Biological indicator vials are easy to use and interpret with a visual color readout provided within 48 hours.

Self-contained Biological Indicators (BI) for 121 °C (250 °F) gravity, 132 °C (270 °F) vacuum-assisted steam cycles. It consist of a Bacillus stearothermophilus spore strip, sealed glass ampule with growth medium, a bromocresol purple pH indicator system, brown color-coded cap with holes for sterilant penetration, and a hydrophobic filter as a bacterial barrier. A chemical indicator on the label that changes from rose to brown when processed. After sterilization, the vial is 'crushed' to join the growth media with the processed spore strip. The BI is incubated for 48 hours for visual change readout. A color change to yellow indicates surviving spores and a positive result.

Self-contained biological indicators significantly reduce the possibility of contamination, minimizing false positives, and assuring more accurate results. Indicators can eliminate recalls when used in every load. Test packs present a challenge to the sterilization process, as do the AAMI recommended test packs.