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Meeting Sterility Testing Requirements

Meeting USP/EP/CFR sterility testing requirements with two media

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+44 (0)141 946 9999

Tel +44 (0)141 946 9999


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Sterility Testing

Sterility testing of cell lines, media, in-process material, and final products must be performed during the manufacture of pharmaceuticals and medical devices. We offer regulatory-compliant Membrane Filtration Sterility and Direct Inoculation Sterility for:

  • Cell & Virus Bank – MCB, WCB, CAL, EOPC
  • Final Bulk
  • Final Vials
  • Research Cell Banks or Cells at Limit
  • Unprocessed Bulk Harvest

All of our sterility testing is conducted in Grade A isolators or ISO Class 5 sterility suites that are continually subjected to an environmental monitoring program.

Direct inoculation (immersion)

Sterility testing of unprocessed and final bulk, final vials, prebanking cells, and cell and virus banks is typically performed by directly inoculating the test article into 2 different types of media that support the growth of aerobic and anaerobic bacteria, respectively. Test articles are incubated for 14 days followed by testing for microbial contaminants. Note - Fungi are also detected.


  • Small volume required
  • Replicate samples can be tested
  • Preferred method for materials that cannot be easily filtered

Membrane Filtration

To address issues such as large volumes of test article and the potential presence of inhibitors of microbial growth on samples, we employ membrane filtration to test for enable sterility testing. In this method, bulk articles or effluent from vials of final product are passed through a membrane filter designed to retain microbial contaminants.

The filters are rinsed to remove inhibitors and then incubated in two types of media and assayed exactly as in the direct inoculation method described above.


  • Enables testing of large sample volumes
  • Preferred method for products that can be filtered
  • Can remove inhibitory substances by rinsing the filter membrane with a suitable agent

Direct Transfer

Medical devices, solid dose forms, ointments, and creams may be directly immersed in growth media to test for bacteriostatic and fungistatic activity. Microbial detection is performed in a similar manner to direct inoculation after 14-day incubation. We offer custom protocols to accommodate parts of devices and solids, and will work with you to determine the best method with which to test your articles.

For test articles produced by non-aseptic manufacturing processes, a bioburden (or microbial limits) detection assay should be performed. Furthermore, it is often necessary to evaluate a non-sterile test article according to U.S. FDA and EP recommendations and guidelines for “objectionable organisms.” A microbial limit approach is recommended for the evaluation for objectionable organisms.

Contact an expert about your sterility testing needs.

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