Preservative Antimicrobial Effectiveness TestingPreservative Antimicrobial Effectiveness Testing Laboratories
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Preservative Antimicrobial EffectivenessPreservative Antimicrobial Effectiveness Testing

Antimicrobial Effectiveness test / Preservative Efficacy Testing / USP 51

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Antimicrobial preservatives are added in the products to protect them from microbial contamination.Since all useful antimicrobial substances are toxic, therefore, antimicrobial preservatives should not be used as a substitute for good manufacturing practices. The concentration of the preservative to be effective in the final packaged product should be below toxic level.

Where antimicrobial preservatives are added to protect the product from microbial growth, similarly antimicrobial preservatives are also added to inhibit the microbial growth that may be introduced during manufacturing, after manufacturing or from daily use of the product by consumer.

Who Orders USP 51 antimicrobial effectiveness test
  • Pharmaceutical product developer or manufacturer
  • Cosmetic Product developer or manufacturer
  • Antimicrobial Product developer or manufacturer
  • Miscellaneous other antimicrobial product developer or manufacturer

USP 51 antimicrobial effectiveness test Method

Antimicrobial efficacy test evaluates the effectiveness of an antimicrobial preservative. According to USP51 standard, five indicator organisms are Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans and Aspergillus niger. Additional microorganisms can be tested depending upon the product demand. The test is carried out in such a way that the product is challenged with 100000 to 1000000 cfu/ml of the test microorganisms. Samples are tested at different intervals (7, 14 and 28 days) to determine the surviving number of the organisms. Log reduction is calculated by using calculated concentration cfu per ml of test microorganism present at the start of the test and cfu per ml of microorganisms survived at 7, 14 and 28 days of the challenge. The test demonstrates the antimicrobial efficacy of the product to stop the growth of organisms if it complies with the USP 51 test criteria for antimicrobial effectiveness.

Turn Around Time USP 51 antimicrobial effectiveness test

The microorganism survival is monitored till 28 days.

Sample requirement USP 51 antimicrobial effectiveness test

A minimum of 100 - 150 ml or grams of the product is needed to run this test. Smaller volume samples can also be accommodated if you are short on product.

For Antimicrobial effectiveness testing call 800-282-7102 or email

Microbiological Testing Labs

Last updated 12-19-2017


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