Bioburden is the presence of microorganisms on a surface (or complete item), inside a device, or from a portion of liquid, prior to sterilization. Bioburden can be introduced from the raw materials used in the manufacturing process, via the workforce or manufacturing environment. With numerous sources of potential contamination, the bioburden of a product can fluctuate between batches. Bioburden testing is a quality control process used during production to quantify microbial contamination in water, raw materials, or finished products to ensure the safety of a manufactured product. Effective quality control and accurate test results are essential to minimize risks for consumers and required by regulated production environments. Hence, bioburden analysis is often included in routine testing performed by manufacturers to ensure the safety, quality and regulatory compliance of each product batch.

Why Test For Bioburden?

A knowledge of bioburden can be used in a number of situations as a part of ;
• Validation and re-validation of sterilization processes
• Routine monitoring for control of manufacturing processes
• Monitoring of raw materials, components or packaging
• Assessment of the efficiency of cleaning processes
• An overall environmental monitoring programs

Bioburden Protocol

ISO 11737-1 specifies the requirement and provides guidance for the enumeration and microbial characterization of the population of viable microorganism on medical devices.

It also describes detailed procedure in conducting bioburden test on medical devices from selection of product samples and appropriate method for bioburden determination to microbial characterization of bioburden.

In addition, the validation of the bioburden method emphasizing on the extraction efficiency (correction factor determination) either by repetitive extraction or inoculation procedures can also be found in this document.

The procedure for bioburden test using the membrane filtration method is as follows:

Extraction solvent is sterilized in a suitable size bottle and autoclaved just before use.
• The sample is immersed aseptically into the solvent once cooled.
• Extraction is carried out using ultra-sonication
• The extract is then passed through a membrane filter to collect any microorganism removed
• The membrane filter is then placed onto an agar plate and incubated.
• Aerobic & anaerobic bacteria and also yeast & molds colonies are counted and recorded
• The total number of colonies in the test sample is calculated as the total cfu observed
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Bioburden and Related Tests.

MB102a - Determination of bioburden by membrane filtration (aerobic bacteria + yeast & molds) - 3 parameters
• MB102b - Total aerobic and anaerobic bioburden by membrane filtration method - 5 parameters
• MB102c - Total anaerobic bioburden by membrane filtration method
• MB102d - Determination of bioburden of liquid samples by pour plate method (aerobic bacteria + yeast & mold) - 3 parameters
• MB102e - Total aerobic and anaerobic bioburden by pour plate method
• M102f - Correction Factor determination for bioburden - repetitive extraction
• MB102g - Correction Factor determination for bioburden - inoculation method