The D-Value, or decimal reduction time, represents the time required to inactivate 90 % of a given microorganism under particular conditions. If less biological indicators are tested than the D-Value determination requires, the result is a reasonable estimate that can be used as a basis for quality control of a batch of biological indicators.
The quality control team of SKAN Laboratories offers a D-Value estimation based on recognized standards. Testing takes place exclusively in SKANs H2O2 decontamination facility to simulate real conditions.
- How many biological indicators are used for a D-Value Estimation?
According to the SKAN test procedure, 31 biological indicators are required to perform a valid D-Value estimation. Since this procedure is an approximation, more accurate results can be obtained if more biological indicators are used.
- Which media are used to control the inactivation state?
After successfully completing the H2O2 decontamination of the isolator system, the biological indicators are incubated in tubes containing 9 mL of Trypcase Soy Broth (TSB). Biological indicators that are not completely inactivated will cloud the carrier liquid. Statistical analysis of the tubes showing active and inactive biological indicators provides the estimate of the D-Value.