Sterility testing is the method to check viable contamination (bacteria, fungus, spores etc.) in the product. This testing is very important but it is time consuming. Once you tested the product, it require 14 days of long incubation time.As we know that bacteria require 3-5 days for the growth and fungus require 5-7 days for growth then why sterility incubation require 14 days?
Sterile products are manufactured in aseptic environment and that environment must be suitable for the sterile product manufacturing. We perform environmental monitoring to check viable contamination in the area and to control viable contamination we perform disinfection, sanitization and fogging in the area. Personnel are also involved in the aseptic manufacturing activities and in aseptic area personnel are the main source of product contamination. Sterility testing require 14 days of long incubation time because there are some bacteria which are very slow growing like Propionibacterium acne. P.acne is gram positive, rod shaped, slow growing bacteria which is found in the acne of humans. This bacteria is associated with the humans and very slow growing and it could be the source of product contamination. So, for the recovery of these type of slow growing microorganisms, 14 days are enough to support the growth of these slow growing microorganisms if present in the product. Another reason is that in aseptic environment microorganisms could be in damaged or in injured form so it require long time for the recovery of these microorganisms in media. That's why sterility testing require 14 days of long incubation time.
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ReplyDeleteI think a good follow-up question is then this.... Since the "Test of Sterility" is really just a variation of the MPN Bioburden test, why aren't bioburden tests incubated to 14 days? Even MPN bioburden tests aren't. Additionally, why is the test of sterility incubated at 28-32 C, where bioburden (including MPN bioburden) is incubated at 30-35 C?
ReplyDeleteThanks Frozen Rope for your valuable comments. Here my point is to discuss the topic in simple way which would be easy to understand for a fresher as well as for an experienced person. I know the SAL value, its importance and role in sterilization but it would be difficult to explain each and everything in single blog. Its better to explain these thing in my another blog. Once again thanks for your suggestions. Have a nice day!
ReplyDeleteBut why not 16 days or 20 days of incubation for slow growing bacteria...why only 14 days.
ReplyDeleteSterility testing require 14 days of long incubation time because there are some bacteria which are very slow growing like Propionibacterium acne. P.acne is gram positive, rod shaped, slow growing bacteria which is found in the acne of humans. This bacteria is associated with the humans and very slow growing and it could be the source of product contamination. So, for the recovery of these type of slow growing microorganisms, 14 days are enough to support the growth of these slow growing microorganisms if present in the product. Another reason is that in aseptic environment microorganisms could be in damaged or in injured form so it require long time for the recovery of these microorganisms in media. That's why sterility testing require 14 days of long incubation time.
DeleteBut why not 16 days or 20 days of incubation for slow growing bacteria...why only 14 days.
ReplyDeletethank u sir for nice information
ReplyDeletebut my second question in these metho direct inoculation method after 14 daycompletion transfer in a second container one ml sample and incubate .Why ?
ReplyDeleteDinesh sahu, some products are hazy in nature and if you perform sterility by direct inculation method sometimes you can't predict whether turbity is there in medium or haziness. In this situation where you can't predict whether your sample is pass or fail, you have to transfer the not less than 1 ml sample of doubtful sample to same medium and incubate at same temperature for not less than 4 days with the orignal container also. If there is no turbity in the sample then your sample is pass but if you found turbity then your sample is fail.
DeleteRefer USP 39 chapter 71 (Sterility Testing)
Thanks and have a nice day
Dinesh sahu, some products are hazy in nature and if you perform sterility by direct inculation method sometimes you can't predict whether turbity is there in medium or haziness. In this situation where you can't predict whether your sample is pass or fail, you have to transfer the not less than 1 ml sample of doubtful sample to same medium and incubate at same temperature for not less than 4 days with the orignal container also. If there is no turbity in the sample then your sample is pass but if you found turbity then your sample is fail.
DeleteRefer USP 39 chapter 71 (Sterility Testing)
Thanks and have a nice day
Hello sir i appriciate your site and your blog ..i have question we perform sterility test and we cheaking for 14 days some time before we have audit he said sterlity test is need only 7 days? Is it true?
ReplyDeletehello sir why use in a incubation temp of candida albicans in 30-35 degree
ReplyDeleteFor fast growth of candida albicans
DeleteWhy only 14 days incubation and not 10 days 16 days or 20 days. Please reply
ReplyDelete