What is Bioburden Testing, and Why is it Important?
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Bioburden is the sum of viable microorganisms on or within a product. Bioburden tests are a large part of sterility testing. They are used to determine the microbial load on a device, which is necessary to ensure the sterilization dose is adequate.
If devices are to be sterilized by radiation (gamma or e-beam) that is required to achieve a sterility assurance level (SAL) of 10-6. Achieving this SAL means there is less than a one in a million chance a given sterilized product would contain microorganisms.
Bioburden levels can fluctuate between different batches/lots of product due to the variability of microbial exposure sources. Therefore, bioburden evaluations are generally conducted as campaigns spanning multiple lots or batches with at least 10 samples per batch.
What is the ISO 11737 Bioburden Test?
The ISO 11737 bioburden test is a procedure used to remove and quantify viable microorganisms from a product. It considers method suitability, potential microorganism types and their locations on a product, the effect of the method on microorganism viability and the nature of the product being tested. This test is required in product submissions to document the bioburden value and how well a sterilization process will work on the product. Requirements for testing are found in ISO 11737-1:2018 “Sterilization of health care products – Microbiological methods – Part 1: Determination of a population of microorganisms on products”.
Careful conduct of bioburden studies is critical to reliable, consistent results.
The method of bioburden testing is highly dependent on the material of the product. For example, if the item its completely solid we would completely immerse it into a liquid (e.g., PBS) and sonicate it, followed by membrane filtration and plating. The plates would be incubated and eventually counted to determine the bioburden.
The ISO 11737 Bioburden Test is Fast, Inexpensive, and Reliable
Bioburden tests are quick, inexpensive, and reliable means of characterizing the microbial load of a medical device or other object. To explore bioburden testing options, contact Microchem Laboratory today.
Sources:
The International Organization for Standardization. (n.d.). ISO 11737-1:2018(E) Sterilization of health care products – Microbiological methods – Part 1: Determination of a population of microorganisms on products. https://www.iso.org/obp/ui/#iso:std:iso:11737:-1:ed-3:v1:en
Millipore Sigma. (n.d.) Bioburden Testing. https://www.sigmaaldrich.com/US/en/applications/microbiological-testing/bioburden-testing
Kowalski, J.B., Mosley, G. (2011, March 29). Estimation of Average Bioburden Values for Low-Bioburden Products. Medical Device and Diagnostic Industry. https://www.mddionline.com/sterilization/estimation-of-average-bioburden-values-for-low-bioburden-products
Bailey, M. (2010, March). Notes on bioburden distribution metrics: The log-normal distribution. The Irradiation Panel. Digital Download.