FDA Permits Marketing of Quicker Method for Checking Effectiveness of Device Steam Sterilization

The Food and Drug Administration (FDA) announces it is allowing marketing of the Verify Cronos Self Contained Biological Indicator (SCBI), a new test that can help speed the determination of whether steam sterilization of reusable medical devices is effective.

The first biological indicator test that gives results in two hours, the SCBI is used in reprocessing, a multistep process to clean and disinfect or sterilize reusable medical devices. Properly reprocessed reusable medical devices can be used safely for more than one patient.

This is a novel and innovative use of recombinant DNA technology in biological indicator tests, says Christy Foreman, director of the Office of Device Evaluation in FDAs Center for Devices and Radiological Health. By providing faster confirmation of sterilization, this innovation may help healthcare facilities provide their medical staff with a faster turnaround of their sterilized reusable devices.

Steam sterilization is one method for sterilizing reusable medical devices, such as surgical instruments and endoscopes. It involves loading medical devices into a chamber that is sealed and filled with steam. Specific conditions such as temperature, exposure time and chamber pressure must be maintained throughout to kill microorganisms that may be present on the reusable medical devices.

Like other biological indicator tests, the Verify Cronos SCBI consists of a vial containing dried spores from the heat-resistant bacteria Geobacillus stearothermophilus. Prior to the start of a sterilization cycle, the reprocessing technician places the vial inside the sterilization chamber along with the sterilization load.

After the sterilization cycle is complete, the spores are incubated in recovery medium, a liquid that provides an ideal environment for the growth of any surviving bacteria, and monitored for spore growth. Growth of bacteria indicates that a sterilization load failed.

The Verify Cronos SCBI test uses a genetically-engineered strain Geobacillus stearothermophilusthat produces an enzyme that fluoresces in reaction with the recovery medium if test microorganisms are present after the sterilization process.

Genetically engineered Geobacillus stearothermophilus that survive a sterilization cycle will start growing and producing the enzyme within two hours, giving medical device reprocessing technicians results much faster than the 24 hours normally needed with a natural bacterial strain.

The FDA reviewed the data for Verify Cronos SCBI through the de novo classification premarket review pathway, a regulatory pathway for low- to moderate-risk medical devices that are not substantially equivalent to an already legally marketed device.

To support the de novo petition the manufacturer conducted a number of tests to assure the performance of the Verify Cronos SCBI. This included subjecting over 300 Verify Cronos SCBI to a partial sterilization cycle and then comparing results after two hours and at seven days of incubation in the growth media. Results showed that samples that fluoresced at two hours also showed positive growth at seven days.

Verify Cronos is manufactured by Steris Corporation of Mentor, Ohio.

Source: FDA