Sterility Testing

Sterility can be defined as the freedom from the presence of viable microorganisms. However, the conditions that guarantee absolute sterility are usually too harsh for active ingredients, and the definition of sterility for a medicinal product must be defined in functional terms. In pharmaceutical practice, a container is defined as sterile when the probability is less than one out of one million that it is contaminated with replicating microorganisms. Because it is not possible to open and test each container of a biological medicinal product, several samples, representative of the lot being tested and taken at different times during the filling operation, must be used to monitor sterility. This implies that when only a few non-sterile containers exist in a very large set of homogeneous containers the probability of detecting a non-sterile container is relatively low. For this reason, sterility testing uses methods with broad sensitivity, normally incubation of samples in growth media promoting growth across a wide range of microorganisms where replication can be detected visually. Sterility also relies on procedural measures that effectively prevent contamination of biological materials, such as clean room technology and other Good Manufacturing Practices. Sterility test, performed to detect microbial contaminants, is a requirement for all injectable drugs that cannot be terminally sterilized. Most biological products, including all vaccines, cannot be terminally sterilized. These vaccines are manufactured aseptically and require tested for sterility at various stages of manufacture.

Our services

Alfa Chemistry mainly offers two sterility testing methods, direct inoculation and membrane filtration, to assess the contamination of vaccine products.

• Direct inoculation

Direct inoculation is a sterility testing procedure that assesses the safety of pharmaceuticals (e.g., vaccines) and other products. In this method, the sample article is directly inoculated into two types of media. One medium allows the growth of anaerobes while the other medium supports the growth of aerobes. Then the aerobic and anaerobic microorganisms are detected separately in both media at the end of the incubation period. Generally, inoculated media are incubated for 14 days, and intermittent observations are taken in order to confirm the growth of microorganisms.

• Membrane filtration

For membrane filtration, the test material is passed through a size exclusion membrane capable of retaining microorganisms. In this method, two samples of equal volume are separately filtered through sterilized membrane filters. The 0.45 µm size pores in the membrane filter restrict the filtering of microorganisms present in the sample. Then the membranes are incubated in two types of media in order to detect aerobic microorganisms including fungi and anaerobic microorganisms. After a 14 days incubation period, the media are observed and analyzed for the growth of microorganisms. It is necessary to observe samples intermittently; at the end of the incubation period, the final observation can be taken to detect the evidence of contamination.

Why choose us

The ability to detect the presence of microorganisms and other contaminants is an important safeguard for vaccine production. By utilizing our well-equipped laboratories and experienced experts to work with your team, Alfa Chemistry provides you with sterility testing services. If you have any questions related to sterility testing, please feel free to contact us. Alfa Chemistry is always your project partner.

Our products and services are for research use only and cannot be used for any clinical purposes.

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