Suggestions for the best use of biological indicators
Stop trying to put a square peg into a round hole!
Biological Indicators (BIs) have evolved quite a bit over the years. The continued development of new and improved biological indicators has continually made the practice of monitoring sterilization processes a fairly easy and inexpensive process. Even with the evolution of the biological indicator there still isn’t always a BI for every situation. As new products, medical devices, and sterilization processes are created there isn’t always a readily available BI that is adequate for monitoring these items or processes. What should you do if you have a situation where a standard BI just doesn’t quite work? HAVE ONE MADE THAT DOES!!!
A person might say, “It doesn’t matter what type of biological indicator I place in my load, it will tell me if I reach my SAL (Sterility Assurance Level). If the BI is killed that means I achieved my target SAL and as long as that happens I am happy.” That argument will work great until you have a failure. Then what should be done? Time and time again, a customer will call and say “there is something wrong with your BI”. Once all the details are presented, more often than not it is either improper use of the BI or the wrong BI all together. The reason there are so many different types of BIs out there is because not every BI is appropriate for every situation. Proper selection of BIs for your process is of the utmost importance.
Another customer might state, “I can just cut this BI into smaller pieces or fold it a few times and it will work for my application”. You might think you can reconfigure a standard BI in a way that it will work but if you do that it will most definitely affect the performance of the BI. A biological indicator is a system composed of the inoculated substrate and the primary packaging. Modifying any of the components of that system will affect the performance of the BI. The two most likely characteristics that will be affected by modifying a BI are the population and resistance. This could mean that you are providing too little or too great of a challenge as to what was originally intended and you wouldn’t be adequately monitoring your process. If the modification affected the BI in a way that it reduced the challenge you could completely inactivate the BI and your processed load could potentially be unsterile. If the modification affected the BI in a way that increased the challenge it could result in positive growth of the BI even though the sterilization cycle conditions should have been adequate to sterilize your load and completely inactivate the BI.
By Robert Bradley, M.S.
Director of Laboratory Production
Omaha Manufacturing Facility
Mesa Laboratories, Inc.
Spore News. MESA Lab. Custom Biological Indicators.
