USP <71> Sterility Testing

USP <71> sterility testing for medical devices, pharmaceutical products, and radiopharmaceuticals is a required testing process for sterilization validation and lot release. USP <71> sterility testing is conducted in three primary ways for the following applications:

  • Membrane filtration, primarily used for pharmaceutical products
  • Direct transfer, primary used for medical devices
  • Product flush, used for products with hollow tube construction

Boston Analytics provides expertise in USP <71> method suitability for your products and applications. Our processes also include sterilization process validation to ensure the integrity of the test itself. Reliable, accurate testing and validation services help ensure that patient safety is not compromised and that products and processes meet regulatory requirements, including cGMP and FDA standards.

Membrane Filtration Sterility Testing

Typically used for filtrable pharmaceutical products, this method of sterility testing uses a 0.45 micron pore size filter to collect microorganisms from a sample. The filter is then transferred to an aerobic medium or an anaerobic medium, depending upon the microbes being tested for. The following media are generally used:

  • Fluid thioglycolate medium (FTM) incubated at 30 – 35 degrees Celsius. Used for anaerobic microorganisms.
  • Soy-based medium incubated at 20 – 25 degrees Celsius. Used for aerobic microorganisms, including yeasts and molds.

The medium is examined throughout the 14-day incubation period for signs of microbial growth, including turbidity and pellicle formation. Any contaminants present are then confirmed and identified by agar streaking.

As with all testing processes, BA Sciences membrane filtration testing equipment is validated to ensure accurate results. Membrane filtration is the preferred method for pharmaceutical products, particularly those that contain preservatives or other inhibitors of microbial growth.

Direct Transfer Sterility Testing

Typically used for medical devices, this method of testing involves submerging the entire product in the testing medium, allowing microorganisms to transfer from the product to the medium. This process is especially useful for scenarios where a medical product or device may not have been sufficiently sterilized, resulting in damaged but not destroyed microbes. In the direct transfer method, these microbes are able to repair themselves and can thus be accurately identified.

Direct transfer typically takes place in two types of media. BA Sciences undertakes the appropriate processes to aseptically separate the product into two or more pieces for testing in both types of media. We are also able to work with larger products, where contact areas must be identified, removed, and tested. Samples are incubated for 14 days, during which media is regularly examined for signs of microbe proliferation.

Product Flush Sterility Testing

Typically used for products with hollow tubes, this method involves flushing out the tube and filtering the eluate through a submicron membrane. The sample is then transferred to FTM and soy-based media for the 14-day incubation period, and regularly examined for microbe growth.

Test Validation

BA Sciences adheres to all guidelines for USP <71> Sterility Test qualification, including the Suitability Test – which ensures that microbes, if present, will grow in the testing medium – and the Validation Test, which ensures that the test sample does not inhibit the growth of microbes through stasis. These validation processes are essential in ensuring that your testing processes remain compliant and are supportive of your approval and release objectives.

Vaporized Hydrogen Peroxide (VHP) Ingress Testing

VHP ingress testing is performed within an isolator after VHP decontamination. VHP ingress into a test article container may affect the validity of the results. The purpose of this test is to determine if VHP ingress into a test article container occurs, in order to ensure the validity of the results obtained.

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