Terragene® Bionova® BT20 Biological Indicator

The Terragene® Bionova® BT20 Biological Indicator is a single-use self-contained biological indicator (SCBI) for routine monitoring of steam sterilization process efficacy. It contains Geobacillus stearothermophilus spores on a paper carrier and a glass ampoule with purple pH-indicator culture medium that turns yellow if live spores survive sterilization. Results are read after 24-hour incubation at 60°C.

The subject device is nearly identical to the predicate BT220 SCBI in construction (polypropylene tube, filter paper spore carrier, glass ampoule with pH indicator), organism type and spore population (≥10⁶ Geobacillus stearothermophilus ATCC 7953), resistance parameters (D-values at 121°C, 132°C, 135°C), incubation temperature (60±2°C), and shelf-life (2 years). The key difference is a reduced incubation readout time: 24 hours for BT20 versus 48 hours for BT220. The predicate also includes a fluorescence-based readout option via MUG substrate; BT20 relies on visual pH color change only.

ISO 11138-1:2017, ISO 11138-3:2017, ISO 11138-8:2021, ISO 11140-1:2014, and FDA Guidance for Industry on Biological Indicator [510(k)] Submissions (October 2007) and Chemical Indicators (December 2003).

The devices share identical intended use (steam sterilization monitoring across the same temperature and time cycles), same organism strain and spore burden, equivalent resistance characteristics and incubation conditions, and identical shelf-life. The chemical process indicator on the label is identical in ink, location, and visual interpretation. The only substantive difference—reduced incubation time from 48 to 24 hours—is supported by performance testing demonstrating ≥97% sensitivity across all partial sterilization cycles. Since the fundamental performance (same spores, same resistance, same recovery medium) is unchanged and the faster readout is validated to perform as well, the subject device does not raise new safety or effectiveness concerns.