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Microbiology Testing

Cosmetic & Personal Care Laboratory Services

USP <51>, Antimicrobial Effectiveness

    The antimicrobial efficacy test evaluates the effectiveness of preservatives used in the health, beauty, personal care, cosmetic and pharmaceutical products according to USP <51>.

    Each of the known strains of pathogenic organisms (Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Candida albicans, and Aspergillus brasiliensis) with predetermined colonies population are added to the product separately. Test sample colonies are counted at specified time intervals to determine the effectiveness of the preservative. The log reduction of the microorganism at day 7, 14, 21, and 28 are reported. This test requires 28 days of preservative efficacy. The test demonstrates the efficacy of the product to stop the growth of pathogenic organisms. At least 100-150 mL or grams of the product are necessary to run this test. The antimicrobial effectiveness test is required only once per product unless the product formula or the manufacturing process involved any modification.


Criteria for Tested Microorganisms in Preservative Effectiveness

Injections, parenterals including emulsions, otic products and sterile nasal products.

Bacteria:

Not less than 1.0 log reduction from the initial calculated count at 7 days, not less than 3.0 log reduction from the initial count at 14 days, and no increase from the 14 days count at 28 days.

Yeast and Molds:

No increase from the initial calculated count at 7, 14, and 28 days.

Topically used products, nonsterile nasal products and emulsions.

Bacteria:

Not less than 2.0 log reduction from the initial count at 14 days, and no increase from the 14 days count at 28 days.

Yeast and Molds:

No increase from the initial calculated count at 14 and 28 days.

Oral products other than antacids.

Bacteria:

Not less than 1.0 log reduction from the initial count at 14 days, and no increase from the 14 days count at 28 days.

Yeast and Molds:

No increase from the initial calculated count at 14 and 28 days.

Antacids.

Bacteria, Yeast,
and Molds:

No increase from the initial calculated count at 14 and 28 days.

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