Sterility test is required for biopharmaceutical products during the sterilization validation. This test is used to assess whether contaminating microorganism may be found in the sample examined under the conditions of the test. Sterility test is an official test to determine suitability for biopharmaceuticals. According to the United States Pharmacopeia, sterility test is applied to substances, preparations, or articles are required to be sterile.
Sterility test should be carried out under aseptic conditions. In order to achieve such conditions, the test environment must be adapted to the requirements of performing test for sterility. The working conditions should be monitored regularly according to appropriate samples and controls.
Suitability test is a qualifying assay that should be performed before sterility test. Generally, suitability test is used to confirm each ready-prepared media lot and each media batch used for sterility test should support the growth of fewer than 100 viable microorganisms. In addition, a portion of each lot of media must be incubated and assessed for sterility according to the incubation conditions established by the method.
Two general methods for sterility test:
- Membrane filtration
- Direct inoculation.
Membrane Filtration Sterility Test
Membrane filtration sterility test is particularly appropriate for samples containing preservative, bacteriostatic or fungistatic compounds that inhibit microbial growth of potential contaminants. Microorganisms are collected by the 0.45 μm pore size filter with membrane filtration. Using the proper rinse solution, all inhibiting compounds are rinsed and the membrane filters are transferred to appropriate media based upon their ability to support the growth of anaerobic and aerobic microorganisms. The incubation time required for final test results is 14 day.
Direct Inoculation Sterility Test
Direct inoculation sterility test is the method of choice for certain products that are not filterable or deformable. In this method, the test products are added directly into the suitable media and the volume of the products should be below 10% of the total media volume. There are two advantages of the direct inoculation method:
1. providing a method of sterility test for materials which may not be filtered easily
2. consuming smaller volumes of products during test
With advanced experimental conditions and experienced technical staff, Creative Proteomics can provide effective service for sterility test depending on various methods.
[1] The United States Pharmacopeia, 30th Revision, The United States Pharmacopeial Convention: 2008.
[2] http://www.contractpharma.com/issues/2008-03/view_features/pharmaceutical-sterility-testing
