Bioburden is defined as the number of bacteria living on a surface that has not been sterilized. A bioburden test determines the total number of viable microorganisms in or on a medical device. USP <1229.3>, Monitoring of Bioburden, sets up the requirement to monitor bioburden as part of your contamination-control program for sterilization processes. When setting up your process, it’s necessary to utilize a broad range of microorganisms – ones that could potentially be present in the material or medical device.
According to USP, “bioburden is a potential risk to the patient not only because the sterilization process might not be completely effective, but also post-processing because of the possible presence of residual materials such as allergens, endotoxins, and exotoxins. It may also have adverse impact on product quality and stability.”
There are two types of bioburden monitoring processes: destructive and retentive. Destructive sterilization processes include moist and dry heat sterilization, and are developed and validated to kill microorganisms. USP states “the microorganisms that are most resistant to widely used destructive processes are spores of certain Gram-positive bacteria. As a result of the resistance properties of these organisms, some species are commonly used as biological indicators for the evaluation of sterilization process performance. With the retentive process, bioburden removal capability depends on the size and quantity of the bioburden microorganisms, the pore size of the filter, the properties of the liquid being filtered, and the parameters of filtration processes.
This chapter of the USP covers:
* Monitoring and Sampling
* Bioburden Screening
* Destructive Processes
* Sterilizing Filtration
* Bioburden Control