Direct Inoculation & Membrane Filtration Methods for Sterility Testing

Sterility testing is designed to demonstrate the presence or absence of extraneous viable contaminating microorganisms in biological parenterals designed for human use.

Charles River provides sterility testing that is compliant with both USP and EP regulations. Sterility testing is conducted on bulk or final products by direct inoculation or membrane filtration methods and can be performed in an isolator or cleanroom environment. A bacteriostasis/fungistasis test is also performed to assess whether or not the test article inhibits the growth of microorganisms. The performance of bacteriostasis and fungistasis testing is necessary in order to validate the sterility result and confirm that there are no antimicrobial properties within the test article that would inhibit the detection of microbial organisms during the sterility assay.

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Direct Inoculation Sterility Testing

  • The test article is directly inoculated into two types of media to allow for the detection of both aerobic and anaerobic microorganisms.
  • After inoculation, the media is incubated for 14 days with intermittent observations as well as a final observation at the end of the testing period to detect evidence of microbial contamination.

Membrane Filtration Sterility Testing

  • Sterile, enclosed units allow for the simultaneous filtration of equal volumes of test samples through two membrane filters.
  • Samples are incubated in two types of media for 14 days, facilitating the detection of both aerobic and anaerobic microorganisms.

Product-specific method development and consultation is also available for these testing methods.