Abstract: A sterilization indicator device comprises a receptacle for containing a spore disc and a sealed ampule of culture medium. A closure is threaded onto the receptacle and cooperates with the receptacle to provide a passageway for the sterilization gases to reach the spore disc. Upon completion of the sterilization, the closure is threaded further onto the receptacle to fracture the ampule and cause the nutrient to come into contact with the spore disc. At the same time an indicator flag is moved from an initial position to a second position to indicate that the device has been activated. Also, a seal is provided between the closure and the receptacle to seal off the spore disc from exposure to ambient air during incubation of the spore strip.