Sterility – Bacteria, Mold, and Fungal Test
USP <71> fourteen (14)-day membrane filtration sterility test procedure. Tests for BACTERIA, MOLD, YEAST and FUNGI with two media at two separate temperatures. Test read on days 3, 7 and 14. Interim reports available upon request.
Sterility is defined as the absence of viable microorganisms. Here at Eagle Analytical Services, we utilize only the USP methods for analyzing compounded pharmaceuticals. The membrane filtration method is used when the nature of the product permits. If the membrane filtration technique is unsuitable, direct inoculation of the culture medium must be utilized.
When choosing Eagle Analytical Services, you have two choices when it comes to the type of membrane filtration test performed on your compound. The first is the traditional membrane filtration method, as stated in USP<71>. The second method utilizes the Millipore Steritest™ System, also a USP <71> method and considered the gold standard in the major pharmaceutical industry. The difference in the two techniques is that the Steritest method is a completely closed system in which there is very little chance of obtaining a false positive result. Regardless of the above method chosen for your sterility test, the basic methodology is the same, to meet the requirements of the USP.
Eagle Analytical Services only permits degreed personnel properly trained in microbiology to perform sterility testing in our certified Class 100 biological safety cabinet, located in our certified Class 100 clean room. Sterility testing is a very exacting procedure, where asepsis of the procedure must be ensured for a correct interpretation of the results.
Membrane Filtration Sterility Testing
According to USP <71> Sterility Tests membrane filters with a nominal pore size of not greater than 0.45µm must be used. The minimum requirements for a sample to be analyzed can be found in USP<71>. The sample is filtered and rinsed with the appropriate sterile diluent. The membrane is aseptically cut into two equal parts and transferred into each of the two suitable media. The media is then incubated for not less than fourteen (14) days.
The media found to be suitable for sterility testing are Fluid Thioglycollate Medium and Soybean-Casein Digest Medium. The fluid thioglycollate medium is primarily intended for the culture of anaerobic bacteria, as well as aerobic bacteria. The soybean-casein digest medium is suitable for the culture of both fungi and aerobic bacteria. Once inoculated, the fluid thioglycollate medium is to be incubated at 32.5°c ± 2.5° and the soybean-casein digest medium is to be incubated at 22.5°c ± 2.5°.
Eagle Analytical Services examines the media on the third and seventh day after the test has begun, as well as at the conclusion of the fourteen (14) day test, for any evidence of microbial growth. At the conclusion of the fourteen (14) days, if the sample being tested renders the medium turbid so that the presence of microbial growth cannot be determined, USP <71> specifies that a portion of the medium be transferred to a fresh vessel of the same medium. The original and transfer vessels are then incubated for an additional four (4) days for analysis.