Abstract: A heat stable culture medium is prepared by substituting glycerol for carbohydrate components such as dextrose that are prone to Maillard reactions. A preferred medium contains pancreatic digest of casein, soytone, soluble starch, a phosphate buffer system, a salt, a pH indicator, and glycerol as a primary carbon source. The culture medium is pH and color stable when exposed to steam sterilization, including post-manufacture steam sterilization when used as the medium of a self-contained biological indicator. A self-contained sterility indicator device contains a flexible cylindrical tube having an opening at one end. The tube contains a submicron screen as a gas transmissive, bacteria impermeable window, an adsorbent wick bearing at one end viable microorganisms, and a frangible glass ampule containing the culture medium. The end of the wick containing microorganisms is located away from the ampule and adjacent the screen.

Abstract: Structure for evaluating the efficacy of sterilization apparatus using either steam or ethylene oxide as sterilant is disclosed. The structure includes an insert of porous material having a cavity formed therethrough for retaining a biological or chemical indicator. The porous material has homogeneous porosity throughout. The insert of porous material and indicator are enclosed within an outer covering which is relatively impervious to penetration of gases and which provides restricted pathways to air and sterilant. The outer covering is provided with removable portions which are removed when the structure is used to evaluate ethylene oxide sterilization. Removal of the portions enlarges the existing pathways for ingress and egress of gases which may be appropriate in certain efficacy testing.