<prompt> sterilization accuracy is assessed by using ?clostridium perfringensgeobacillus stereothermophilusclostridium butyricumbacillus subtilis  <response>: TYPES OF BIOLOGICAL INDICATORS : BIOLOGICAL INDICATORS contain the bacterial spores used for monitoring. The spores used are Geobacillus stearothermophilus for testing steam or chemical vapor sterilization or Bacillus subtilis for testing dry-heat or ethylene oxide gas sterilization. Currently, no BIs are available for routine testing of liquid chemical sterilants or disinfectants. Demonstrating the death of bacterial spores provides the main guarantee of sterilization, because it assess the process directly using live resistant microorganisms. Using bacterial spores to monitor the sterilization process is referred to as biologic monitoring or spore-testing and the bacterial spores used for monitoring the sterilization process are referred to as biologic indicators BIs. REF : ANANTHANARYANA 9TH ED 