INDICATOR BIOLOGICAL STEAM 100/BX Self-contained biological indicator can be incubated for 24 hours for use in incubator (MDS200580) Distinctive color change from purple to yellow helps indicate spore survival and inadequatesterilization Steam prevacuum cycle compatible Steam Biologicals Indicators. Distinctive color change (from purple to yellow) indicates spore survival and inadequate sterilization. Self-contained biological indicator that can be incubated for 24 hours in any small incubator. Unit: BX