Antimicrobial Efficacy Test

Antimicrobial Effectiveness Testing (AET), also known as Preservative Efficacy Testing, evaluates whether a product's preservative system can successfully prevent microbial growth during manufacturing, storage, and consumer use. It requires inoculating a sample with standardized microbes (bacteria, yeasts, and molds) and tracking the population over 28 days.

Why It’s Done

Consumer Safety: Ensures multidose aqueous and non-sterile products (e.g., cosmetics, topical medications, and injectables) don't become contaminated and cause infections.

Compliance: Required by regulatory agencies (like the FDA) for multidose and sterile products to guarantee that the formulation remains robust throughout its shelf life.

How the Testing Works

The standard guideline followed is USP <51> in the United States, along with equivalent international methods like EP (Europe) and JP (Japan).

Inoculation: The product is intentionally contaminated with known quantities of standardized microorganisms (typically Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Candida albicans, and Aspergillus brasiliensis).

Monitoring: Samples are tested at specific time intervals (e.g., Days 7, 14, and 28) to count the number of surviving microorganisms.

Log Reduction: Results are calculated as \(\log _{10}\) reductions to verify the preservative's lethality or ability to stop microbial proliferation.

Standard Guidelines & Methods

Different product categories are subject to distinct requirements:

USP <51> (United States Pharmacopeia): The gold standard for compendial testing of drugs, botanicals, and cosmetics.

ISO 11930: Commonly used in the personal care and cosmetics industry to evaluate the antimicrobial protection of a cosmetic product.

Microbial Limits Testing: Often conducted alongside AET as a precursor to method suitability, confirming that the product itself does not harbor natural contaminants.

from Google AI overview of "antimicrobial efficacy test"

Antimicrobial Efficacy Test

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