How sterility test method validation performed and what is the purpose of sterility test method validation?

In sterility testing, we test different types products like general products and antibiotics etc. Every product is having different type of nature with respect to its mode of action. In case of antimicrobial product they can kill the contamination if present in the product and we are not able to detect the contamination inside the product. We may get false negative results and fail product can be released into the market. It may become threat to patient safety.

To avoid this situation we first need to perform the sterility test method validation. In sterility test method validation, we perform the sterility of the product, positive product control (PPC) and positive control (PC). In sterility testing of product, product is reconstituted by rinsing fluid A,D or K as per product requirement and filter through 0.45 micron filter. Rinsing shall be given with the diluent. Basically 100 mL of pre-wetting and 3x100 mL final rinsing shall be given. After that cut the filter paper into two equal halves and one half shall be inoculated in SCDM media and another half shall be inoculated in FTM media. Sample shall be incubated for up to 14 days. In case of PPC, sample shall be tested as in case of product by giving 2x100 mL rinsing of fluid A,D or K depending upon the product and in last 1x100 ml of rinsing not more than 100 cfu per 0.1 mL microorganisms specified in the pharmacopoeia shall be inoculated. Membrane filter shall be cut into two equal halves and incubated in respective media as per the used microorganisms. PPC sample shall be incubated for not more than 5 days. In case of PC, product is not reconstituted and filtered. In PC, 2x100 mL rinsing of fluid A,D or K depending upon the product shall be given and in last 1x100 ml of rinsing not more than 100 cfu per 0.1 mL microorganisms specified in the pharmacopoeia shall be inoculated and filtered.  PC also incubated for not more than 5 days. No growth shall be observed in product up to 14 days of period. Comparable growth of PPC with PC shall be observed. If comparable growth observed it means either product does not contain any antimicrobial property or antimicrobial property of the product has been successfully removed. 

In sterility method validation we need to validate the number of rinsing to remove any antimicrobial property of the product so that it does not inhibit the growth of microorganisms which may be transferred into the product through the process. 

If antimicrobial property of the product can not be removed by rinsing only then neutralizing agents by proving its efficacy and toxicity or different rinsing fluid can be used.

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