In addition to testing proper disinfection and cleaning, Microtest offers reliable testing for sterilization methods that utilize steam or ethylene oxide (EO), plus other chemicals. This testing applies to medical devices designed and labeled for reuse. It qualifies the device manufacturer’s recommended parameters for required sterilization cycles.
The question: will the device be effectively sterilized at a predetermined Sterility Assurance Level (SAL)? Manufacturers most often establish a recommended SAL of 106 — yielding 1 positive result showing unacceptable contamination in 1 million cases.
Microtest’s sterilization validation process follows recommendations of the Association for the Advancement of Medical Instrumentation (AAMI), the American National Standards Institute (ANSI), and the American Society for Testing and Materials (ASTM). Our knowledge, experience, specialized equipment and techniques, and strict adherence to protocols ensure dependable sterilization studies.
The device to be tested is first inoculated with a biological challenge organism — a spore strip or liquid spore inoculum — used as an indicator. The United States Pharmacopeia (USP) and Association for the Advancement of Medical Instrumentation (AAMI) suggest organisms with high resistance to the given sterilization process. The device is sterilized, and then tested to see if viable indicator organisms are still present. If indicator growth is observed, the sterilization cycle fails the test. Valid devices must pass three consecutive, effective sterilization cycles.
Testing uses spore strips with 106 spores per strip, or liquid suspensions containing 106 spores per milliliter. Inoculated devices are cultured under an ISO Class 5 (Class 100) laminar airflow hood, using aseptic technique, determination of recovery factors, and traditional culture/enrichment techniques to optimize indicator recovery.
- All culture media undergo USP Growth Promotion Testing (GPT) and sterility assurance to ensure optimal recovery and sterility
- Incubators are calibrated and monitored 24/7 via an advanced SCADA system
- Bacterial spore populations used in biological challenges are controlled and verified per USP prior to use, and their D-value reported
- Each sample is tested with positive and negative controls
The reporting interval varies depending on cycle requirements and number of devices; 6 to 8 weeks are routine. Microtest also offers temperature mapping of testing devices.