in biohazard bags, then into metal pans. To test the efficacy of the autoclave cycle on larger biomasses, 1, 2, or 4 ferret carcasses were placed in a biohazard bag. A total of 4 carcasses were placed in each pan. An autoclave cycle was created to begin the study. After initial tests, minor modifications to the initial test cycle parameters were made, and a new cycle was validated for ferret carcasses up to 2 kg each. Parameters for the validated cycle were as follows: sterilization time 240 minutes, temperature 125°C, 5 prevacuum pulses, and chamber pressure 15 psi. Results: The results of this study indicate that an extended sterilization time is required to successfully decontaminate animal carcasses compared with regular, solid, and biohazardous waste. Conclusions: This study demonstrates that it is possible to sterilize multiple intact ferret carcasses per load under validated autoclave cycle conditions.

Technical and Anatomical Considerations for Reproducible Inactivation of Large Animal Carcasses by Steam Sterilization

“…Such air pockets are discussed as a cause of insufficient steam penetration and subsequent growth of BIs when ferrets with fur were sterilized inside autoclave bags. 13 Overall, using the grid and abstaining from wrapping the carcasses significantly improved heat conduction in deeper tissues, resulting in very homogeneous data sets of the pig carcass validation cycles. The more variable sterilization cycles in calves are in part addressed by the likely displacement of the reference probe when compared to the cycles of runs 2 and 3 and by the higher temperature of 134 C used in run 1.…”

“…13 The efficient inactivation of rather small animal carcasses (0.5-10.0 kg weight per individual) via steam sterilization in an autoclave chamber is widely described. [13][14][15] To our knowledge, the largest volume sterilized by this method so far comprised 6 NHPs with a maximum load of 60 kg. 15 Here we describe a method to safely inactivate large animal carcasses by using a passthrough autoclave.…”

Technical and Anatomical Considerations for Reproducible Inactivation of Large Animal Carcasses by Steam Sterilization

“…The use of efficient inactivation of infectious animal carcasses after animal studies is a crucial task to maintain the necessary biosafety conditions in terms of occupational, public, and environmental health. The current literature that deals with animal carcass sterilization is scant, and to our knowledge, studies with turkey and Cornish hen carcasses as surrogates for NHPs 14,15 and ferrets 13 exist. All animal carcasses used in these experiments had a body weight between 0.5 and 10.0 kg, which overall can be considered a small animal setup for steam sterilization.…”

“…A backup strategy for other effective inactivation methods for infectious animal carcasses must be in place. 13 The efficient inactivation of rather small animal carcasses (0.5-10.0 kg weight per individual) via steam sterilization in an autoclave chamber is widely described. [13][14][15] To our knowledge, the largest volume sterilized by this method so far comprised 6 NHPs with a maximum load of 60 kg.…”

“…13 The efficient inactivation of rather small animal carcasses (0.5-10.0 kg weight per individual) via steam sterilization in an autoclave chamber is widely described. [13][14][15] To our knowledge, the largest volume sterilized by this method so far comprised 6 NHPs with a maximum load of 60 kg. 15 Here we describe a method to safely inactivate large animal carcasses by using a pass-through autoclave.…”