To identify the viable contamination (bacteria, fungus, spores etc.) in the product sterility testing is the essential method. As this testing is very important, it also has one limitation that it is time consuming. Once the product sterility was done, it requires 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 required 14 days. 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 bacterium is very slow growing, and it could be the source of product contamination. To recover these type of slow growing microorganisms, 14 days are enough to support the growth of these microorganisms if present in the product. Another reason is that in aseptic environment microorganisms could be in damaged or in injured form so it requires long time for the recovery of these microorganisms in media. That’s why sterility testing require 14 days of long incubation time.