Understanding USP <51> Antimicrobial Effectiveness Testing: Ensuring Product Safety & Compliance

By PBR Laboratories — Defining Excellence in Laboratory Services Since 1984

What is USP <51> Testing?

USP <51>, also known as Antimicrobial Effectiveness Testing (AET), is a critical microbiological analysis used to determine the ability of a preservative system to inhibit the growth of harmful microorganisms in multi-use or long-shelf-life products.

This test is not only essential for ensuring product safety but is also a regulatory requirement for many products in pharmaceutical, cosmetic, natural health, and veterinary industries.

Why USP <51> Matters

Products that are intended for repeated use over time — such as creams, ointments, oral solutions, and lotions — are particularly vulnerable to microbial contamination. To prevent the growth of yeasts, molds, and bacteria, manufacturers use preservative systems.

However, regulatory agencies like Health Canada, the U.S. FDA, and the European Medicines Agency (EMA) require scientific evidence that these preservatives work effectively. That's where USP <51> preservative efficacy testing comes in.

How Does USP <51> Work?

The test involves inoculating the product with five standardized microbial strains:

• Staphylococcus aureus
• Pseudomonas aeruginosa
• Escherichia coli
• Candida albicans
• Aspergillus brasiliensis

The product is then observed over a 28-day period to monitor the reduction or absence of microbial growth, ensuring the preservative system is robust enough to protect consumers throughout the product's intended use.

Products That Require USP <51> Testing

PBR Laboratories provides USP <51> testing across a range of industries, including:

• Pharmaceuticals — creams, gels, oral solutions, syrups
• Cosmetics & Personal Care — moisturizers, lotions, shampoos, cleansers
• Natural Health Products — herbal extracts, tinctures, nutraceuticals
• Veterinary & Pet Products — topical treatments, oral drops
• Cannabis Topicals — infused creams, oils, sprays

Why Choose PBR Laboratories for USP <51> Testing?

With over four decades of experience in analytical microbiology and regulatory compliance, PBR Laboratories is a leader in antimicrobial testing in Canada. We understand the complexities of product matrices and the importance of accurate, timely, and compliant data.

Our USP <51> testing services include:

• ✅ Validated test methods tailored to your product
• ✅ ISO 17025 compliant laboratory practices
• ✅ Customized reporting for Health Canada and FDA submissions
• ✅ Fast turnaround times and competitive pricing
• ✅ Expert microbiologists and regulatory support

Whether you're in product development, quality assurance, or preparing a regulatory submission, our team works with you to ensure your preservative systems meet international standards.

Ready to Validate Your Preservative System?

If you're looking to meet regulatory expectations and protect your product's reputation, USP <51> testing is essential. Let PBR Laboratories help you meet these requirements with confidence.

📧 Contact us at: pbr@pbr.ca
📍 Located in Edmonton, Alberta — Serving clients across Canada and beyond
🔬 Visit us online: www.pbr.ca

Choose PBR — Because Precision Matters.
Defining Excellence in Laboratory Services Since 1984