Direct Inoculation vs Membrane Filtration in Sterility Testing

Laboratories must perform sterility testing to ensure that products are contaminant free

by | Mar 12, 2023

Sterility testing is often performed on pharmaceutical articles to identify the presence or absence of contaminating organisms. The United States Pharmacopoeia (USP) and European Pharmacopoeia (EP) both require specific articles and substances to be sterile. Surfaces are considered sterile if there is less than a one out of one million chance that the surface is contaminated with a microorganism. Sterility tests are performed through direct inoculation,  or through membrane filtration testing, both are described below.syringe-1574486__340

Direct Inoculation

Direct inoculation, also known as immersion, testing the substance, surface, or article being tested is inoculated directly into a tube or bottle that has an appropriate medium already inside. The tubes are then incubated for 2 weeks. This type of sterility testing is advantageous because it can be performed on materials that cannot easily be filtered and it consumes less product during bacteriostasis and fungistasis testing.

Membrane Filtration

Membrane filtration testing first requires the article or substance to pass through a “size exclusion membrane” that can retain microorganisms. Rinse fluid is then passed through the filter and the membrane is transferred to the test medium. The membrane is then incubated for 2 weeks. This testing type is advantageous as it allows for large volumes of samples to be tested.

Contract Laboratory has received numerous requests from organizations needing laboratories to perform sterility testing such as:

  • Pharmaceuticals laboratory needed for biological finish product testing (appearance, PH-value, osmolality polymer/Aggregate of HSA, Total protein content, Sterility, Endotoxin(LAL-Test), Biological Activity, Liquid particle count. It`s 4000 IU/ml.(proforma)
  • Canada microbiology laboratory needed for pharmaceutical sterilization validation and Sterility assurance testing
  • A pharmaceutical microbiology laboratory is needed for Vitamin B12 injection testing for sterility, purity, and contaminants
  • Medical Device Manufacturer needs medical device laboratory for sterilization validation of the device sterilization process.
  • A pharmaceutical Microbiology laboratory is needed for sterility testing using membrane filtration, and mycoplasma testing (culture-based method) according to Japanese pharmacopeia
  • A Microbiology Laboratory needed for sterility testing of diagnostic reagents and then identification testing of any failures by culture identification testing
  • and many more!

If your organization is looking for a laboratory to perform your sterility testing, contact us at 1-855-377-6821, or submit a request online!

If you are a laboratory that routinely performs sterility testing, register today and gain access to all our high-value, pre-screened leads!

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