Bioburden

What is bioburden?

Bioburden is the population of viable microorganisms on a product and/or package.

What is the purpose of bioburden testing?

To determine the total number of viable microorganisms in or on a medical device, container or component after completion of all in-process steps before sterilization.
To act as an early warning system for possible production problems which could lead to inadequate sterilization or possible product recall.
To calculate the necessary dose for effective radiation sterilization and to monitor product to ensure adequate dosing.

What is the standard reference for bioburden?

ASTM/ANSI/ISO 11737 part 1: Estimation of population of microorganism in/on medical product.

What is the frequency and duration of the bioburden test?

The bioburden test is once a week. Each test requires 2-5 days incubation for the bacteria and 2-7 days incubation for the fungus.

How is bioburden maintained at a minimum level?

Monitor bioburden for raw corn starch. As a preventive action, only corn starch with a low bioburden is purchased, and properly stored.
Monitor bioburden for post water leaching tank.
Monitor environmental microbial in the packaging and testing areas.
Prevent cross contamination by good employee practice such as proper hand washing techniques.
Monitor employee health conditions, eg. stop workers who are ill or have open lesions from working.
Provide special clothing, and a separate area to don and store these garments.

An example of the importance of Bioburden

An example which stresses the need to exercise GMP controls over conditions related to microbial growth is demonstrated in a recent recall of examination gloves by a manufacturer. It was the glove manufacturer’s practice to reduce the temperature of the glove drying oven when serious mechanical problems occurred. As a result, after experiencing such a problem and then restarting the operation, a lot of insufficiently dried gloves containing cornstarch lubricant were packaged in a moist state.

After distribution of the product, a hospital called the FDA and complained that they had noted a visible black film on the surface of the lot of gloves, and that their analysis revealed cultures of Aspergillus and Fusarium. Fortunately for the manufacturer, they had lot numbers on the product which were traceable to the date the moisture had occurred and thus were able to restrict the recall to specific lots of examination gloves.